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  • 1.
    Albertsson, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Analysis of the Many-Body Problem in One Dimension with Repulsive Delta-Function Interaction2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The repulsive delta-function interaction model in one dimension is reviewed for spinless particles and for spin-1/2 fermions. The problem of solving the differential equation related to the Schrödinger equation is reduced by the Bethe ansatz to a system of algebraic equations. The delta-function interaction is shown to have no effect on spinless fermions which therefore behave like free fermions, in agreement with Pauli's exclusion principle. The ground-state problem of spinless bosons is reduced to an inhomogeneous Fredholm equation of the second kind. In the limit of impenetrable interactions, the spinless bosons are shown to have the energy spectrum of free fermions. The model for spin-1/2 fermions is reduced by the Bethe ansatz to an eigenvalue problem of matrices of the same sizes as the irreducible representations R of the permutation group of N elements. For some R's this eigenvalue problem itself is solved by a generalized Bethe ansatz. The ground-state problem of spin-1/2 fermions is reduced to a generalized Fredholm equation.

  • 2.
    Alexandrov, Sergei
    et al.
    Univ Montpellier, UMR CNRS 5221, L2C, F-34095 Montpellier, France.;CERN, Theoret Phys Dept, Geneva, Switzerland..
    Banerjee, Sibasish
    CEA, IPhT, F-91191 Gif Sur Yvette, France.;Max Planck Inst Math, Vivatsgasse 7, D-53111 Bonn, Germany..
    Longhi, Pietro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Rigid limit for hypermultiplets and five-dimensional gauge theories2018In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, article id 156Article in journal (Refereed)
    Abstract [en]

    We study the rigid limit of a class of hypermultiplet moduli spaces appearing in Calabi-Yau compactifications of type IIB string theory, which is induced by a local limit of the Calabi-Yau. We show that the resulting hyperkahler manifold is obtained by performing a hyperkahler quotient of the Swann bundle over the moduli space, along the isometries arising in the limit. Physically, this manifold appears as the target space of the non-linear sigma model obtained by compactification of a five-dimensional gauge theory on a torus. This allows to compute dyonic and stringy instantons of the gauge theory from the known results on D-instantons in string theory. Besides, we formulate a simple condition on the existence of a non-trivial local limit in terms of intersection numbers of the Calabi-Yau, and find an explicit form for the hypermultiplet metric including corrections from all mutually non-local D-instantons, which can be of independent interest.

  • 3.
    Alonso i Fernández, Jaume
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Equivariant Cohomology and Localisation2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Equivariant localisation is based on exploiting certain symmetries of some systems, generally represented by a non-free action of a Lie group on a manifold, to reduce the dimensionality of integral calculations that commonly appear in theoretical physics. In this work we present Cartan's model of equivariant cohomology in different scenarios, such as differential manifolds, symplectic manifolds or vector bundles and we reproduce the main corresponding localisation results.

  • 4. Anderson, Lara B.
    et al.
    Constantin, Andrei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Lee, Seung-Joo
    Lukas, Andre
    Hypercharge flux in heterotic compactifications2015In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 91, no 4, article id 046008Article in journal (Refereed)
    Abstract [en]

    We study heterotic Calabi-Yau models with hypercharge flux breaking, where the visible E-8 gauge group is directly broken to the standard model group by a nonflat gauge bundle, rather than by a two-step process involving an intermediate grand unified theory and a Wilson line. It is shown that the required alternative E-8 embeddings of hypercharge, normalized as required for gauge unification, can be found and we classify these possibilities. However, for all but one of these embeddings we prove a general no-go theorem which asserts that no suitable geometry and vector bundle leading to a standard model spectrum can be found. Intuitively, this happens due to the large number of index conditions which have to be imposed in order to obtain a correct physical spectrum in the absence of an underlying grand unified theory.

  • 5. Anderson, Louise
    et al.
    Zarembo, Konstantin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Quantum phase transitions in mass-deformed ABJM matrix model2014In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 9, p. 021-Article in journal (Refereed)
    Abstract [en]

    When mass-deformed ABJM theory is considered on S-3, the partition function of the theory localises, and is given by a matrix model. At large N, we solve this model in the decompactification limit, where the radius of the three-sphere is taken to infinity. In this limit, the theory exhibits a rich phase structure with an infinite number of third-order quantum phase transitions, accumulating at strong coupling.

  • 6.
    Apruzzi, Fabio
    et al.
    Univ N Carolina, Dept Phys, Chapel Hill, NC 27599 USA; CUNY, Grad Ctr, Initiat Theoret Sci, New York, NY 10016 USA; olumbia Univ, Dept Phys, 538 W 120th St, New York, NY 10027 USA.
    Dibitetto, Giuseppe
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Tizzano, Luigi
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    A new 6d fixed point from holography2016In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 11, article id 126Article in journal (Refereed)
    Abstract [en]

    We propose a stringy construction giving rise to a class of interacting and non-supersymmetric CFT's in six dimensions. Such theories may be obtained as an IR conformal fixed point of an RG flow ending up in a (1,0)" role="presentation" style="display: inline; font-size: 13.6px; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; font-family: arial, verdana, sans-serif; position: relative;">(1,0)(1,0) theory in the UV. We provide the due holographic evidence in the context of massive type IIA on AdS7×M3" role="presentation" style="display: inline; font-size: 13.6px; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; font-family: arial, verdana, sans-serif; position: relative;">AdS7×M3AdS7×M3, where M3" role="presentation" style="display: inline; font-size: 13.6px; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; font-family: arial, verdana, sans-serif; position: relative;">M3M3 is topologically an S3" role="presentation" style="display: inline; font-size: 13.6px; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; font-family: arial, verdana, sans-serif; position: relative;">S3S3. In particular, in this paper we present a 10d flow solution which may be interpreted as a non-BPS bound state of NS5, D6 and D6¯" role="presentation" style="display: inline; font-size: 13.6px; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; font-family: arial, verdana, sans-serif; position: relative;">D6⎯⎯⎯⎯⎯⎯⎯D6¯ branes. Moreover, by adopting its 7d effective desciption, we are able to holographically compute the free energy and the operator spectrum in the novel IR conformal fixed point.

  • 7.
    Ashoorioon, Amjad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Exit from inflation with a first-order phase transition and a gravitational wave blast2015In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 747, p. 446-453Article in journal (Refereed)
    Abstract [en]

    In double-field inflation, which exploits two scalar fields, one of the fields rolls slowly during inflation whereas the other field is trapped in a meta-stable vacuum. The nucleation rate from the false vacuum to the true one becomes substantial enough that triggers a first order phase transition and ends inflation. We revisit the question of first order phase transition in an "extended" model of hybrid inflation, realizing the double-field inflationary scenario, and correctly identify the parameter space that leads to a first order phase transition at the end of inflation. We compute the gravitational wave profile which is generated during this first order phase transition. Assuming instant reheating, the peak frequency falls in the 1 GHz to 10 GHz frequency band and the amplitude varies in the range 10(-11) less than or similar to Omega(GW)h(2) <= 10(-8), depending on the value of the cosmological constant in the false vacuum. For a narrow band of vacuum energies, the first order phase transition can happen after the end of inflation via the violation of slow-roll, with a peak frequency that varies from 1 THz to 100 THz. For smaller values of cosmological constant, even though inflation can end via slow-roll violation, the universe gets trapped in a false vacuum whose energy drives a second phase of eternal inflation. This range of vacuum energies do not lead to viable inflationary models, unless the value of the cosmological constant is compatible with the observed value, M similar to 10(-3) eV.

  • 8.
    Ashoorioon, Amjad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Chialva, Diego
    Danielsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Effects of nonlinear dispersion relations on non-Gaussianities2011In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 6, p. 034-Article in journal (Refereed)
    Abstract [en]

    We investigate the effect of non-linear dispersion relations on the bispectrum. In particular, we study the case were the modified relations do not violate the WKB condition at early times, focusing on a particular example which is exactly solvable: the Jacobson-Corley dispersion relation with quartic correction with positive coefficient to the squared linear relation. We find that the corrections to the standard result for the bispectrum are suppressed by a factor H-2/p(c)(2) where p(c) is the scale where the modification to the dispersion relation becomes relevant. The modification is mildly configuration-dependent and equilateral configurations are more suppressed with respect to the local ones, by a factor of one percent. There is no configuration leading to enhancements. We then analyze the results in the framework of particle creation using the approximate gluing method of Brandenberger and Martin, which relates more directly to the modeling of the trans-Planckian physics via modifications of the vacuum at a certain cutoff scale. We show that the gluing method overestimates the leading order correction to the spectrum and bispectrum by one and two orders, respectively, in We discuss the various approximation and conclude that for dispersion relations not violating WKB at early times the particle creation is small and does not lead to enhanced contributions to the bispectrum. We also show that in many cases enhancements do not our when modeling the trans-Planckian physics via modifications of the vacuum at a certain cutoff scale. Most notably they are only of order O(1) when the Bogolyubov coefficients accounting for particle creation are determined by the Wronskian condition and the minimization of the uncertainty between the field and its conjugate momentum.

  • 9.
    Ashoorioon, Amjad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Sheikh-Jabbari, M. M.
    1/N resolution to inflationary eta-problem2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 713, no 4-5, p. 353-357Article in journal (Refereed)
    Abstract [en]

    We observe that the dominant one loop contribution to the graviton propagator in the theory of N (N >> 1) light scalar fields phi(a) (with masses smaller than M-pI/root N) minimally coupled to Einstein gravity is proportional to N while that of graviton-scalar-scalar interaction vertex is N independent. We use this to argue that the coefficient of the R phi(2)(a) term appearing at one loop level is 1/N suppressed. This observation provides a resolution to the quantum eta-problem, that the slow-roll parameter eta receives order one quantum loop corrections for inflationary models built within the framework of scalar fields minimally coupled to Einstein gravity, for models involving large number of fields. As particular examples, we employ this to argue in favor of the absence of eta-problem in multi-field inflationary scenarios of M-flation and N-flation.

  • 10.
    Ashoorioon, Amjad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Firouzjahi, Hassan
    Sheikh-Jabbari, Mohammmad Mahdi
    Matrix inflation and its string theory origins2010Conference paper (Refereed)
    Abstract [en]

    Motivated by the dynamics of N coincident D3 branes in some specific flux compactifications, we construct an inflationary model in which inflation is driven by three N Oe N hermitian matrices i,i = 1,2, 3, hence the name Matrix Inflation, or M-f lation for short. We show that one can consistently restrict the classical dynamics to a sector in which the i are proportional to the N Oe N irreducible representation of SU(2). In this sector our model behaves like an effective inflaton field, which t akes super-Planckian field values, and 3N(2) -' 1 isocurvature fields. These may have the observational effects such as production of iso-curvature perturbations on cosmic microwave background. Moreover, the existence of these extra scalars provides us wi th a natural preheating mechanism and exit from inflation. Due to the super-Planckian excursions of the canonical effective inflaton, the model is capable of producing a considerable amount of gravity waves that can be probed by future CMB polarization ex periments. Furthermore, the fine-tunings associated with unnaturally small couplings in the chaotic type inflationary scenarios are removed. We also show that even if the cutoff of the theory is lowered by the square of number of species, one can still us e the effective field theory approach to justify the absence of higher dimensional operators.

  • 11.
    Ashoorioon, Amjad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Sheikh-Jabbari, M. M.
    Gauged M-flation, its UV sensitivity and spectator species2011In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 6, p. 014-Article in journal (Refereed)
    Abstract [en]

    In this paper we study gauged M-flation. an inflationary model in which inflation is driven by three N x N scalar field matrices in the adjoint representation of U(N) gauge group. We focus our study on the gauged M-flation model which could be derived front the dynamics of a stack of D3-branes in appropriate background flux. The background inflationary dynamics is unaltered compared to the ungauged case of [1], while the spectrum of "spectator species", the isocurvature modes, differs from the ungauged case. Presence of a large number of spectators, although irrelevant to the slow-roll inflationary dynamics, has been argued to lower the effective UV cutoff Lambda of the theory from the Planck mass M-pl, putting into question the main advantage of M-flation in not having super-Planckian field values and unnaturally small couplings. Through a careful analysis of the spectrum of the spectators we argue that contrary to what happens in N-flation models, M-flation is still UV safe with the modified (reduced) effective UV cutoff Lambda, which we show to be of order (0.5 - 1) x 10(-1)M(pl). Moreover, we argue that the string scale in our gauged M-flation model is larger than Lambda by a factor of 10 and hence one can also neglect stringy effects. We also comment on the stability of classical inflationary paths in the gauged M-flation.

  • 12.
    Ashoorioon, Amjad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Shiu, Gary
    A note on calm excited states of inflation2011In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 3, p. 025-Article in journal (Refereed)
    Abstract [en]

    We identify a two-parameter family of excited states within slow-roll inflation for which either the corrections to the two-point function or the characteristic signatures of excited states in the three-point function - i.e. the enhancement for the flattened momenta configurations- are absent. These excited states may nonetheless violate the adiabaticity condition maximally. We dub these initial states of inflation calm excited states. We show that these two sets do not intersect, i.e., those that leave the power-spectrum invariant can be distinguished from their bispectra, and vice versa. The same set of calm excited states that leave the two-point function invariant for slow-roll inflation, do the same task for DBI inflation. However, at the level of three-point function, the calm excited states whose flattened configuration signature is absent for slow-roll inflation, will lead to an enhancement for DBI inflation generally, although the signature is smaller than what suggested by earlier analysis. This example also illustrates that imposing the Wronskian condition is important for obtaining a correct estimate of the non-Gaussian signatures.

  • 13.
    Azevedo, Thales
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Engelund, Oluf Tang
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Ambitwistor formulations of R2 gravity and (DF)2 gauge theories2017In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 11, article id 052Article in journal (Refereed)
    Abstract [en]

    We consider D-dimensional amplitudes in R-2 gravities (conformal gravity in D = 4) and in the recently introduced (DF)(2) gauge theory, from the perspective of the CHY formulae and ambitwistor string theory. These theories are related through the BCJ double-copy construction, and the (DF)(2) gauge theory obeys color-kinematics duality. We work out the worldsheet details of these theories and show that they admit a formulation as integrals on the support of the scattering equations, or alternatively, as ambitwistor string theories. For gravity, this generalizes the work done by Berkovits and Witten on conformal gravity to D dimensions. The ambitwistor is also interpreted as a D-dimensional generalization of Witten's twistor string (SYM + conformal supergravity). As part of our ambitwistor investigation, we discover another (DF)(2) gauge theory containing a photon that couples to Einstein gravity. This theory can provide an alternative KLT description of Einstein gravity compared to the usual Yang-Mills squared.

  • 14.
    Azevedo, Thales
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Jusinskas, Renann Lipinski
    AS CR, Inst Phys, Na Slovance 2, Prague 18221, Czech Republic..
    Background constraints in the infinite tension limit of the heterotic string2016In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 8, article id 133Article in journal (Refereed)
    Abstract [en]

    In this work we investigate the classical constraints imposed on the supergravity and super Yang-Mills backgrounds in the alpha' -> 0 limit of the heterotic string using the pure spinor formalism. Guided by the recently observed sectorization of the model, we show that all the ten-dimensional constraints are elegantly obtained from the single condition of nilpotency of the BRST charge.

  • 15.
    Azevedo, Thales
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Jusinskas, Renann Lipinski
    Inst Phys AS CR, Slovance 2, Prague 18221, Czech Republic.
    Connecting the ambitwistor and the sectorized heterotic strings2017In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 10, article id 216Article in journal (Refereed)
    Abstract [en]

    The sectorized description of the (chiral) heterotic string using pure spinors has been misleadingly viewed as an in finite tension string. One evidence for this fact comes from the tree level 3-point graviton amplitude, which we show to contain the usual Einstein term plus a higher curvature contribution. After reintroducing a dimensionful parameter l in the theory, we demonstrate that the heterotic model is in fact two-fold, depending on the choice of the supersymmetric sector, and that the spectrum also contains one massive (open string like) multiplet. By taking the limit l -> 1 infinity, we finally show that the ambitwistor string is recovered, reproducing the unexpected heterotic state in Mason and Skinner's RNS description.

  • 16. Babichenko, A.
    et al.
    Dekel, Amit
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Sax, O. O.
    Finite-gap equations for strings on AdS 3 times S 3 times T 4 with mixed 3-form flux2014In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 11, p. 122-Article in journal (Refereed)
    Abstract [en]

    We study superstrings on AdS 3 times S 3 times T 4 supported by a combination of Ramond-Ramond and Neveu-Schwarz-Neveu-Schwarz three form fluxes, and write down a set of finite-gap equations that describe the massive part of the classical string spectrum. Using the recently proposed all-loop S-matrix we write down the all-loop Bethe ansatz equations for the massive sector. In the thermodynamic limit the Bethe ansatz reproduces the finite-gap equations. As part of this derivation we propose expressions for the leading order dressing phases. These phases differ from the well-known Arutyunov-Frolov-Staudacher phase that appears in the pure Ramond-Ramond case. We also consider the one-loop quantisation of the algebraic curve and determine the one-loop corrections to the dressing phases. Finally we consider some classical string solutions including finite size giant magnons and circular strings.

  • 17.
    Bah, Ibrahima
    et al.
    Univ Calif San Diego, La Jolla, USA; Johns Hopkins Univ, Baltimore, USA.
    Passias, Achilleas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Tomasiello, Alessandro
    Univ Milano Bicocca, Milan, Italy; INFN, Milan, Italy.
    AdS(5) compactifications with punctures in massive IIA supergravity2017In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 11, article id 050Article in journal (Refereed)
    Abstract [en]

    We find AdS(5) solutions holographically dual to compactifications of six-dimensional N=(1,0) supersymmetric field theories on Riemann surfaces with punctures. We simplify a previous analysis of supersymmetric AdS(5) IIA solutions, and with a suitable Ansatz we find explicit solutions organized in three classes, where an O8-D8 stack, D6- and D4-branes are simultaneously present, localized and partially localized. The D4-branes are smeared over the Riemann surface and this is interpreted as the presence of a uniform distribution of punctures. For the first class we identify the corresponding six-dimensional theory as an E-string theory coupled to a quiver gauge theory. The second class of solutions lacks D6-branes and its central charge scales as n(5/2), suggesting a five-dimensional origin for the dual field theory. The last class has elements of the previous two.

  • 18.
    Bak, Dongsu
    et al.
    Univ Seoul, Phys Dept, Seoul 02504, South Korea..
    Gustafsson, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Five-dimensional fermionic Chern-Simons theory2018In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, article id 037Article in journal (Refereed)
    Abstract [en]

    We study 5d fermionic CS theory with a fermionic 2-form gauge potential. This theory can be obtained from 5d maximally supersymmetric YM theory by performing the maximal topological twist. We put the theory on a five-manifold and compute the partition function. We find that it is a topological quantity, which involves the Ray-Singer torsion of the five-manifold. For abelian gauge group we consider the uplift to the 6d theory and find a mismatch between the 5d partition function and the 6d index, due to the nontrivial dimensional reduction of a selfdual two-form gauge field on a circle. We also discuss an application of the 5d theory to generalized knots made of 2d sheets embedded in 5d.

  • 19. Balasubramanian, V.
    et al.
    Bernamonti, A.
    Craps, B.
    Keränen, V.
    Keski-Vakkuri, Esko
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Müller, B.
    Thorlacius, L.
    Vanhoof, J.
    Thermalization of the spectral function in strongly coupled two dimensional conformal field theories2013In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 4, p. 069-Article in journal (Refereed)
    Abstract [en]

    Using Wigner transforms of Green functions, we discuss non-equilibrium generalizations of spectral functions and occupation numbers. We develop methods for computing time-dependent spectral functions in conformal field theories holographically dual to thin-shell AdS-Vaidya spacetimes.

  • 20. Balasubramanian, V.
    et al.
    Bernamonti, A.
    de Boer, J.
    Copland, N.
    Craps, B.
    Keski-Vakkuri, Esko
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Mueller, B.
    Schaefer, A.
    Shigemori, M.
    Staessens, W.
    Holographic thermalization2011In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 84, no 2, p. 026010-Article in journal (Refereed)
    Abstract [en]

    Using the AdS/CFT correspondence, we probe the scale dependence of thermalization in strongly coupled field theories following a sudden injection of energy via calculations of two-point functions, Wilson loops, and entanglement entropy in d = 2, 3, 4. In the saddle-point approximation these probes are computed in AdS space in terms of invariant geometric objects-geodesics, minimal surfaces, and minimal volumes. Our calculations for two-dimensional field theories are analytical. In our strongly coupled setting, all probes in all dimensions share certain universal features in their thermalization: (1) a slight delay in the onset of thermalization, (2) an apparent nonanalyticity at the endpoint of thermalization, (3) top-down thermalization where the UV thermalizes first. For homogeneous initial conditions the entanglement entropy thermalizes slowest and sets a timescale for equilibration that saturates a causality bound over the range of scales studied. The growth rate of entanglement entropy density is nearly volume-independent for small volumes, but slows for larger volumes.

  • 21. Balasubramanian, V.
    et al.
    Bernamonti, A.
    de Boer, J.
    Craps, B.
    Franti, L.
    Galli, F.
    Keski-Vakkuri, Esko
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Mueller, B.
    Schaefer, A.
    Inhomogeneous holographic thermalization2013In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 10, p. 082-Article in journal (Refereed)
    Abstract [en]

    The sudden injection of energy in a strongly coupled conformal field theory and its subsequent thermalization can be holographically modeled by a shell falling into anti-de Sitter space and forming a black brane. For a homogeneous shell, Bhattacharyya and Minwalla were able to study this process analytically using a weak field approximation. Motivated by event-by-event fluctuations in heavy ion collisions, we include inhomogeneities in this model, obtaining analytic results in a long wavelength expansion. In the early-time window in which our approximations can be trusted, the resulting evolution matches well with that of a simple free streaming model. Near the end of this time window, we find that the stress tensor approaches that of second-order viscous hydrodynamics. We comment on possible lessons for heavy ion phenomenology.

  • 22. Balasubramanian, V.
    et al.
    Bernamonti, A.
    de Boer, J.
    Craps, B.
    Franti, L.
    Galli, F.
    Keski-Vakkuri, Esko
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Mueller, B.
    Schaefer, A.
    Inhomogeneous Thermalization in Strongly Coupled Field Theories2013In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 111, no 23, p. 231602-Article in journal (Refereed)
    Abstract [en]

    To describe theoretically the creation and evolution of the quark-gluon plasma, one typically employs three ingredients: a model for the initial state, nonhydrodynamic early time evolution, and hydrodynamics. In this Letter we study the nonhydrodynamic early time evolution using the AdS/CFT correspondence in the presence of inhomogeneities. We find that the AdS description of the early time evolution is well matched by free streaming. Near the end of the early time interval where our analytic computations are reliable, the stress tensor agrees with the second order hydrodynamic stress tensor computed from the local energy density and fluid velocity. Our techniques may also be useful for the study of far-from-equilibrium strongly coupled systems in other areas of physics.

  • 23. Balatsky, Alexander
    et al.
    Gudnason, Sven Bjarke
    Kedem, Yaron
    Krikun, Alexander
    Thorlacius, Larus
    Zarembo, Konstantin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Classical and quantum temperature fluctuations via holography2015In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 1, article id 011Article in journal (Refereed)
    Abstract [en]

    We study local temperature fluctuations in a 2+1 dimensional CFT on the sphere, dual to a black hole in asymptotically AdS spacetime. The fluctuation spectrum is governed by the lowest-lying hydrodynamic modes of the system whose frequency and damping rate determine whether temperature fluctuations are thermal or quantum. We calculate numerically the corresponding quasinormal frequencies and match the result with the hydrodynamics of the dual CFT at high temperature. As a by-product of our analysis we determine the appropriate boundary conditions for calculating low-lying quasinormal modes for a four-dimensional Reissner-Nordstrom black hole in global AdS.

  • 24.
    Banerjee, Souvik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Gaddam, Nava
    Univ Utrecht, Inst Theoret Phys, Princetonpl 5, NL-3584 CC Utrecht, Netherlands.;Univ Utrecht, Ctr Extreme Matter & Emergent Phenomena, Princetonpl 5, NL-3584 CC Utrecht, Netherlands..
    Mukhopadhyay, Ayan
    Vienna Univ Technol, Inst Theoret Phys, Wiedner Hauptstr 8-10, A-1040 Vienna, Austria.;CERN, Dept Theoret Phys, CH-1211 Geneva 23, Switzerland..
    Illustrated study of the semiholographic nonperturbative framework2017In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, no 6, article id 066017Article in journal (Refereed)
    Abstract [en]

    Semiholography has been proposed as an effective nonperturbative framework which can consistently combine perturbative and nonperturbative effects for theories like QCD. It is postulated that the strongly coupled nonperturbative sector has a holographic dual in the form of a classical gravity theory in the large N limit, and the perturbative fields determine the gravitational boundary conditions. In this work, we pursue a fundamental derivation of this framework particularly showing how perturbative physics by itself can determine the holographic dual of the infrared, and also the interactions between the perturbative and the holographic sectors. We firstly demonstrate that the interactions between the two sectors can be constrained through the existence of a conserved local energy-momentum tensor for the full system up to hard-soft coupling constants. As an illustration, we set up a biholographic toy theory where both the UV and IR sectors are strongly coupled and holographic with distinct classical gravity duals. In this construction, the requirement that an appropriate gluing can cure the singularities (geodetic incompleteness) of the respective geometries leads us to determine the parameters of the IR theory and the hard-soft couplings in terms of those of the UV theory. The high energy scale behavior of the hard-soft couplings is state-independent but their runnings turn out to be state-dependent. We discuss how our approach can be adapted to the construction of the semiholographic framework for QCD.

  • 25.
    Bargheer, Till
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Beisert, N.
    Loebbert, F.
    McLoughlin, T.
    Conformal anomaly for amplitudes in N =6 superconformal Chern-Simons theory2012In: Journal of Physics A: Mathematical and Theoretical, ISSN 1751-8113, E-ISSN 1751-8121, Vol. 45, no 47, p. 475402-Article in journal (Refereed)
    Abstract [en]

    Scattering amplitudes in three-dimensional N = 6 ChernSimons theory are shown to be non-invariant with respect to the free representation of the osp(6|4) symmetry generators. At tree and one-loop level these anomalous terms occur only for non-generic, singular configurations of the external momenta and can be used to determine the form of the amplitudes. In particular we show that the symmetries predict that the one-loop six-point amplitude is non-vanishing and confirm this by means of an explicit calculation using generalized unitarity methods. We comment on the implications of this finding for any putative Wilson loop/amplitude duality in N = 6 ChernSimons theory.

  • 26.
    Bargheer, Till
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Beisert, Niklas
    Loebbert, Florian
    Exact superconformal and Yangian symmetry of scattering amplitudes2011In: Journal of Physics A: Mathematical and Theoretical, ISSN 1751-8113, E-ISSN 1751-8121, Vol. 44, no 45, p. 454012-Article, review/survey (Refereed)
    Abstract [en]

    We review recent progress in the understanding of symmetries for scattering amplitudes in N = 4 superconformal Yang-Mills theory. It is summarized how the superficial breaking of superconformal symmetry by collinear anomalies and the renormalization process can be cured at tree and loop level. This is achieved by correcting the representation of the superconformal group on amplitudes. Moreover, we comment on the Yangian symmetry of scattering amplitudes and how it inherits these correction terms from the ordinary Lie algebra symmetry. Invariants under this algebra and their relation to the Gra(sis)mannian generating function for scattering amplitudes are discussed. Finally, parallel developments in N = 6 superconformal Chern-Simons theory are summarized. This paper is an invited review for a special issue of Journal of Physics A: Mathematical and Theoretical devoted to 'Scattering amplitudes in gauge theories'.

  • 27.
    Bargheer, Till
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    He, Song
    McLoughlin, Tristan
    New Relations for Three-Dimensional Supersymmetric Scattering Amplitudes2012In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 108, no 23, p. 231601-Article in journal (Refereed)
    Abstract [en]

    We provide evidence for a duality between color and kinematics in three-dimensional supersymmetric Chern-Simons matter theories. We show that the six-point amplitude in the maximally supersymmetric N = 8 theory can be arranged so that the kinematic factors satisfy the fundamental identity of three-algebras. We further show that the four- and six-point N = 8 amplitudes can be squared into the amplitudes of N = 16 three-dimensional supergravity, thus providing evidence for a hidden three-algebra structure in the dynamics of the supergravity.

  • 28. Bargheer, Till
    et al.
    Minahan, Joseph A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Pereira, Raul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Computing Three-Point Functions for Short Operators2014In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 3, p. 096-Article in journal (Refereed)
    Abstract [en]

    We compute the three-point structure constants for short primary operators of N=4 super Yang-Mills theory to leading order in the inverse coupling by mapping the problem to a flat-space string theory calculation. We check the validity of our procedure by comparing to known results for three chiral primaries. We then compute the three-point functions for any combination of chiral and non-chiral primaries, with the non-chiral primaries all dual to string states at the first massive level. Along the way we find many cancellations that leave us with simple expressions, suggesting that integrability is playing an important role.

  • 29.
    Baum, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    On the metastability of the Standard Model2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the discovery of a particle consistent with the Standard Model (SM) Higgs at the Large Hadron Collider (LHC) at CERN in 2012, the final ingredient of the SM has been found. The SM provides us with a powerful description of the physics of fundamental particles, holding up at all energy scales we can probe with accelerator based experiments. However, astrophysics and cosmology show us that the SM is not the final answer, but e.g. fails to describe dark matter and massive neutrinos. Like any non-trivial quantum field theory, the SM must be subject to a so-called renormalization procedure in order to extrapolate the model between different energy scales. In this context, new problems of more theoretical nature arise, e.g. the famous hierarchy problem of the Higgs mass. Renormalization also leads to what is known as the metastability problem of the SM: assuming the particle found at the LHC is the SM Higgs boson, the potential develops a second minimum deeper than the electroweak one in which we live, at energy scales below the Planck scale. Absolute stability all the way up to the Planck scale is excluded at a confidence level of about 98 %. For the central experimental SM values the instability occurs at scales larger than ~ 10¹⁰ GeV.

    One can take two viewpoints regarding this instability: assuming validity of the SM all the way up to the Planck scale, the problem does not necessarily lead to an inconsistency of our existence. If we assume our universe to have ended up in the electroweak minimum after the Big Bang, the probability that it would have transitioned to its true minimum during the lifetime of the universe is spectacularly small.  If we on the other hand demand absolute stability, new physics must modify the SM at or below the instability scale of ~ 10¹⁰ GeV, and we can explore which hints the instability might provide us with on this new physics.

    In this work, the metastability problem of the SM and possible implications are revisited. We give an introduction to the technique of renormalization and apply this to the SM. We then discuss the stability of the SM potential and the hints this might provide us with on new physics at large scales.

  • 30.
    Baum, Sebastian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Cantatore, G.
    Hoffmann, D. H. H.
    Karuza, M.
    Semertzidis, Y. K.
    Upadhye, A.
    Zioutas, K.
    Detecting solar chameleons through radiation pressure2014In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 739, p. 167-173Article in journal (Refereed)
    Abstract [en]

    Light scalar fields can drive the accelerated expansion of the universe. Hence, they are obvious dark energy candidates. To make such models compatible with tests of General Relativity in the solar system and "fifth force" searches on Earth, one needs to screen them. One possibility is the so-called "chameleon" mechanism, which renders an effective mass depending on the local matter density. If chameleon particles exist, they can be produced in the sun and detected on Earthexploiting the equivalent of a radiation pressure. Since their effective mass scales with the local matter density, chameleons can be reflected by a dense medium if their effective mass becomes greater than their total energy. Thus, under appropriate conditions, a flux of solar chameleons may be sensed by detecting the total instantaneous momentum transferred to a suitable opto-mechanical force/pressure sensor. We calculate the solar chameleon spectrum and the reach in the chameleon parameter space of an experiment using the preliminary results from a force/pressure sensor, currently under development at INFN Trieste, to be mounted in the focal plane of one of the X-Ray telescopes of the CAST experiment at CERN. We show, that such an experiment signifies a pioneering effort probing uncharted chameleon parameter space.

  • 31. Beisert, Niklas
    et al.
    Ahn, Changrim
    Alday, Luis
    Bajnok, Zoltan
    Drummond, James M.
    Freyhult, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Gromov, Nikolay
    Janik, Romuald A.
    Kazakov, Vladimir
    Klose, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Korchemsky, Gregory P
    Kristjansen, Charlotte
    Magro, Marc
    McLoughlin, Tristan
    Minahan, Joseph A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Nepomechie, Rafael I.
    Rej, Adam
    Roiban, Radu
    Schäfer-Nameki, Sakura
    Sieg, Christoph
    Staudacher, Matthias
    Torrielli, Alessandro
    Tseytlin, Arkady A.
    Vieira, Pedro
    Volin, Dmytro
    Zoubos, Konstantinos
    Review of AdS/CFT Integrability: An Overview2012In: Letters in Mathematical Physics, ISSN 0377-9017, E-ISSN 1573-0530, Vol. 99, no 1-3, p. 3-32Article, review/survey (Refereed)
    Abstract [en]

    This is the introductory chapter of a review collection on integrability in the context of the AdS/CFT correspondence. In the collection we present an overview of the achievements and the status of this subject as of the year 2010.

  • 32. Beisert, Niklas
    et al.
    Freyhult, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Fluctuations and energy shifts in the Bethe ansatz.2005In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 622, no 3-4, p. 343-348Article in journal (Refereed)
  • 33.
    Belyaev, A. K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Lebedev, O. V.
    Nonadiabatic nuclear dynamics of atomic collisions based on branching classical trajectories2012In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 388, no 9, p. 092007-Article in journal (Refereed)
    Abstract [en]

    The nonadiabatic nuclear dynamics of low-energy Na + H collisions is studied by the branching classical trajectory approach. The calculated inelastic cross sections are in good agreement with the results of full quantum calculations.

  • 34. Bena, I.
    et al.
    Blåbäck, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Van Riet, T.
    Antibranes cannot become black2013In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 87, no 10, p. 104023-Article in journal (Refereed)
    Abstract [en]

    When D-branes are inserted in flux backgrounds of opposite charge, the resulting solution has a certain singularity in the fluxes. Recently it has been argued, using numerical solutions, that for anti-D3 branes in the Klebanov-Strassler background, these singularities cannot be cloaked by a horizon, which strongly suggests they are not physical. In this paper we provide an analytic proof that the singularity of all codimension-three antibrane solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3 branes smeared on the T-3 of R-3 x T-3 with fluxes) cannot be hidden behind a horizon and that the charge of black branes with smooth event horizons must have the same sign as the charge of the flux background. Our result indicates that infinitesimally blackening the antibranes immediately triggers brane-flux annihilation and strengthens the intuition that antibranes placed in flux with positive charge immediately annihilate against it.

  • 35.
    Bern, Zvi
    et al.
    UCLA, Dept Phys & Astron, Mani L Bhaumik Inst Theoret Phys, Los Angeles, CA 90095 USA..
    Carrasco, John Joseph
    CEA Saclay, Inst Phys Theor, F-91191 Gif Sur Yvette, France..
    Chen, Wei-Ming
    UCLA, Dept Phys & Astron, Mani L Bhaumik Inst Theoret Phys, Los Angeles, CA 90095 USA..
    Johansson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. KTH Royal Inst Technol, Nordita, Roslagstullsbacken 23, S-10691 Stockholm, Sweden.;Stockholm Univ, Roslagstullsbacken 23, S-10691 Stockholm, Sweden..
    Roiban, Radu
    Penn State Univ, Inst Gravitat & Cosmos, University Pk, PA 16802 USA..
    Gravity Amplitudes as Generalized Double Copies of Gauge-Theory Amplitudes2017In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 118, no 18, article id 181602Article in journal (Refereed)
    Abstract [en]

    Whenever the integrand of a gauge-theory loop amplitude can be arranged into a form where the Bern-Carrasco-Johansson duality between color and kinematics is manifest, a corresponding gravity integrand can be obtained simply via the double-copy procedure. However, finding such gauge-theory representations can be challenging, especially at high loop orders. Here, we show that we can, instead, start from generic gauge-theory integrands, where the duality is not manifest, and apply a modified double-copy procedure to obtain gravity integrands that include contact terms generated by violations of dual Jacobi identities. We illustrate this with three-, four- and five-loop examples in N = 8 supergravity.

  • 36.
    Bern, Zvi
    et al.
    University of California Los Angeles, Department of Physics and Astronomy, Mani L. Bhaumik Institute for Theoretical Physics.
    Carrasco, John Joseph
    CEA-Saclay, Institute of Theoretical Physics (IPhT); University of Paris-Saclay.
    Chen, Wei-Ming
    University of California Los Angeles, Department of Physics and Astronomy, Mani L. Bhaumik Institute for Theoretical Physics.
    Johansson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Stockholm University, Nordita; KTH Royal Institute of Technology.
    Roiban, Radu
    Pennsylvania State University, Institute for Gravitation and the Cosmos.
    Zeng, Mao
    University of California Los Angeles, Department of Physics and Astronomy, Mani L. Bhaumik Institute for Theoretical Physics.
    Five-loop four-point integrand of N=8 supergravity as a generalized double copy2017In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, no 12, article id 126012Article in journal (Refereed)
    Abstract [en]

    We use the recently developed generalized double-copy procedure to construct an integrand for the fiveloop four-point amplitude of N = 8 supergravity. This construction starts from a naive double copy of the previously computed corresponding amplitude of N = 4 super-Yang-Mills theory. This is then systematically modified by adding contact terms generated in the context of the method of maximal unitarity cuts. For the simpler generalized cuts, whose corresponding contact terms tend to be the most complicated, we derive a set of formulas relating the contact contributions to the violations of the dual Jacobi identities in the relevant gauge-theory amplitudes. For more complex generalized unitarity cuts, which tend to have simpler contact terms associated with them, we use the method of maximal cuts more directly. The five-loop fourpoint integrand is a crucial ingredient towards future studies of ultraviolet properties of N = 8 supergravity at five loops and beyond. We also present a nontrivial check of the consistency of the integrand, based on modern approaches for integrating over the loop momenta in the ultraviolet region.

  • 37.
    Bidermane, Ieva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Brumboiu, Iulia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Totani, Roberta
    University of L'Aquila.
    Grazioli, Cesare
    University of Trieste.
    Shariati Nilsson, Masumeh Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Herper, Heike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ressel, B
    Univ Nova Gorica, Ajdovscina 5270, Slovenia.
    de Simone, Monica
    Lozzi, Luca
    University of L'Aquila.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Atomic Contributions to the Valence Band Photoelectron Spectra of Metal-free, Iron and Manganese Phthalocyanines2015In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 205, p. 92-97Article, review/survey (Other academic)
    Abstract [en]

    The present work reports a photoelectron spectroscopy study of the low-energy region of the valence band of metal-free phthalocyanine (H2Pc) compared with those of iron phthalocyanine (FePc) and manganese phthalocyanine (MnPc). We have analysed in detail the atomic orbital composition of the valence band both experimentally, by making use of the variation in photoionization cross-sections with photon energy, and theoretically, by means of density functional theory. The atomic character of the Highest Occupied Molecular Orbital (HOMO), reflected on the outermost valence band binding energy region, is different for MnPc as compared to the other two molecules. The peaks related to the C 2p contributions, result in the HOMO for H2Pc and FePc and in the HOMO-1 for MnPc as described by the theoretical predictions, in very good agreement with the experimental results. The DFT simulations, discerning the atomic contribution to the density of states, indicate how the central metal atom interacts with the C and N atoms of the molecule, giving rise to different partial and total density of states for these three Pc molecules.

  • 38.
    Björk, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Fluctuations in the CMB through inflation2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal of this project is to gain a better understanding of the temperature fluctuations observed in the CMB. This goal is reached with the aid of a literature study. The report touches upon the origin of the CMB as well as how it is measured, mentioning and explaining relevant concepts such as recombination, photon decoupling, black body radiation, angular power spectrum etc. It is also specified that the temperature of the CMB is not uniform but varies slightly. The fact that these fluctuations show inhomogeneities at the early universe is emphasized as well as the need for a satisfying theory that explains said fluctuations. By presenting and employing inflation theory in combination with quantum mechanics, we show how such a theory can be obtained. Through extensive calculation we show how the primordial power spectrum for zero-point fluctuations during inflation is obtained and how it can be related to the time of recombination through a transfer function, thus explaining the existence of fluctuations in the CMB.

  • 39.
    Blåbäck, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Note on M2-branes in opposite charge2014In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 89, no 6, p. 065004-Article in journal (Refereed)
    Abstract [en]

    The flux singularity that arises for branes in oppositely charged fluxes is a widely discussed issue and in this paper the problem is investigated further. New AdS world volume (anti-)M2-brane solutions are constructed using space-filling branes placed in fluxes of opposite dissolved charge that is opposite to that of the brane. A topological obstruction is derived to show how the singularity develops during localization of this solution and any similarly constructed solution. Furthermore it is shown that it is not possible to hide the singularity behind a horizon, which would have given credence to an M theory resolution.

  • 40.
    Blåbäck, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Singular Fluxes in Ten and Eleven Dimensions: Sources, Singularities, Fluxes and Spam2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The energy content of our present universe is dominated by the dark-energy, or vacuum energy, which provides accelerated cosmic expansion. Dark energy has a possible effective explanation through a positive cosmological constant. The problem present in any fundamental theory is to explain the underlying dynamics of what gives rise to the cosmological constant.

    In string theory there are several scenarios that could give insight into what is behind the positive cosmological constant. One such construction uses anti-branes to achieve a net positive energy density of the vacuum. Anti-branes refers in this case to branes placed in a background with oppositely charged flux. As backreaction and localisation procedures are considered for anti-brane constructions a certain kind of singularity arise. This new type of singularity is present in the surrounding flux, which is not directly sourced by the brane.

    This thesis, and the works contained, considers several aspects of this type of singularity. The first such flux singularity were discovered for the anti-D3-branes, in which the approximations and assumptions of partial smearing and perturbative expansions are used. Included in this thesis are new anti-D6-brane solutions which are placed in oppositely charged flux. It is shown that after the anti-D6-branes are localised, they display the same type of singularity. The strength of this result lies in that it is possible to show the presence of the singularity beyond partial smearing and perturbative expansions. Similar to the anti-D6-brane solutions, new anti-M2-brane solutions are presented. These solutions are also argued to display the same type of singularity.

    The investigation into the presence of the singularity is just the first step. The second step is to deduce whether this singularity is acceptable and can somehow be resolved. Included in this thesis are two works that considers exactly this. One way of interpreting the singularity is through the absence of a no-force condition between the brane and the surrounding flux. This interpretation leads to the conclusion that the singularity is present due to the use of static Ansätze in a system that is inherently time dependent. Through an adiabatic approach it is here argued that this interpretation leads to a new type of instability.

    Another way of arguing for a possible resolution of this singularity is whether or not the singularity can be cloaked by an event horizon. This condition have been successful in other systems with singularities. It is argued in this thesis that it is not possible to hide the flux singularity behind a horizon. This leads to one out of two conclusions, either the condition is not a necessary one and the singularity can be resolved in a static manner, or the singularity does not have a resolution.

    To put these works in context the current singularities from anti-branes program is briefly reviewed to give a full overview of the current situation of these investigations.

    List of papers
    1. Smeared versus localised sources in flux compactifications
    Open this publication in new window or tab >>Smeared versus localised sources in flux compactifications
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    2010 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 12, p. 043-Article in journal (Refereed) Published
    Abstract [en]

    We investigate whether vacuum solutions in flux compactifications that are obtained with smeared sources (orientifolds or D-branes) still survive when the sources are localised. This seems to rely on whether the solutions are BPS or not. First we consider two sets of BPS solutions that both relate to the GKP solution through T-dualities: (p + 1)-dimensional solutions from spacetime-filling Op-planes with a conformally Ricci-flat internal space, and p-dimensional solutions with Op-planes that wrap a 1-cycle inside an everywhere negatively curved twisted torus. The relation between the solution with smeared orientifolds and the localised version is worked out in detail. We then demonstrate that a class of non-BPS AdS(4) solutions that exist for IASD fluxes and with smeared D3-branes (or analogously for ISD fluxes with anti-D3-branes) does not survive the localisation of the (anti) D3-branes. This casts doubts on the stringy consistency of non-BPS solutions that are obtained in the limit of smeared sources.

    Keywords
    Flux compactifications, Superstring Vacua, D-branes
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-148934 (URN)10.1007/JHEP12(2010)043 (DOI)000285964400003 ()
    Available from: 2011-03-15 Created: 2011-03-14 Last updated: 2017-12-11Bibliographically approved
    2. The problematic backreaction of SUSY-breaking branes
    Open this publication in new window or tab >>The problematic backreaction of SUSY-breaking branes
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    2011 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 8, p. 105-Article in journal (Refereed) Published
    Abstract [en]

    In this paper we investigate the localisation of SUSY-breaking branes which, in the smeared approximation, support specific non-BPS vacua. We show, for a wide class of boundary conditions, that there is no flux vacuum when the branes are described by a genuine delta-function. Even more, we find that the smeared solution is the unique solution with a regular brane profile. Our setup consists of a non-BPS AdS(7) solution in massive IIA supergravity with smeared anti-D6-branes and fluxes T-dual to ISD fluxes in IIB supergravity.

    Keywords
    Flux compactifications, Superstring Vacua, D-branes, dS vacua in string theory
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-161759 (URN)10.1007/JHEP08(2011)105 (DOI)000294901200056 ()
    Available from: 2011-11-21 Created: 2011-11-17 Last updated: 2017-12-08Bibliographically approved
    3. (Anti-)brane backreaction beyond perturbation theory
    Open this publication in new window or tab >>(Anti-)brane backreaction beyond perturbation theory
    Show others...
    2012 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2012, no 2, p. 025-Article in journal (Refereed) Published
    Abstract [en]

    We improve on the understanding of the backreaction of anti-D6-branes in a flux background that is mutually BPS with D6-branes. This setup is analogous to the study of the backreaction of anti-D3-branes inserted in the KS throat, but does not require us to smear the anti-branes or do a perturbative analysis around the BPS background. We solve the full equations of motion near the anti-D6-branes and show that only two boundary conditions are consistent with the equations of motion. Upon invoking a topological argument we eliminate the boundary condition with regular H flux since it cannot lead to a solution that approaches the right kind of flux away from the anti-D6-branes. This leaves us with a boundary condition which has singular, but integrable, H flux energy density.

    Keywords
    Flux compactifications, dS vacua in string theory, Superstring Vacua, D-branes
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-174603 (URN)10.1007/JHEP02(2012)025 (DOI)000301451200025 ()
    Available from: 2012-05-24 Created: 2012-05-22 Last updated: 2017-12-07Bibliographically approved
    4. Resolving anti-brane singularities through time-dependence
    Open this publication in new window or tab >>Resolving anti-brane singularities through time-dependence
    2013 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 2, p. 61-Article in journal (Refereed) Published
    Abstract [en]

    In this note we discuss a possible resolution of the flux singularities associated with the insertion of branes in backgrounds supported by fluxes that carry charges opposite to the branes. We present qualitative arguments that such a setup could be unstable both in the closed and open string sector. The singularities in the fluxes then get naturally resolved by taking the true solution to be a time-dependent process in which flux gets attracted towards the brane and subsequently annihilates.In this note we discuss a possible resolution of the flux singularities associated with the insertion of branes in backgrounds supported by fluxes that carry charges opposite to the branes. We present qualitative arguments that such a setup could be unstable both in the closed and open string sector. The singularities in the fluxes then get naturally resolved by taking the true solution to be a time-dependent process in which flux gets attracted towards the brane and subsequently annihilates.

    Keywords
    open string, membrane model, singularity, time dependence, flux, background, resolution
    National Category
    Subatomic Physics
    Research subject
    Theoretical Physics
    Identifiers
    urn:nbn:se:uu:diva-196357 (URN)10.1007/JHEP02(2013)061 (DOI)000316272900061 ()
    Available from: 2013-03-08 Created: 2013-03-08 Last updated: 2017-12-06Bibliographically approved
    5. Antibranes cannot become black
    Open this publication in new window or tab >>Antibranes cannot become black
    2013 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 87, no 10, p. 104023-Article in journal (Refereed) Published
    Abstract [en]

    When D-branes are inserted in flux backgrounds of opposite charge, the resulting solution has a certain singularity in the fluxes. Recently it has been argued, using numerical solutions, that for anti-D3 branes in the Klebanov-Strassler background, these singularities cannot be cloaked by a horizon, which strongly suggests they are not physical. In this paper we provide an analytic proof that the singularity of all codimension-three antibrane solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3 branes smeared on the T-3 of R-3 x T-3 with fluxes) cannot be hidden behind a horizon and that the charge of black branes with smooth event horizons must have the same sign as the charge of the flux background. Our result indicates that infinitesimally blackening the antibranes immediately triggers brane-flux annihilation and strengthens the intuition that antibranes placed in flux with positive charge immediately annihilate against it.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-203294 (URN)10.1103/PhysRevD.87.104023 (DOI)000319284100005 ()
    Available from: 2013-07-09 Created: 2013-07-08 Last updated: 2017-12-06Bibliographically approved
    6. Note on M2-branes in opposite charge
    Open this publication in new window or tab >>Note on M2-branes in opposite charge
    2014 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 89, no 6, p. 065004-Article in journal (Refereed) Published
    Abstract [en]

    The flux singularity that arises for branes in oppositely charged fluxes is a widely discussed issue and in this paper the problem is investigated further. New AdS world volume (anti-)M2-brane solutions are constructed using space-filling branes placed in fluxes of opposite dissolved charge that is opposite to that of the brane. A topological obstruction is derived to show how the singularity develops during localization of this solution and any similarly constructed solution. Furthermore it is shown that it is not possible to hide the singularity behind a horizon, which would have given credence to an M theory resolution.

    National Category
    Other Physics Topics
    Identifiers
    urn:nbn:se:uu:diva-220841 (URN)10.1103/PhysRevD.89.065004 (DOI)000333106900011 ()
    Available from: 2014-03-21 Created: 2014-03-21 Last updated: 2017-12-05Bibliographically approved
  • 41.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Borghese, A.
    Haque, S. S.
    Power-law cosmologies in minimal and maximal gauged supergravity2013In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 6, p. 107-Article in journal (Refereed)
    Abstract [en]

    In this paper we search for accelerating power-law solutions and ekpyrotic solutions within minimal and maximal four dimensional supergravity theories. We focus on the STU model for N = 1 and on the new CSO(p, q, r) theories, which were recently obtained exploiting electromagnetic duality, for N = 8. In the minimal case we find some new ekpyrotic solutions, while in the maximal case we find some new generic power-law solutions. We do not find any new accelerating solutions for these models.

  • 42.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Dibitetto, Giuseppe
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Accelerated Universes from type IIA Compactifications2014In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 003Article in journal (Other academic)
    Abstract [en]

    We study slow-roll accelerating cosmologies arising from geometric compactifications of type IIA string theory on T^6/(Z_2 x Z_2). With the aid of a genetic algorithm, we are able to find quasi-de Sitter backgrounds with both slow-roll parameters of order 0.1

  • 43.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Dibitetto, Giuseppe
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Fully stable dS vacua from generalised fluxes2013In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 8, p. 054-Article in journal (Refereed)
    Abstract [en]

    We investigate the possible existence of (meta-)stable de Sitter vacua within \cN=1 compactifications with generalised fluxes. With the aid of an algorithm inspired by the method of differential evolution, we were able to find three novel examples of completely tachyon-free de Sitter extrema in a non-isotropic type IIB model with non-geometric fluxes. We also analyse the surroundings of the aforementioned points in parameter space and chart the corresponding stability regions. These happen to occur at small values of the cosmological constant compared to the AdS scale.

  • 44.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Junghans, D.
    Van Riet, T.
    Vargas, Sergio C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Localised anti-branes in non-compact throats at zero and finite T2015In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 2, article id 018Article in journal (Refereed)
    Abstract [en]

    We investigate the 3-form singularities that are typical to anti-brane solutions in supergravity and check whether they can be cloaked by a finite temperature horizon. For anti-D3-branes in the Klebanov-Strassler background, this was already shown numerically to be impossible when the branes are partially smeared. In this paper, we present analytic arguments that also localised branes remain with singular 3-form fluxes at both zero and finite temperature. These results may have important, possibly fatal, consequences for constructions of meta-stable de Sitter vacua through uplifting.

  • 45.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Junghans, Daniel
    Van Riet, Thomas
    Wrase, Timm
    Zagermann, Marco
    (Anti-)brane backreaction beyond perturbation theory2012In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2012, no 2, p. 025-Article in journal (Refereed)
    Abstract [en]

    We improve on the understanding of the backreaction of anti-D6-branes in a flux background that is mutually BPS with D6-branes. This setup is analogous to the study of the backreaction of anti-D3-branes inserted in the KS throat, but does not require us to smear the anti-branes or do a perturbative analysis around the BPS background. We solve the full equations of motion near the anti-D6-branes and show that only two boundary conditions are consistent with the equations of motion. Upon invoking a topological argument we eliminate the boundary condition with regular H flux since it cannot lead to a solution that approaches the right kind of flux away from the anti-D6-branes. This leaves us with a boundary condition which has singular, but integrable, H flux energy density.

  • 46.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Junghans, Daniel
    Van Riet, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Wrase, Timm
    Zagermann, Marco
    Smeared versus localised sources in flux compactifications2010In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 12, p. 043-Article in journal (Refereed)
    Abstract [en]

    We investigate whether vacuum solutions in flux compactifications that are obtained with smeared sources (orientifolds or D-branes) still survive when the sources are localised. This seems to rely on whether the solutions are BPS or not. First we consider two sets of BPS solutions that both relate to the GKP solution through T-dualities: (p + 1)-dimensional solutions from spacetime-filling Op-planes with a conformally Ricci-flat internal space, and p-dimensional solutions with Op-planes that wrap a 1-cycle inside an everywhere negatively curved twisted torus. The relation between the solution with smeared orientifolds and the localised version is worked out in detail. We then demonstrate that a class of non-BPS AdS(4) solutions that exist for IASD fluxes and with smeared D3-branes (or analogously for ISD fluxes with anti-D3-branes) does not survive the localisation of the (anti) D3-branes. This casts doubts on the stringy consistency of non-BPS solutions that are obtained in the limit of smeared sources.

  • 47.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Junghans, Daniel
    Van Riet, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Wrase, Timm
    Zagermann, Marco
    The problematic backreaction of SUSY-breaking branes2011In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 8, p. 105-Article in journal (Refereed)
    Abstract [en]

    In this paper we investigate the localisation of SUSY-breaking branes which, in the smeared approximation, support specific non-BPS vacua. We show, for a wide class of boundary conditions, that there is no flux vacuum when the branes are described by a genuine delta-function. Even more, we find that the smeared solution is the unique solution with a regular brane profile. Our setup consists of a non-BPS AdS(7) solution in massive IIA supergravity with smeared anti-D6-branes and fluxes T-dual to ISD fluxes in IIB supergravity.

  • 48.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Danielsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Van Riet, Thomas
    Resolving anti-brane singularities through time-dependence2013In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 2, p. 61-Article in journal (Refereed)
    Abstract [en]

    In this note we discuss a possible resolution of the flux singularities associated with the insertion of branes in backgrounds supported by fluxes that carry charges opposite to the branes. We present qualitative arguments that such a setup could be unstable both in the closed and open string sector. The singularities in the fluxes then get naturally resolved by taking the true solution to be a time-dependent process in which flux gets attracted towards the brane and subsequently annihilates.In this note we discuss a possible resolution of the flux singularities associated with the insertion of branes in backgrounds supported by fluxes that carry charges opposite to the branes. We present qualitative arguments that such a setup could be unstable both in the closed and open string sector. The singularities in the fluxes then get naturally resolved by taking the true solution to be a time-dependent process in which flux gets attracted towards the brane and subsequently annihilates.

  • 49.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Janssen, B.
    Van Riet, T.
    Vercnocke, B.
    Fractional branes, warped compactifications and backreacted orientifold planes2012In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2012, no 10Article in journal (Refereed)
    Abstract [en]

    The standard extremal p-brane solutions in supergravity are known to allow for a generalisation which consists of adding a linear dependence on the worldvolume coordinates to the usual harmonic function. In this note we demonstrate that remarkably this generalisation goes through in exactly the same way for p-branes with fluxes added to it that correspond to fractional p-branes. We relate this to warped orientifold compactifications by trading the Dp-branes for Op-planes that solve the RR tadpole condition. This allows us to interpret the worldvolume dependence as due to lower-dimensional scalars that flow along the massless directions in the no-scale potential. Depending on the details of the fluxes these flows can be supersymmetric domain wall flows. Our solutions provide explicit examples of backreacted orientifold planes in compactifications with non-constant moduli.

  • 50.
    Blåbäck, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Janssen, Bert
    Van Riet, Thomas
    Vercnocke, Bert
    BPS domain walls from backreacted orientifolds2014In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, p. 040-Article in journal (Refereed)
    Abstract [en]

    Compactifications with D-brane and orientifold sources lead to standard gauged supergravity theories if the sources are smeared over the internal directions. It is therefore of interest to find how the solutions described by the gauged supergravity are altered by properly localising the sources. In this paper we analyse this for BPS domain wall solutions in the seven-dimensional gauged supergravity obtained from an O6 toroidal orientifold in massive IIA supergravity. This is one of the simplest no-scale supergravities that can be constructed and analysed in full detail. We find the BPS domain walls when the O6 planes are smeared. When the O6 planes are localised the domain wall solutions live in a warped compactification and we present the first-order equations these domain walls obey in 10 dimensions. In order to get explicit expressions we also consider the non-compact versions of the solutions for which the O6 planes have been traded for D6 branes and we recover the gauged supergravity expressions for the domain walls in the leading terms of the warp factor. Through T-duality we obtain partially localised solutions for compactifications to four dimensions using O3 planes with 3-form fluxes.

1234567 1 - 50 of 442
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