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  • 1.
    Alexeev, Anton
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Theoretical Physics.
    Polychronakos, Alexios
    Smedbäck, Mikael
    Department of Theoretical Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Theoretical Physics.
    Remarks on the black hole entropy and Hawking spectrum in Loop Quantum Gravity2005In: Physical Review D, Vol. 71, p. 067501-Article in journal (Refereed)
    Abstract [en]

    In this note we reply to the criticism by Corichi concerning our proposal for an equidistant area spectrum in loop quantum gravity. We further comment on the emission properties of black holes and on the statistics of links.

  • 2. Beisert, Niklas
    et al.
    Feretti, Gabriele
    Heise, Reiner
    Zarembo, Konstantin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    One-Loop QCD Spin Chain and its Spectrum2005In: Nuclear Physics B, Vol. 717, p. 137-189Article in journal (Refereed)
    Abstract [en]

    We study the renormalization of gauge invariant operators in large Nc QCD. We compute the complete matrix of anomalous dimensions to leading order in the 't Hooft coupling and study its eigenvalues. Thinking of the mixing matrix as the Hamiltonian of a generalized spin chain we find a large integrable sector consisting of purely gluonic operators constructed with self-dual field strengths and an arbitrary number of derivatives. This sector contains the true ground state of the spin chain and all the gapless excitations above it. The ground state is essentially the anti-ferromagnetic ground state of a XXX1 spin chain and the excitations carry either a chiral spin quantum number with relativistic dispersion relation or an anti-chiral one with non-relativistic dispersion relation.

  • 3. Beisert, Niklas
    et al.
    Kazakov, V. A.
    Sakai, K.
    Zarembo, Konstantin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    Complete spectrum of long operators in N=4 SYM at one loop2005In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 0507, p. 030-Article in journal (Refereed)
    Abstract [en]

    We construct the complete spectral curve for an arbitrary local operator, including fermions and covariant derivatives, of one-loop N=4 gauge theory in the thermodynamic limit. This curve perfectly reproduces the Frolov-Tseytlin limit of the full spectral curve of classical strings on AdS_5xS^5 derived in hep-th/0502226. To complete the comparison we introduce stacks, novel bound states of roots of different flavors which arise in the thermodynamic limit of the corresponding Bethe ansatz equations. We furthermore show the equivalence of various types of Bethe equations for the underlying su(2,2|4) superalgebra, in particular of the type "Beauty" and "Beast".

  • 4. Beisert, Niklas
    et al.
    Kazakov, V.A.
    Sakai, K.
    Zarembo, Konstantin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    The Algebraic Curve of Classical Superstrings on AdS_5xS^52006In: Communications in Mathematical Physics, Vol. 263, p. 659-710Article in journal (Refereed)
    Abstract [en]

    We investigate the monodromy of the Lax connection for classical IIB superstrings on AdS_5xS^5. For any solution of the equations of motion we derive a spectral curve of degree 4+4. The curve consists purely of conserved quantities, all gauge degrees of freedom have been eliminated in this form. The most relevant quantities of the solution, such as its energy, can be expressed through certain holomorphic integrals on the curve. This allows for a classification of finite gap solutions analogous to the general solution of strings in flat space. The role of fermions in the context of the algebraic curve is clarified. Finally, we derive a set of integral equations which reformulates the algebraic curve as a Riemann-Hilbert problem. They agree with the planar, one-loop N=4 supersymmetric gauge theory proving the complete agreement of spectra in this approximation.

  • 5. Beisert, Niklas
    et al.
    Tseytlin, A.A.
    Zarembo, Konstantin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Matching quantum strings to quantum spins: one-loop vs. finite-size corrections2005In: Nuclear Physics B, Vol. 715, p. 190-210Article in journal (Refereed)
    Abstract [en]

    We compare quantum corrections to semiclassical spinning strings in AdS(5)xS(5) to one-loop anomalous dimensions in N=4 supersymmetric gauge theory. The latter are computed using the reduced (Landau-Lifshitz) sigma model and with the help of the Bethe ansatz. The results of all three approaches are in remarkable agreement with each other. As a byproduct we establish the relationship between linear instabilities in the Landau-Lifshitz model and analyticity properties of the Bethe ansatz.

  • 6.
    Bredthauer, Andreas
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Lindström, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Persson, Jonas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    First-order supersymmetric sigma models and target space geometry2006In: Journal of High Energy Physics, Vol. 0601, p. 144-Article in journal (Refereed)
    Abstract [en]

    We study the conditions under which N=(1,1) generalized sigma models support an extension to N=(2,2). The enhanced supersymmetry is related to the target space complex geometry. Concentrating on a simple situation, related to Poisson sigma models, we develop a language that may help us analyze more complicated models in the future. In particular, we uncover a geometrical framework which contains generalized complex geometry as a special case.

  • 7.
    Carlson, Karin
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Mathematics and Computer Science, Department of Mathematics, Mathematics I -V.
    Kiselman, Christer
    Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Mathematics and Computer Science, Department of Mathematics, Mathematics I -V.
    Danielsson, Ulf
    Department of Theoretical Physics. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Mathematics and Computer Science, Department of Mathematics, Mathematics I -V.
    Halldin, Sven
    Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Mathematics and Computer Science, Department of Mathematics, Mathematics I -V.
    Mattsson, Amalia
    Language policy for a bilingual faculty2005In: Bi- and multilingual universities, Helsinki, Finland, Sept 1-3, 2005, 2005Conference paper (Refereed)
    Abstract [en]

    The Faculty of Science and Technology of Uppsala University is for all practical purposes a bilingual institution, using both Swedish and English in education and research. Extensive use of English in teaching, and also in intrauniversity communication, permits recruitment of nonSwedishspeaking students, researchers and professors, and also prepares our students for

    international careers. However, the introduction of English has been somewhat haphazard, not taking into account possible negative effects on communication in Swedish, nor on students'

    learning.

    In order to improve students' and professors' language skills, and achieve a good balance between Swedish and English, the faculty board appointed a language committee in 2003 whose task was to propose a language policy for the faculty. A first part, stating as a main goal that all communication from and within the faculty should have the highest quality possible, has been adopted by the board. A second part including language planning with respect to status, corpus, and acquisition for both Swedish and English to accomplish this goal was sent to the board of the faculty in May, 2005. Implementation of this policy will affect all faculty activities, especially education. Suggested

    annual reports on language status will raise our present minimal knowledge about possible domain losses and allow for relevant countermeasures.

  • 8.
    Chialva, Diego
    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.
    Johansson, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    Larfors, Magdalena
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Vonk, Marcel
    IHES.
    Deforming, revolving and resolving: New paths in the string theory landscape2008In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 02, article id 016Article in journal (Refereed)
    Abstract [en]

    In this paper we investigate the properties of series of vacua in the string theory landscape. In particular, we study minima to the flux potential in type IIB compactifications on the mirror quintic. Using geometric transitions, we embed its one-dimensional complex structure moduli space in that of another Calabi-Yau with h1,1 = 86 and h2,1 = 2. We then show how to construct infinite series of continuously connected minima to the mirror quintic potential by moving into this larger moduli space, applying its monodromies, and moving back. We provide an example of such series, and discuss their implications for the string theory landscape

  • 9.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Theoretical Physics.
    1905 - Einsteins fantastiska år2005In: Uppsala Nya Tidning, Vol. 2005, no 2005-02-27Article in journal (Other (popular scientific, debate etc.))
  • 10.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Det yppersta om universum i ett nötskal2002In: Dagens forskning, Vol. 2002, no 2Article in journal (Other (popular scientific, debate etc.))
  • 11.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    En visionär fyller 100 år2004In: Populär Astronomi, Vol. 2004, no 2Article in journal (Other (popular scientific, debate etc.))
  • 12.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Högskoleverket har ansvar för understimulans2002In: Dagens Nyheter, no 2002-09-08Article in journal (Other (popular scientific, debate etc.))
  • 13.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Inflation as a probe of new physics2006In: Journal of Cosmology and Astroparticle Physics, Vol. 03, no 014Article in journal (Refereed)
  • 14.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Kvantmekanikens absoluta slump2001In: Forskning och framsteg, Vol. 2001, no 3Article in journal (Other (popular scientific, debate etc.))
  • 15.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Lectures on string theory and cosmology2005In: Classical and Quantum Gravity, Vol. 22, p. S1-S40Article in journal (Refereed)
    Abstract [en]

    In these lectures I review recent attempts to apply string theory to cosmology, including string cosmology and various models of brane cosmology. In addition, the review includes an introduction to inflation as well as a discussion of transplanckian signatures. I also provide a critical discussion of the possible role of holography. The material is based on lectures given in January 2004 at the RTN String School in Barcelona, but also contain some additional material.

  • 16.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Något om strängteori2005In: Hjärnstorm, Vol. 85/86Article in journal (Other (popular scientific, debate etc.))
  • 17.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Till strängteorins försvar2004In: Forskning och framsteg, Vol. 2004, no 8Article in journal (Other (popular scientific, debate etc.))
  • 18.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Tomheten rymmer mer än man kan ana2001In: Svenska Dagbladet, no 2001-06-05Article in journal (Other (popular scientific, debate etc.))
  • 19.
    Danielsson, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Transplanckian energy production and slow roll inflation2005In: Physical Review D, Vol. 71, p. 023516-Article in journal (Refereed)
    Abstract [en]

    In this paper we investigate how the energy density due to a non-standard choice of initial vacuum affects the expansion of the universe during inflation. To do this we introduce source terms in the Friedmann equations making sure that we respect the relation between gravity and thermodynamics. We find that the energy production automatically implies a slow rolling cosmological constant. Hence we also conclude that there is no well defined value for the cosmological constant in the presence of sources. We speculate that a non-standard vacuum can provide slow roll inflation on its own.

  • 20.
    Danielsson, Ulf
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Johansson, Niklas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Larfors, Magdalena
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Olsson, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Vonk, Marcel
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    4D black holes and holomorphic factorization of the 0A matrix model2005In: Journal of High Energy Physics, Vol. 0510, p. 046-Article in journal (Refereed)
    Abstract [en]

    n this letter, we relate the free energy of the 0A matrix model to the sum of topological and anti-topological string amplitudes. For arbitrary integer multiples of the matrix model self-dual radius we describe the geometry on which the corresponding topological string propagates. This geometry is not the one that follows from the usual ground ring analysis, but in a sense its "holomorphic square root". Mixing of terms for different genus in the matrix model free energy yields one-loop terms compatible with type II strings on compact Calabi-Yau target spaces. As an application, we give an explicit example of how to relate the 0A matrix model free energy to that of a four-dimensional black hole in type IIB theory, compactified on a compact Calabi-Yau. Variables, Legendre transforms, and large classical terms on both sides match perfectly.

  • 21. Hong, Soon-Tae
    et al.
    Niemi, Antti
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    BRST extension of the Faddeev model2005In: Physical Review D, Vol. 72, p. 127701-Article in journal (Refereed)
    Abstract [en]

    The Faddeev model is a second class constrained system. Here we construct its nilpotent BRST operator and derive the ensuing manifestly BRST invariant Lagrangian. Our construction employs the structure of Stuckelberg fields in a nontrivial fashion.

  • 22. Howe, Paul
    et al.
    Lindström, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Stojevic, V.
    Special holonomy sigma models with boundaries2006In: Journal of High Energy Physics, Vol. 0601, p. 159-Article in journal (Other (popular scientific, debate etc.))
    Abstract [en]

    A study of (1,1) supersymmetric two-dimensional non-linear sigma models with boundary on special holonomy target spaces is presented. In particular, the consistency of the boundary conditions under the various symmetries is studied. Models both with and without torsion are discussed.

  • 23. Howe, Paul
    et al.
    Lindström, Ulf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Wulff, Linus
    Superstrings with boundary fermions2005In: Journal of High Energy Physics, Vol. 0508, p. 041-Article in journal (Refereed)
    Abstract [en]

    The Green-Schwarz action for an open superstring with additional boundary fermions, representing Chan-Paton factors, is studied at the classical level. The boundary geometry is described by a bundle, with fermionic fibres, over the super worldvolume of a D-brane together with a map from the total space into the type II target superspace. This geometry is constrained by the requirement of kappa-symmetry on the boundary together with the use of the equations of motion for the fermions. There are two constraints which are formally similar to those that arise in the abelian case but which differ because of the dependence on the additional coordinates. The model, when quantised, would be a candidate for a fully kappa-symmetric theory of a stack of coincident D-branes including a non-abelian Born-Infeld sector. The example of the D9-brane in a flat background is studied. The constraints on the non-abelian field strength are shown to be in agreement with those derived from the pure spinor approach to the superstring. A covariant formalism is developed and the problem of quantisation is discussed.

  • 24. Kazakov, V. A.
    et al.
    Marshakov, A.
    Minahan, Joseph A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    Zarembo, Konstantin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    Classical/quantum integrability in AdS/CFT2004In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 05, p. 024-Article in journal (Refereed)
    Abstract [en]

    We discuss the AdS/CFT duality from the perspective of integrable systems and establish a direct relationship between the dimension of single trace local operators composed of two types of scalar fields in = 4 super Yang-Mills and the energy of their dual semiclassical string states in AdS5 × S5. The anomalous dimensions can be computed using a set of Bethe equations, which for ``long'' operators reduces to a Riemann-Hilbert problem. We develop a unified approach to the long wavelength Bethe equations, the classical ferromagnet and the classical string solutions in the SU(2) sector and present a general solution, governed by complex curves endowed with meromorphic differentials with integer periods. Using this solution we compute the anomalous dimensions of these long operators up to two loops and demonstrate that they agree with string-theory predictions.

  • 25.
    Kiselman, Christer
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematics I -V. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics. Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology.
    Halldin, Sven
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematics I -V. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics. Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology.
    Danielsson, Ulf
    Department of Theoretical Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematics I -V. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics. Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology.
    Carlson, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematics I -V. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics. Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology.
    Mattsson, Amalia
    Rutberg, Martin
    "Svenska språket dör ut på landets universitet": DN - Debatt2005In: Dagens Nyheter, no 2005-06-17Article in journal (Other (popular scientific, debate etc.))
  • 26.
    Larsen, Kasper
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    Boels, Rutger
    Niels Bohr Institute.
    Obers, Niels A.
    Niels Bohr Institute.
    Vonk, Marcel
    University of the Witwatersrand.
    MHV, CSW and BCFW: field theory structures in string theory amplitudes2008In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 11, no 015, p. 1-59Article in journal (Refereed)
    Abstract [en]

    Motivated by recent progress in calculating field theory amplitudes, we study applications of the basic ideas in these developments to the calculation of amplitudes in string theory. We consider in particular both non-Abelian and Abelian open superstring disk amplitudes in a flat space background, focusing mainly on the four-dimensional case. The basic field theory ideas under consideration split into three separate categories. In the first, we argue that the calculation of α'-corrections to MHV open string disk amplitudes reduces to the determination of certain classes of polynomials. This line of reasoning is then used to determine the α'3-correction to the MHV amplitude for all multiplicities. A second line of attack concerns the existence of an analog of CSW rules derived from the Abelian Dirac-Born-Infeld action in four dimensions. We show explicitly that the CSW-like perturbation series of this action is surprisingly trivial: only helicity conserving amplitudes are non-zero. Last but not least, we initiate the study of BCFW on-shell recursion relations in string theory. These should appear very naturally as the UV properties of the string theory are excellent. We show that all open four-point string amplitudes in a flat background at the disk level obey BCFW recursion relations. Based on the naturalness of the proof and some explicit results for the five-point gluon amplitude, it is expected that this pattern persists for all higher point amplitudes and for the closed string.

  • 27.
    Lindström, Ulf
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Minasian, Ruben
    Tomasiello, Alessandro
    Zabzine, Maxim
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Generalized complex manifolds and supersymmetry2005In: Communications in Mathematical Physics, Vol. 257, p. 235-256Article in journal (Refereed)
    Abstract [en]

    We find a worldsheet realization of generalized complex geometry, a notion introduced recently by Hitchin which interpolates between complex and symplectic manifolds. The two-dimensional model we construct is a supersymmetric relative of the Poisson sigma model used in context of deformation quantization.

  • 28.
    Lindström, Ulf
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Rocek, Martin
    von Unge, Rikard
    Ricci-flat supertwistor spaces2006In: Journal of High Energy Physics, Vol. 0601, no 163Article in journal (Refereed)
    Abstract [en]

    We show that supertwistor spaces constructed as a Kahler quotient of a hyperkahler cone (HKC) with equal numbers of bosonic and fermionic coordinates are Ricci-flat, and hence, Calabi-Yau. We study deformations of the supertwistor space induced from deformations of the HKC. We also discuss general infinitesimal deformations that preserve Ricci-flatness.

  • 29.
    Lindström, Ulf
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Rocek, Martin
    von Unge, Rikard
    Zabzine, Maxim
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Generalized Kahler geometry and manifest N=(2,2) supersymmetric nonlinear sigma-models2005In: Journal of High Energy Physics, Vol. 0507, p. 067-Article in journal (Refereed)
    Abstract [en]

    Generalized complex geometry is a new mathematical framework that is useful for describing the target space of N=(2,2) nonlinear sigma-models. The most direct relation is obtained at the N=(1,1) level when the sigma model is formulated with an additional auxiliary spinorial field. We revive a formulation in terms of N=(2,2) semi-(anti)chiral multiplets where such auxiliary fields are naturally present. The underlying generalized complex structures are shown to commute (unlike the corresponding ordinary complex structures) and describe a Generalized Kahler geometry. The metric, B-field and generalized complex structures are all determined in terms of a potential K.

  • 30.
    Lindström, Ulf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    Rocek, Martin
    von Unge, Rikard
    Zabzine, Maxim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    Linearizing Generalized Kahler Geometry2007In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 4, p. 061-Article in journal (Refereed)
    Abstract [en]

    The geometry of the target space of an N = (2, 2) supersymmetry sigma-model carries a generalized Kähler structure. There always exists a real function, the generalized Kähler potential K, that encodes all the relevant local differential geometry data: the metric, the B-field, etc. Generically this data is given by nonlinear functions of the second derivatives of K. We show that, at least locally, the nonlinearity on any generalized Kähler manifold can be explained as arising from a quotient of a space without this nonlinearity.

  • 31.
    Lundgren, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
    Darnerud, Per Ola
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Molin, Ylva
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
    Lilienthal, Hellmuth
    Livsmedelsverket.
    Blomberg, Jonas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Virology.
    Ilbäck, Nils-Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
    Viral infection and PBDE exposure interact on CYP gene expression and enzyme activities in the mouse liver2007In: Toxicology, ISSN 0300-483X, E-ISSN 1879-3185, Vol. 242, no 1-3, p. 100-108Article in journal (Refereed)
    Abstract [en]

    In the present study coxsackievirus B3 (CVB3) adapted to Balb/c mice was used to examine whether infection affects xenobiotic-metabolising CYP1A1 and CYP2B gene expression (measured by RT-PCR) and the corresponding enzyme activities of ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-depentylase (PROD), as observed on day 3 of infection. To study the simultaneous effects of xenobiotic exposure, mice were administered the polybrominated diphenyl ether (PBDE) compounds BDE-99 (single congener) and Bromkal 70-5 DE (commercial mixture). Serum thyroxine levels were also measured. High numbers of CVB3 were found in the livers of infected mice but no significant effects of PBDE on virus replication were observed. In infected mice gene expression and CYP activities were decreased in comparison with non-infected mice, especially for CYP2B. PBDE exposure in the non-infected mice was characterised by an increase in both CYP2B and PROD levels/activities, whereas CYP1A levels increased and EROD activity decreased. In general, PBDE exposure in the infected mice did not increase EROD and PROD activities to the same extent as in the non-infected exposed mice. Infected mice exposed to BDE-99 showed significantly higher CYP2B and PROD levels than both the infected non-exposed and Bromkal-exposed groups. T(4) levels were greatly decreased by infection and a tendency of reduced T(4) levels after PBDE exposure could be observed in non-infected mice. In conclusion, infection reduced the detoxifying capacity of the liver and the serum T(4) levels. PBDE exposure can modify these effects. Notably, in the infected mice differences between BDE-99 and Bromkal were observed on CYP2B gene expression and PROD activity.

  • 32. Mattsson, Amalia
    et al.
    Kiselman, Christer
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematics I -V. Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics.
    Carlson, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematics I -V. Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics.
    Rutberg, Martin
    Halldin, Sven
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematics I -V. Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics.
    Danielsson, Ulf
    Department of Theoretical Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematics I -V. Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Earth Sciences, Department of Earth Sciences, Air and Water Science. Physics, Department of Physics and Materials Science, Theoretical Physics.
    Utbildningens internationalisering och demokratin2005In: Quartilen, Vol. 20, no 3, p. 15-16Article in journal (Other (popular scientific, debate etc.))
  • 33.
    Minahan, Joseph A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    The SU(2) sector in AdS/CFT2005In: RTN Workshop On The Quantum Structure Of Space-Time And The Geometric Nature Of Fundamental Interactions And EXT Workshop On Fundamental Interactions And The Structure Of Spacetime, 2005Conference paper (Refereed)
    Abstract [en]

    In the large N limit of N=4 Super Yang-Mills, the mixing under dilatations of the SU(2) sector, single trace operators composed of L complex scalar fields of two types, is closed to all orders in perturbation theory. By relying on the AdS/CFT correspondence, and by examining the currents for semiclassical strings, we present evidence which implies that there are small mixings that contradict the closure of the SU(2) sector in the strong coupling limit. These mixings first appear to second order in the \lambda/L^2 expansion.

  • 34.
    Minahan, Joseph A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics, Theoretical Physics.
    Tirzu, A.
    Tseytlin, A. A.
    1/J corrections to semiclassical AdS/CFT states from quantum Landau-Lifshitz model2006In: Nuclear Physics B, Vol. 735, p. 127-171Article in journal (Refereed)
    Abstract [en]

    One way to relate semiclassical string states and dual gauge theory states is to show the equivalence between their low-energy effective 2d actions. The gauge theory effective action, which is represented by an effective Landau-Lifshitz (LL) model, was previously found to match with the string theory world-sheet action up to the first two orders in the effective parameter $\tilde{\lambda} ={\lambda / J^2}$, where $\lambda$ is the `t Hooft coupling and $J$ is the total $R$-charge. Here we address the question if quantizing the effective LL action reproduces the subleading 1/J corrections to the spin chain energies as well as the quantum corrections to the string energies. We demonstrate that this is indeed the case provided one chooses an appropriate regularization of the effective LL theory. Expanding near the BPS vacuum, we show that the quantum LL action gives the same 1/J corrections to energies of BMN states as found previously on the gauge theory and string theory sides. We also compute the subleading $1/J^2$ corrections and show that these too match with corrections computed from the Bethe ansatz. We also compare the results from the LL action with a more direct computation from the spin chain. We repeat the same computation for the $\beta$-deformed LL action and find that the quantum LL result is again equal to the 1/J correction computed from the $\beta$-deformed Bethe ansatz equations. We also quantize the LL action near the rotating circular and folded string solutions, generalizing the known gauge/string results for 1/J corrections to the classical energies. We emphasize the simplicity of this effective field theory approach as compared to the full quantum string computations.

  • 35.
    Niemi, Antti
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Could Spin-Charge Separation be the Source of Confinement?2006In: AIP Conference Proceedings, Vol. 806, p. 114-123Article in journal (Other (popular scientific, debate etc.))
  • 36.
    Niemi, Antti
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    The Exotic Statistics of Leapfrogging Smoke Rings2005In: Physical Review Letters, Vol. 94, p. 124502-Article in journal (Refereed)
    Abstract [en]

    The leapfrogging motion of smoke rings is a three dimensional version of the motion that in two dimensions leads to exotic exchange statistics. The statistical phase factor can be computed using the hydrodynamical Euler equation, which is a universal law for describing the properties of a large class of fluids. This suggests that three dimensional exotic exchange statistics is a common property of closed vortex loops in a variety of quantum liquids and gases, from helium superfluids to Bose-Einstein condensed alkali gases, metallic hydrogen in its liquid phases and maybe even nuclear matter in extreme conditions.

  • 37.
    Niemi, Antti
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Marshakov, Andrei
    Yang-Mills, Complex Structures and Chern's Last Theorem2005In: Modern Physics Letters A, Vol. 20, p. 2583-2600Article in journal (Refereed)
    Abstract [en]

    Recently Shiing-Shen Chern suggested that the six dimensional sphere $\mathbb{S}^6$ has no complex structure. Here we explore the relations between his arguments and Yang-Mills theories. In particular, we propose that Chern's approach is widely applicable to investigate connections between the geometry of manifolds and the structure of gauge theories. We also discuss several examples of manifolds, both with and without a complex structure.

  • 38.
    Niemi, Antti
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Walet, Niels
    Splitting the gluon?2005In: Physical Review D, Vol. 72, p. 054007-Article in journal (Other (popular scientific, debate etc.))
    Abstract [en]

    In the strongly correlated environment of high-temperature cuprate superconductors, the spin and charge degrees of freedom of an electron seem to separate from each other. A similar phenomenon may be present in the strong coupling phase of Yang-Mills theories, where a separation between the color charge and the spin of a gluon could play a role in a mass gap formation. Here we study the phase structure of a decomposed SU(2) Yang-Mills theory in a mean field approximation, by inspecting quantum fluctuations in the condensate which is formed by the color charge component of the gluon field. Our results suggest that the decomposed theory has an involved phase structure. In particular, there appears to be a phase which is quite reminiscent of the superconducting phase in cuprates. We also find evidence that this phase is separated from the asymptotically free theory by an intermediate pseudogap phase.

  • 39.
    Nygren, Else
    Uppsala University, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Faculty of Social Sciences, Department of Information Science. Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Theoretical Physics. Människa-datorinteraktion.
    Resonances in 2D CA of Class IV2006In: NKS2006 WolframScienceConference Washington June 15 - 18 2006, 2006Conference paper (Refereed)
    Abstract [en]

    In a famous paper of 1984, Packard and Wolfram describe the properties of two-dimensional cellular automata, 2D CA. The authors describe the behavior of some 2D CA of class IV. This class of CA shows interesting behavior with a mixture of chaotic, static, and periodic ingredients. One famous such rule is the Game of Life, which has been extensively described in the literature.

    I have investigated a family of 2D CAs that all exhibits the behavior of class IV. In particular I have investigated what happens when such a CA evolves from small seeds in restricted spaces. It was found that for most seeds a growing structure evolves, but as soon as this encounters the border of the CA universe, the symmetry is broken and the CA settles in a state consisting of distributed static or periodic small structures. However, there seems to exist a critical size where the growth will result in a dynamical resonance. Such a resonance consists of a single periodically changing structure often with a high degree of symmetry, with some static cells and others dynamically changing. We call this a resonance since it only appears in certain combinations of seed and universe size. We can assess a measure of the “energy” of such a resonance in terms of how many cells that change on average per CA time step. In the evolution of such a CA from the initial seed, several temporal but unstable resonances are formed. We can often see distinct phases of successive resonances of lower and lower energy. Each time a temporal resonance emits gliders (photons), its energy is reduced until it finally settles down into a resonance pattern of the lowest possible energy.

    There is a large number of possible initial seeds of size 2 x 2 cells. Many of these are redundant, and we can find that there is actually only a limited set of types of such seeds that gives characteristically different resonances. Type 1 shows a resonance that is symmetrical with respect to rotation as well as mirror reflection in the x- and y-planes. Type 2 is likewise symmetrical but has a hole in the middle. Type 3 is also symmetrical except for a small area around the center that is only diagonally symmetric. Type 4 is diagonally symmetrical but not rotationally or in terms of mirror reflection. It also has a center area that shows a different symmetry. Type 5 is interesting, it has the properties of type 2 but has a small particle in the center hole that is slowly rotating around the inside. You could say that this resonance possesses some kind of momentum. Type 6 shows symmetrical properties except for the center area where there is a periodic right to left oscillatory movement.

    The notion of having a confined space for the CA to evolve seems very constraining. There seems to be a need for some “resistance” in order to develop the resonance. What if instead of encountering a border the growing CA would encounter another growing CA? It turns out that this indeed works to produce resonances. Some CA seeds make up nice grids together in this way. Others interfere destructively with each other no matter the separation between the seeds. But with this notion of seeds making up constrained spaces for each other it is possible to build grids of a whole variety. Most specificially the kind of grids normally used in material sciences.

    Now, having the possibility to construct grids, we can study what happens when we emit “light” in the forms of rays of photons against such grids. We can see that depending on the phase relation between the photon and the resonances in the grid the photon is either absorbed, scattered with a change of wavelength or reflected back from the material surface.

    In summary, resonances in 2D CA of Class IV seem to exhibit many interesting “physics-like” behavior. We can see discrete energy states, excitation, emission of particles, reflection, asorbtion, and scattering phenomena. We can also see that a photon can be scattered by “virtual particles” interpreted as temporal resonances. We can also see some quantum-like phenomena as the particular outcome of an interaction that seems random as seen from a distance. The resonances also show an ability to self-synchronize. If they start out being out of phase, they spontaneously synchronize with each other, the result being a combined resonance completely phase-tuned.

  • 40. Schäfer-Nameki, Sakura
    et al.
    Zamaklar, Marija
    Zarembo, Konstantin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Quantum corrections to spinning strings in AdS(5)xS(5) and Bethe ansatz: a comparative study2005In: Journal of High Energy Physics, Vol. 0509, p. 051-Article in journal (Other (popular scientific, debate etc.))
    Abstract [en]

    We analyze quantum corrections to rigid spinning strings in AdS(5)xS(5). The one-loop worldsheet quantum correction to the string energy is compared to the finite-size correction from the quantum string Bethe ansatz. Expanding the summands of the string theory energy shift in the parameter \lambda/J^2 and subsequently resumming them yields a divergent result. However, upon zeta-function regularization this result agrees with the Bethe ansatz at the first three orders. We also perform an analogous computation in the limit of large winding number, which results in a disagreement with the string Bethe ansatz prediction. A similar mismatch is observed numerically. We comment on the possible origin of this discrepancy.

  • 41.
    Zarembo, Konstantin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Antiferromagnetic Operators in N=4 Supersymmetric Yang-Mills Theory2006In: Physics Letters B, Vol. 634, p. 552-556Article in journal (Refereed)
    Abstract [en]

    The spectrum of operators in the su(2) sector of N=4 SYM is bounded because the number of operators is finite. According to the AdS/CFT correspondence, the string spectrum in this sector should be also bounded. In this paper the upper bound on the scaling dimension is calculated in the limit of the large R-charge using Bethe ansatz.

  • 42.
    Zarembo, Konstantin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Theoretical Physics. Department of Physics and Materials Science, Theoretical Physics.
    Semiclassical Bethe Ansatz and AdS/CFT2005In: Fortschritte der Physik, Vol. 53, p. 647-657Article in journal (Refereed)
    Abstract [en]

    The Bethe ansatz can be used to compute anomalous dimensions in N=4 SYM theory. The classical solutions of the sigma-model on AdS(5)xS(5) can also be parameterized by an integral equation of Bethe type. In this note the relationship between the two Bethe ansaetze is reviewed following hep-th/0402207.

1 - 42 of 42
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