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Publications (10 of 47) Show all publications
Ekstedt, A., Enberg, R., Ingelman, G., Löfgren, J. & Mandal, T. (2018). Minimal anomalous U(1) theories and collider phenomenology. Journal of High Energy Physics (JHEP), 1802, 152
Open this publication in new window or tab >>Minimal anomalous U(1) theories and collider phenomenology
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2018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 1802, p. 152-Article in journal (Refereed) Published
Abstract [en]

We study the collider phenomenology of a neutral gauge boson Z′ arising in minimal but anomalous U(1) extensions of the Standard Model (SM). To retain gauge invariance of physical observables, we consider cancellation of gauge anomalies through the Green-Schwarz mechanism. We categorize a wide class of U(1) extensions in terms of the new U(1) charges of the left-handed quarks and leptons and the Higgs doublet. We derive constraints on some benchmark models using electroweak precision constraints and the latest 13 TeV LHC dilepton and dijet resonance search data. We calculate the decay rates of the exotic and rare one-loop Z′ decays to ZZ and Z-photon modes, which are the unique signatures of our framework. If observed, these decays could hint at anomaly cancellation through the Green-Schwarz mechanism. We also discuss the possible observation of such signatures at the LHC and at future ILC colliders.

National Category
Subatomic Physics
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-336639 (URN)10.1007/JHEP02(2018)152 (DOI)000426358100007 ()
Funder
Carl Tryggers foundation , CTS-14:206Swedish Research Council, 621-2011-5107
Available from: 2017-12-15 Created: 2017-12-15 Last updated: 2018-04-26Bibliographically approved
Enberg, R., Klemm, W., Moretti, S. & Munir, S. (2017). Electroweak production of light scalar-pseudoscalar pairs from extended Higgs sectors. Physics Letters B, 764, 121-125
Open this publication in new window or tab >>Electroweak production of light scalar-pseudoscalar pairs from extended Higgs sectors
2017 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 764, p. 121-125Article in journal (Refereed) Published
Abstract [en]

In models with extended Higgs sectors, it is possible that the Higgs boson discovered at the LHC is not the lightest one. We show that in a realistic model (the Type I 2-Higgs Doublet Model), when the sum of the masses of a light scalar and a pseudoscalar (h and A) is smaller than the Z boson mass, the Electroweak (EW) production of an hA pair, which is generally neglected, can dominate over QCD production by orders of magnitude. This is because in the gg-initiated process, hA production via a resonant Z in the s-channel is prohibited according to the Landau-Yang theorem, which is not the case for the qq-initiated process. We explore the parameter space of the model to highlight regions giving such hA solutions while being consistent with all constraints from collider searches, b-physics and EW precision data. We also single out a few benchmark points to discuss their salient features, including the hA search channels that can be exploited at Run II of the LHC.

Keywords
Higgs bosons, beyond the Standard Model, LHC
National Category
Subatomic Physics
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-292869 (URN)10.1016/j.physletb.2016.11.012 (DOI)000390127100015 ()
Funder
Swedish Research Council, 621-2011-5107EU, Horizon 2020, H2020-MSCA-RISE-2014 No. 645722
Available from: 2016-05-10 Created: 2016-05-10 Last updated: 2017-11-30Bibliographically approved
Danielsson, U., Enberg, R., Ingelman, G. & Mandal, T. (2017). Heavy photophilic scalar at the LHC from a varying electromagnetic coupling. Nuclear Physics B, 919, 569-582
Open this publication in new window or tab >>Heavy photophilic scalar at the LHC from a varying electromagnetic coupling
2017 (English)In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 919, p. 569-582Article in journal (Refereed) Published
Abstract [en]

We investigate the phenomenology of a heavy scalar ϕ of the type involved in Bekenstein's framework for varying electromagnetic coupling theories, with the difference that the scalar in our model has a large mass. The model has only two free parameters, the mass Mϕ of the scalar and the scale Λ of new physics. The scalar is dominantly produced through photon-photon fusion at the LHC and leads to a diphoton final state. It can also be produced by quark-antiquark fusion in association with a photon or a fermion pair. Its dominating decay is to diphotons, but it also has a large three-body branching to a fermion pair and a photon, which can provide an interesting search channel with a dilepton-photon resonance. We derive exclusion limits on the Mϕ−Λplane from the latest 13 TeV LHC diphoton resonance search data. For a benchmark mass of Mϕ∼1 TeV, we find a lower limit on Λ of 18 TeV. We discuss the more complex possibility of varying couplings in the full electroweak theory and comment on the possibility that the new physics is related to extra dimensions or string theory.

National Category
Subatomic Physics
Research subject
Theoretical Physics; Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-273772 (URN)10.1016/j.nuclphysb.2017.04.003 (DOI)000402344700026 ()
Funder
Swedish Research Council, 621-2011-5107Swedish Research Council, 2015-04814Carl Tryggers foundation , CTS- 14:206
Available from: 2016-01-18 Created: 2016-01-18 Last updated: 2017-08-10Bibliographically approved
Arhrib, A., Benbrik, R., Enberg, R., Klemm, W., Moretti, S. & Munir, S. (2017). Identifying a light charged Higgs boson at the LHC Run II. Physics Letters B, 774, 591-598
Open this publication in new window or tab >>Identifying a light charged Higgs boson at the LHC Run II
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2017 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 774, p. 591-598Article in journal (Refereed) Published
Abstract [en]

We analyse the phenomenological implications of a light Higgs boson, h, within the CP-conserving 2-Higgs Doublet Model (2HDM) Type-I, for the detection prospects of the charged H± state at Run II of the Large Hadron Collider (LHC), assuming s√=13 TeV as energy and O(100 fb−1) as luminosity. When sufficiently light, this h state can open up the bosonic decay channel H±→W±(∗)h, which may have a branching ratio significantly exceeding those of the H±→τν and H±→cs channels. We perform a broad scan of the 2HDM Type-I parameter space, assuming the heavier of the two CP-even Higgs bosons, H, to be the observed SM-like state with a mass near 125 GeV. Through these scans we highlight regions in which mH±<mt+mb that are still consistent with the most recent limits from experimental searches. We find in these regions that, when the H±→W±(∗)h decay mode is the dominant one, the h can be highly fermiophobic, with a considerably large decay rate in the γγ channel. This can result in the total cross section of the σ(pp→H±h→W±(∗)+4γ) process reaching up to O(100 fb). We therefore investigate the possibility of observing this spectacular signal at the LHC Run II.

Keywords
Higgs, LHC, charged Higgs
National Category
Subatomic Physics
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-323610 (URN)10.1016/j.physletb.2017.10.006 (DOI)000414973200077 ()
Available from: 2017-06-08 Created: 2017-06-08 Last updated: 2018-03-09Bibliographically approved
Edsjö, J., Elevant, J., Enberg, R. & Niblaeus, C. (2017). Neutrinos from cosmic ray interactions in the Sun. Journal of Cosmology and Astroparticle Physics (06), Article ID 033.
Open this publication in new window or tab >>Neutrinos from cosmic ray interactions in the Sun
2017 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 06, article id 033Article in journal (Refereed) Published
Abstract [en]

Cosmic rays hitting the solar atmosphere generate neutrinos that interact and oscillate in the Sun and oscillate on the way to Earth. These neutrinos could potentially be detected with neutrino telescopes and will be a background for searches for neutrinos from dark matter annihilation in the Sun. We calculate the flux of neutrinos from these cosmic ray interactions in the Sun and also investigate the interactions near a detector on Earth that give rise to muons. We compare this background with both regular Earth-atmospheric neutrinos and signals from dark matter annihilation in the Sun. Our calculation is performed with an event-based Monte Carlo approach that should be suitable as a simulation tool for experimental collaborations. Our program package is released publicly along with this paper.

Keywords
Neutrinos, cosmic rays, sun, WIMP, neutrino oscillations
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-319951 (URN)10.1088/1475-7516/2017/06/033 (DOI)000408310600003 ()
Available from: 2017-04-11 Created: 2017-04-11 Last updated: 2017-12-19Bibliographically approved
Jeong, Y. S., Bhattacharya, A., Enberg, R., Kim, C. S., Reno, M. H., Sarcevic, I. & Stasto, A. (2017). Prompt atmospheric neutrino flux from the various QCD models. In: Yoo, I K (Ed.), XLVI International Symposium On Multiparticle Dynamics (ISMD 2016): . Paper presented at 46th International Symposium on Multiparticle Dynamics (ISMD), AUG 29-SEP 02, 2016, SOUTH KOREA. , Article ID UNSP 07002.
Open this publication in new window or tab >>Prompt atmospheric neutrino flux from the various QCD models
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2017 (English)In: XLVI International Symposium On Multiparticle Dynamics (ISMD 2016) / [ed] Yoo, I K, 2017, article id UNSP 07002Conference paper, Published paper (Refereed)
Abstract [en]

We evaluate the prompt atmospheric neutrino flux using the different QCD models for heavy quark production including the b quark contribution. We include the nuclear correction and find it reduces the fluxes by 10% - 50% according to the models. Our heavy quark results are compared with experimental data from RHIC, LHC and LHCb.

Series
EPJ Web of Conferences, ISSN 2100-014X ; 141
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-335839 (URN)10.1051/epjconf/201714107002 (DOI)000404462600046 ()
Conference
46th International Symposium on Multiparticle Dynamics (ISMD), AUG 29-SEP 02, 2016, SOUTH KOREA
Available from: 2017-12-15 Created: 2017-12-15 Last updated: 2017-12-15Bibliographically approved
Jeong, Y. S., Bhattacharya, A., Enberg, R., Kim, C. S., Reno, M. H., Sarcevic, I. & Stasto, A. (2017). Prompt atmospheric neutrino flux in perturbative QCD and its theoretical uncertainties. In: XXVII International Conference on Neutrino Physics and Astrophysics (Neutrino2016): . Paper presented at 27th International Conference on Neutrino Physics and Astrophysics (Neutrino), JUL 04-09, 2016, Royal Geog Soc, London, ENGLAND. Institute of Physics Publishing (IOPP), Article ID 012117.
Open this publication in new window or tab >>Prompt atmospheric neutrino flux in perturbative QCD and its theoretical uncertainties
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2017 (English)In: XXVII International Conference on Neutrino Physics and Astrophysics (Neutrino2016), Institute of Physics Publishing (IOPP), 2017, article id 012117Conference paper, Published paper (Refereed)
Abstract [en]

Using the most recent PDFs and the cosmic ray spectrum, we evaluate the charm/bottom induced prompt atmospheric muon neutrino fluxes including nuclear corrections. We investigate their impact in perturbative QCD and estimate the comprehensive uncertainties from other various factors. The prompt atmospheric tau neutrino fluxes are also presented.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2017
Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 888
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-351186 (URN)10.1088/1742-6596/888/1/012117 (DOI)000424332100117 ()
Conference
27th International Conference on Neutrino Physics and Astrophysics (Neutrino), JUL 04-09, 2016, Royal Geog Soc, London, ENGLAND
Funder
Swedish Research Council
Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2018-05-23Bibliographically approved
Ekstedt, A., Enberg, R., Ingelman, G., Löfgren, J. & Mandal, T. (2016). Constraining minimal anomaly free U(1) extensions of the Standard Model. Journal of High Energy Physics (JHEP), 1611, Article ID 071.
Open this publication in new window or tab >>Constraining minimal anomaly free U(1) extensions of the Standard Model
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2016 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 1611, article id 071Article in journal (Refereed) Published
Abstract [en]

We consider a class of minimal anomaly free U(1) extensions of the Standard Model with three generations of right-handed neutrinos and a complex scalar. Using electroweak precision constraints, new 13 TeV LHC data, and considering theoretical limitations such as perturbativity, we show that it is possible to constrain a wide class of models. By classifying these models with a single parameter, κ, we can put a model independent upper bound on the new U(1) gauge coupling gz. We find that the new dilepton data puts strong bounds on the parameters, especially in the mass region MZ′≲3 TeV.

Keywords
Beyond Standard Model, Gauge Symmetry
National Category
Subatomic Physics
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-301819 (URN)10.1007/JHEP11(2016)071 (DOI)000387691500010 ()
Funder
Carl Tryggers foundation , CTS-14:206Swedish Research Council, 621-2011-5107
Available from: 2016-08-25 Created: 2016-08-25 Last updated: 2017-11-28Bibliographically approved
Bhattacharya, A., Enberg, R., Jeong, Y. S., Kim, C. S., Reno, M. H., Sarcevic, I. & Stasto, A. (2016). Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects. Journal of High Energy Physics (JHEP), 11, Article ID 167.
Open this publication in new window or tab >>Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects
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2016 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 11, article id 167Article in journal (Refereed) Published
Abstract [en]

We evaluate the prompt atmospheric neutrino flux at high energies using three different frameworks for calculating the heavy quark production cross section in QCD: NLO perturbative QCD, kT factorization including low-x resummation, and the dipole model including parton saturation. We use QCD parameters, the value for the charm quark mass and the range for the factorization and renormalization scales that provide the best description of the total charm cross section measured at fixed target experiments, at RHIC and at LHC. Using these parameters we calculate differential cross sections for charm and bottom production and compare with the latest data on forward charm meson production from LHCb at 7 TeV and at 13 TeV, finding good agreement with the data. In addition, we investigate the role of nuclear shadowing by including nuclear parton distribution functions (PDF) for the target air nucleus using two different nuclear PDF schemes. Depending on the scheme used, we find the reduction of the flux due to nuclear effects varies from 10% to 35% at the highest energies. Finally, we compare our results with the IceCube limit on the prompt neutrino flux, which is already providing valuable information about some of the QCD models.

Keywords
Neutrino Physics, Perturbative QCD, Solar and Atmospheric Neutrinos
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-301817 (URN)10.1007/JHEP11(2016)167 (DOI)000389346400006 ()
Funder
Swedish Research Council, 621-2011-5107
Available from: 2016-08-25 Created: 2016-08-25 Last updated: 2017-11-28Bibliographically approved
Bhattacharya, A., Enberg, R., Reno, M. H. & Sarcevic, I. (2015). Charm decay in slow-jet supernovae as the origin of the IceCube ultra-high energy neutrino events. Journal of Cosmology and Astroparticle Physics, 6, Article ID 034.
Open this publication in new window or tab >>Charm decay in slow-jet supernovae as the origin of the IceCube ultra-high energy neutrino events
2015 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 6, article id 034Article in journal (Refereed) Published
Abstract [en]

We investigate whether the recent ultra-high energy (UHE) neutrino events detected at the IceCube neutrino observatory could come from the decay of charmed mesons produced within the mildly relativistic jets of supernova-like astrophysical sources. We demonstrate that the 5.7σ excess of neutrinos observed by IceCube in the energy range 30 TeV--2 PeV can be explained by a diffuse flux of neutrinos produced in such slow-jet supernovae, using the values of astrophysical and QCD parameters within the theoretical uncertainties associated with neutrino production from charmed meson decay in astrophysical sources. We discuss the theoretical uncertainties inherent in the evaluation of charm production in high energy hadronic collisions, as well as the astrophysical uncertainties associated with slow-jet supernova sources. The proton flux within the source, and therefore also the produced neutrino flux, is cut off at around a few PeV, when proton cooling processes become dominant over proton acceleration. This directly explains the sudden drop in event rates at energies above a few PeV. We incorporate the effect of energy dependence in the spectrum-weighted charm production cross-section and show that this has a very significant effect on the shape, magnitude and cut-off energies for the neutrino flux.

Keywords
Ultrahigh energy neutrinos, IceCube, charm quarks, supernova
National Category
Subatomic Physics
Research subject
Physics with specialization in Elementary Particle Physics
Identifiers
urn:nbn:se:uu:diva-229748 (URN)10.1088/1475-7516/2015/06/034 (DOI)000359215400035 ()
Funder
Swedish Research Council, 621-2011-5107
Available from: 2014-08-12 Created: 2014-08-12 Last updated: 2017-12-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0452-0671

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