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Araujo Filho, A. A., Zare, S., Porffrio, P. J., Kriz, J., & Hassanabadi, H. (2023). Thermodynamics and evaporation of a modified Schwarzschild black hole in a non-commutative gauge theory. Phys. Lett. B, 838, 137744–9pp.
Abstract: In this work, we study the thermodynamic properties on a non-commutative background via gravitational gauge field potentials. This procedure is accomplished after contracting de Sitter (dS) group, SO(4, 1), with the Poincare group, ISO(3, 1). Particularly, we focus on a static spherically symmetric black hole. In this manner, we calculate the modified Hawking temperature and the other deformed thermal state quantities, namely, entropy, heat capacity, Helmholtz free energy and pressure. Finally, we also investigate the black hole evaporation process in such a context.
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Araujo, M. C., Furtado, J., & Maluf, R. V. (2023). Lorentz-violating extension of scalar QED at finite temperature. Phys. Lett. B, 844, 138064–6pp.
Abstract: In this work, we calculate the one-loop self-energy corrections to the gauge field in scalar electrodynamics modified by Lorentz-violating terms within the framework of the standard model extension (SME). We focus on both CP T-even and CP T-odd contributions. The kinetic part of the scalar sector contains a CP T-even symmetric Lorentz-breaking tensor, and the interaction terms include a vector contracted with the usual covariant derivative in a gauge-invariant manner. We computed the one-loop radiative corrections using dimensional regularization for both the CP T-even and CP T-odd cases. Additionally, we employed the Matsubara formalism to account for finite temperature effects.
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Arbelaez, C., Carcamo Hernandez, A. E., Cepedello, R., Kovalenko, S., & Schmidt, I. (2020). Sequentially loop suppressed fermion masses from a single discrete symmetry. J. High Energy Phys., 06(6), 043–24pp.
Abstract: We propose a systematic and renormalizable sequential loop suppression mechanism to generate the hierarchy of the Standard Model fermion masses from one discrete symmetry. The discrete symmetry is sequentially softly broken in order to generate one-loop level masses for the bottom, charm, tau and muon leptons and two-loop level masses for the lightest Standard Model charged fermions. The tiny masses for the light active neutrinos are produced from radiative type-I seesaw mechanism, where the Dirac mass terms are effectively generated at two-loop level.
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Arbelaez, C., Dib, C., Monsalvez-Pozo, K., & Schmidt, I. (2021). Quasi-Dirac neutrinos in the linear seesaw model. J. High Energy Phys., 07(7), 154–22pp.
Abstract: We implement a minimal linear seesaw model (LSM) for addressing the Quasi-Dirac (QD) behaviour of heavy neutrinos, focusing on the mass regime of M-N less than or similar to M-W. Here we show that for relatively low neutrino masses, covering the few GeV range, the same-sign to opposite-sign dilepton ratio, R-ll, can be anywhere between 0 and 1, thus signaling a Quasi-Dirac regime. Particular values of R-ll are controlled by the width of the QD neutrino and its mass splitting, the latter being equal to the light-neutrino mass m(nu) in the LSM scenario. The current upper bound on m(nu 1) together with the projected sensitivities of current and future |U-N l|(2) experimental measurements, set stringent constraints on our low-scale QD mass regime. Some experimental prospects of testing the model by LHC displaced vertex searches are also discussed.
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Arbelaez, C., Cepedello, R., Helo, J. C., Hirsch, M., & Kovalenko, S. (2022). How many 1-loop neutrino mass models are there? J. High Energy Phys., 08(8), 023–29pp.
Abstract: It is well-known that at tree-level the d = 5 Weinberg operator can be generated in exactly three different ways, the famous seesaw models. In this paper we study the related question of how many phenomenologically consistent 1-loop models one can construct at d=5. First, we discuss that there are two possible classes of 1-loop neutrino mass models, that allow avoiding stable charged relics: (i) models with dark matter candidates and (ii) models with “exits”. Here, we define “exits” as particles that can decay into standard model fields. Considering 1-loop models with new scalars and fermions, we find in the dark matter class a total of (115+203) models, while in the exit class we find (38+368) models. Here, 115 is the number of DM models, which require a stabilizing symmetry, while 203 is the number of models which contain a dark matter candidate, which maybe accidentally stable. In the exit class the 38 refers to models, for which one (or two) of the internal particles in the loop is a SM field, while the 368 models contain only fields beyond the SM (BSM) in the neutrino mass diagram. We then study the RGE evolution of the gauge couplings in all our 1-loop models. Many of the models in our list lead to Landau poles in some gauge coupling at rather low energies and there is exactly one model which unifies the gauge couplings at energies above 10(15) GeV in a numerically acceptable way.
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Archidiacono, M., Giusarma, E., Hannestad, S., & Mena, O. (2013). Cosmic Dark Radiation and Neutrinos. Adv. High. Energy Phys., 2013, 191047–14pp.
Abstract: New measurements of the cosmic microwave background (CMB) by the Planck mission have greatly increased our knowledge about the universe. Dark radiation, a weakly interacting component of radiation, is one of the important ingredients in our cosmological model which is testable by Planck and other observational probes. At the moment, the possible existence of dark radiation is an unsolved question. For instance, the discrepancy between the value of the Hubble constant, H-0, inferred from the Planck data and local measurements of H-0 can to some extent be alleviated by enlarging the minimal ACDM model to include additional relativistic degrees of freedom. From a fundamental physics point of view, dark radiation is no less interesting. Indeed, it could well be one of the most accessible windows to physics beyond the standard model, for example, sterile neutrinos. Here, we review the most recent cosmological results including a complete investigation of the dark radiation sector in order to provide an overview of models that are still compatible with new cosmological observations. Furthermore, we update the cosmological constraints on neutrino physics and dark radiation properties focusing on tensions between data sets and degeneracies among parameters that can degrade our information or mimic the existence of extra species.
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Archidiacono, M., Gariazzo, S., Giunti, C., Hannestad, S., & Tram, T. (2020). Sterile neutrino self-interactions: H-0 tension and short-baseline anomalies. J. Cosmol. Astropart. Phys., 12(12), 029–20pp.
Abstract: Sterile neutrinos with a mass in the eV range have been invoked as a possible explanation of a variety of short baseline (SBL) neutrino oscillation anomalies. However, if one considers neutrino oscillations between active and sterile neutrinos, such neutrinos would have been fully thermalised in the early universe, and would be therefore in strong conflict with cosmological bounds. In this study we first update cosmological bounds on the mass and energy density of eV-scale sterile neutrinos. We then perform an updated study of a previously proposed model in which the sterile neutrino couples to a new light pseudoscalar degree of freedom. Consistently with previous analyses, we find that the model provides a good fit to all cosmological data and allows the high value of H-0 measured in the local universe to be consistent with measurements of the cosmic microwave background. However, new high l polarisation data constrain the sterile neutrino mass to be less than approximately 1 eV in this scenario. Finally, we combine the cosmological bounds on the pseudoscalar model with a Bayesian inference analysis of SBL data and conclude that only a sterile mass in narrow ranges around 1 eV remains consistent with both cosmology and SBL data.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurements of the S-wave fraction in B-0 -> K+ pi(-) mu(+) mu(-) decays and the B-0 -> K*(892)(0) mu(+) mu(-) differential branching fraction. J. High Energy Phys., 11(11), 047–30pp.
Abstract: A measurement of the differential branching fraction of the decay B-0 -> K* (892)(0) mu(+)mu(-) is presented together with a determination of the S-wave fraction of the K+ pi(-) system in the decay B-0 -> K+ pi-mu(+)mu(-). The analysis is based on pp-collision data corresponding to an integrated luminosity of 3 fb(-1) collected with the LHCb experiment. The measurements are made in bins of the invariant mass squared of the dimuon system, q(2). Precise theoretical predictions for the differential branching fraction of B-0 -> K* (892)(0) mu(+) mu(-) decays are available for the q(2) region 1.1 < q(2) < 6.0 GeV2/c(4). In this q(2) region, for the K+pi(-) invariant mass range 796 < m(K pi) < 996MeV/c(2), the S-wave fraction of the K+pi(-) system in B-0 -> K+pi(-)mu(+)mu(-) decays is found to be F-S – 0.101 +/- 0.017(stat) +/- 0: 009(syst), and the differential branching fraction of B-0 -> K* (892)(0) mu(+)mu(-) decays is determined to be dB/dq(2) = (0.392(-0.019)(+ 0.020)(stat) +/- 0.010(syst) +/- 0.027(norm)) x 10(-7) c(4)/GeV2. The differential branching fraction measurements presented are the most precise to date and are found to be in agreement with Standard Model predictions.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurement of the B-s(0) -> J/Psi eta lifetime. Phys. Lett. B, 762, 484–492.
Abstract: Using a data set corresponding to an integrated luminosity of 3fb(-1), collected by the LHCb experiment in ppcollisions at centre-of-mass energies of 7 and 8TeV, the effective lifetime in the B-s(0) -> J/Psi eta decay mode, teff, is measured to be tau(eff) = 1.479 +/- 0.034 (stat)+/- 0.011 (syst) ps. Assuming CP conservation, tau(eff) corresponds to the lifetime of the light B-s(0) mass eigenstate. This is the first measurement of the effective lifetime in this decay mode.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurement of the ratio of branching fractions B(B-c(+) -> J/psi K+)/B(B-c(+) -> J/psi pi(+)). J. High Energy Phys., 09(9), 153–15pp.
Abstract: The ratio of branching fractions R-K/pi = B (B-c(+) -> J/psi K+)/B(B-c(+) -> J/psi pi(+)) is measured with pp collision data collected by the LHCb experiment at centre-of-mass energies of 7TeV and 8TeV, corresponding to an integrated luminosity of 3 fb(-1). It is found to be R-K/pi = 0.079 +/- 0.007 +/- 0.003, where the first uncertainty is statistical and the second is systematic. This measurement is consistent with the previous LHCb result, while the uncertainties are significantly reduced.
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