Heidari, N., Hassanabadi, H., Araujo Filho, A. A., & Kriz, J. (2024). Exploring non-commutativity as a perturbation in the Schwarzschild black hole: quasinormal modes, scattering, and shadows. Eur. Phys. J. C, 84(6), 566–11pp.
Abstract: In this work, by a novel approach to studying the scattering of a Schwarzschild black hole, the non-commutativity is introduced as perturbation. We begin by reformulating the Klein-Gordon equation for the scalar field in a new form that takes into account the deformed non-commutative spacetime. Using this formulation, an effective potential for the scattering process is derived. To calculate the quasinormal modes, we employ the WKB method and also utilize fitting techniques to investigate the impact of non-commutativity on the scalar quasinormal modes. We thoroughly analyze the results obtained from these different methods. Moreover, the greybody factor and absorption cross section are investigated. Additionally, we explore the behavior of null geodesics in the presence of non-commutativity. Specifically, we examine the photonic, and shadow radius as well as the light trajectories for different non-commutative parameters. Therefore, by addressing these various aspects, we aim to provide a comprehensive understanding of the influence of non-commutativity on the scattering of a Schwarzschild-like black hole and its implications for the behavior of scalar fields and light trajectories.
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Silva, J. E. G., Yesiltas, O., Furtado, J., & Araujo Filho, A. A. (2024). Strain effects on the electronic properties of a graphene wormhole. Eur. Phys. J. Plus, 139(8), 762–16pp.
Abstract: In this work, we explore the strain and curvature effects on the electronic properties of a curved graphene structure, called the graphene wormhole. The electron dynamics is described by a massless Dirac fermion containing position-dependent Fermi velocity. In addition, the strain produces a pseudo-magnetic vector potential to the geometric coupling. For an isotropic strain tensor, the decoupled components of the spinor field exhibit a supersymmetric (SUSY) potential, depending on the centrifugal term and the external magnetic field only. In the absence of an external magnetic field, the strain yields an exponentially damped amplitude, whereas the curvature leads to a power-law damping of the wave function. The spin-curvature coupling breaks the chiral symmetry between the upper and the lower spinor component, which leads to the increasing of the wave function on either upper or lower region of the wormhole, i.e., depending on the spin number. By adding a uniform magnetic field, the effective potential exhibits an asymptotic quadratic profile and a spin-curvature barrier near the throat. As a result, the bound states (Landau levels) are confined around the wormhole throat showing an asymmetric and spin-dependent profile.
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Belen Galan, M., Alvarez-Ruso, L., Rafi Alam, M., Ruiz Simo, I., & Vicente Vacas, M. J. (2024). Cabibbo suppressed hyperon production off nuclei induced by antineutrinos. Phys. Rev. D, 109(3), 033001–13pp.
Abstract: In this work, we study the production of E and A hyperons in strangeness -changing AS = -1 chargedcurrent interactions of muon antineutrinos on nuclear targets. At the nucleon level, besides quasielastic scattering, we consider the inelastic mechanism in which a pion is produced alongside the hyperon. Its relevance for antineutrinos with energies below 2 GeV is conveyed in integrated and differential cross sections. We observe that the distributions on the angle between the hyperon and the final lepton are clearly different for quasielastic and inelastic processes. Hyperon final -state interactions, modeled with an intranuclear cascade, lead to a significant transfer from primary produced E's into final A's. They also cause considerable energy loss, which is apparent in hyperon energy distributions. We have investigated A production off 40Ar in the conditions of the recently reported MicroBooNE measurement. We find that the A pi contribution, dominated by E*(1385) excitation, accounts for about one third of the cross section.
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ATLAS Collaboration(Aad, G. et al), Aikiot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2024). Measurements of inclusive and differential cross-sections of t(t)over-barγ production in pp collisions at √s=13 TeV with the ATLAS detector. J. High Energy Phys., 10(10), 191–77pp.
Abstract: Inclusive and differential cross-sections are measured at particle level for the associated production of a top quark pair and a photon (t (t) over bar gamma). The analysis is performed using an integrated luminosity of 140 fb(-1) of proton-proton collisions at a centre-of-mass energy of 13TeV collected by the ATLAS detector. The measurements are performed in the single-lepton and dilepton top quark pair decay channels focusing on t (t) over bar gamma topologies where the photon is radiated from an initial-state parton or one of the top quarks. The absolute and normalised differential cross-sections are measured for several variables characterising the photon, lepton and jet kinematics as well as the angular separation between those objects. The observables are found to be in good agreement with the Monte Carlo predictions. The photon transverse momentum differential distribution is used to set limits on effective field theory parameters related to the electroweak dipole moments of the top quark. The combined limits using the photon and the Z boson transverse momentum measured in t (t) over bar production in associations with a Z boson are also set.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2024). Beam-induced backgrounds measured in the ATLAS detector during local gas injection into the LHC beam vacuum. J. Instrum., 19(6), P06014–60pp.
Abstract: Inelastic beam-gas collisions at the Large Hadron Collider (LHC), within a few hundred metres of the ATLAS experiment, are known to give the dominant contribution to beam backgrounds. These are monitored by ATLAS with a dedicated Beam Conditions Monitor (BCM) and with the rate of fake jets in the calorimeters. These two methods are complementary since the BCM probes backgrounds just around the beam pipe while fake jets are observed at radii of up to several metres. In order to quantify the correlation between the residual gas density in the LHC beam vacuum and the experimental backgrounds recorded by ATLAS, several dedicated tests were performed during LHC Run 2. Local pressure bumps, with a gas density several orders of magnitude higher than during normal operation, were introduced at different locations. The changes of beam-related backgrounds, seen in ATLAS, are correlated with the local pressure variation. In addition the rates of beam-gas events are estimated from the pressure measurements and pressure bump profiles obtained from calculations. Using these rates, the efficiency of the ATLAS beam background monitors to detect beam-gas events is derived as a function of distance from the interaction point. These efficiencies and characteristic distributions of fake jets from the beam backgrounds are found to be in good agreement with results of beam-gas simulations performed with the Fluka Monte Carlo programme.
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