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Beltran-Palau, P., del Rio, A., & Navarro-Salas, J. (2023). Quantum corrections to the Schwarzschild metric from vacuum polarization. Phys. Rev. D, 107(8), 085023–15pp.
Abstract: We explore static and spherically symmetric solutions of the 4-dimensional semiclassical Einstein's equations using the quantum vacuum polarization of a conformal field as a source. These solutions may be of interest for the study of exotic compact objects (ECOs). The full backreaction problem is addressed by solving the semiclassical Tolman-Oppenheimer-Volkoff (TOV) equations making use of effective equations of state inspired by the trace anomaly and an extra simplifying and reasonable assumption. We combine analytical and numerical techniques to solve the resulting differential equations, both perturbatively and nonperturbatively in h. In all cases the solution is similar to the Schwarzschild metric up p ffiffito the vicinity of the classical horizon r = 2M. However, at r = 2M + epsilon, with epsilon similar to O(root h), we find a coordinate singularity. In the case of matching with a static star, this leads to an upper bound in the compactness, and sets a constraint on the family of stable ECOs. We also study the corrections that the quantum-vacuum polarization induces on the propagation of waves, and discuss the implications. For the pure vacuum case, we can further extend the solution by using appropriate coordinates until we reach another singular point, where this time a null curvature singularity arises and prevents extending beyond. This picture qualitatively agrees with the results obtained in the effective two-dimensional approach, and reinforces the latter as a reasonable method.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Search for K0S(L)→μ+μ−μ+μ− decays at LHCb. Phys. Rev. D, 108, L031102–12pp.
Abstract: A search for K0S(L)→μ+μ−μ+μ− decays is performed using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.1 fb−1. No evidence for signal is found. The 90% confidence level upper limits are the first set for both decays and are B(K0S→μ+μ−μ+μ−)<5.1×10−12 and B(K0L→μ+μ−μ+μ−)<2.3×10−9.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Amplitude analysis of B0 -> D0bar Ds+ pi- and B+ -> D- Ds+ pi+ decays. Phys. Rev. D, 108(1), 012017–30pp.
Abstract: Resonant contributions in B0 & RARR; over bar D0D+s & pi;- and B+ & RARR; D-D+s & pi;+ decays are determined with an amplitude analysis, which is performed both separately and simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near 2.9 GeV, are observed in the Ds & pi; decay channel.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Barranco Navarro, L., Cabrera Urban, S., et al. (2023). Measurement of the inclusive t(t)over-bar production cross section in the lepton plus jets channel in pp collisions at √s=7 TeV with the ATLAS detector using support vector machines. Phys. Rev. D, 108(3), 032014–34pp.
Abstract: A measurement of the top quark pair-production cross section in the lepton + jets decay channel is presented. It is based on 4.6 fb(-1) of root s = 7 TeV pp collision data collected during 2011 by the ATLAS experiment at the CERN Large Hadron Collider. A three-class, multidimensional event classifier based on support vector machines is used to differentiate t (T) over bar events from backgrounds. The tt production cross section is found to be sigma(t (t) over bar) = 168.5 +/- 0.7(stat)(-5.9)(+6.2) (syst)(-3.2)(+3.4) (lumi) pb. The result is consistent with the Standard Model prediction based on QCD calculations at next-to-next-to-leading order.
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Malabarba, B. B., Khemchandani, K. P., Martinez Torres, A., & Oset, E. (2023). D1(2420) and its interactions with a kaon: Open charm states with strangeness. Phys. Rev. D, 107(3), 036016–12pp.
Abstract: In this work we present an attempt to describe the X1(2900) found by the LHCb collaboration, in the experimental data on the invariant mass spectrum of D-K+, as a three-meson molecular state of the KpD over line system. We discuss that the interactions in all the subsystems are attractive in nature, with the pD over line interaction generating over line D1(2420) and the Kp resonating as K1(1270). We find that the system can form a three-body state but with a mass higher than that of X1(2900). We investigate the KpD system too, finding that the three-body dynamics generates an isoscalar state, which can be related to D*s1(2860), and an exotic isovector state. This latter state has a mass similar to that of the X0(2900) and X1(2900) states found by LHCb, but a very small width (similar to 7.4 +/- 0.9 MeV) and necessarily requires more than two quarks to describe its properties. We hope that our findings will encourage experimental investigations of the isovector KpD state. Finally, in the pursuit of finding a description for X1(2900), we study the K over line K*D* system where over line K*D* forms 0+, 1+, and 2+ states. We do not find a state that can be associated with X1(2900).
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Araujo Filho, A. A., Nascimento, J. R., Petrov, A. Y., & Porfírio, P. J. (2023). Vacuum solution within a metric-affine bumblebee gravity. Phys. Rev. D, 108(8), 085010–13pp.
Abstract: We consider a metric-affine extension to the gravitational sector of the Standard Model extension for the Lorentz-violating coefficients u and s(mu nu). The general results, which are applied to a specific model called metric-affine bumblebee gravity, are obtained. A Schwarzschild-like solution, incorporating effects of the Lorentz symmetry breaking through the coefficient X = xi b(2), is found. Furthermore, a complete study of the geodesic trajectories of particles is accomplished in this background, emphasizing the departure from general relativity. We also compute the advance of Mercury's perihelion and the deflection of light within the context of the weak-field approximation, and we verify that there exist two new contributions ascribed to the Lorentz symmetry breaking. As a phenomenological application, we compare our theoretical results with observational data in order to estimate the coefficient X.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). First observation of the B+→D+sD−sK+ decay. Phys. Rev. D, 108, 034012–14pp.
Abstract: The B+→D+sD−sK+ decay is observed for the first time using proton-proton collision data collected by the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb−1. Its branching fraction relative to that of the B+→D+D−K+ decay is measured to be B(B+→D+sD−sK+)B(B+→D+D−K+)=0.525±0.033±0.027±0.034, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the D±s→K∓K±π± and D±→K∓π±π± decays. This measurement fills an experimental gap in the knowledge of the family of Cabibbo-favored ¯b→¯cc¯s transitions and opens the path for unique studies of spectroscopy in future.
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Dutka, T. P., & Gargalionis, J. (2023). Dimension-five baryon-number violation in low-scale Pati-Salam models. Phys. Rev. D, 107(3), 035019–10pp.
Abstract: The gauge bosons of the Pati-Salam model do not mediate proton decay at the renormalizable level, and for this reason it is possible to construct scenarios in which SU(4) (R) SU(2)R is broken at relatively low scales. In this paper we show that such low-scale models generate dimension-five operators that can give rise to nucleon decays at unacceptably large rates, even if the operators are suppressed by the Planck scale. We find an interesting complementarity between the nucleon-decay limits and the usual meson-decay constraints. Furthermore, we argue that these operators are generically present when the model is embedded into SO(10), lowering the suppression scale. Under reasonable assumptions, the lower limit on the breaking scale can be constrained to be as high as O(108) GeV.
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Molina, R., & Oset, E. (2023). T-cS (2900) as a threshold effect from the interaction of the D* K *, D *(s)rho channels. Phys. Rev. D, 107(5), 056015–7pp.
Abstract: We look at the mass distribution of the D(S)(+)i Pi(-) In the B-0 ->(DDS+)-D-0 Pi(-)decay, where a peak has been observed in the region of the D (*) (s)rho, D* K* thresholds. By creating these two channels together with a D (0) in B-0 decay and letting them interact as coupled channels, we obtain a structure around their thresholds, short of producing a bound state, which leads to a peak in the D-S(+) Pi(-)mass distribution in the B-0 -> (DDS+)-D-0 Pi(-)decay. We conclude that the interaction between the D*K* and D (*) (s)rho is essential to produce the cusp structure that we associate to the recently seen Tcs(2900), and that its experimental width is mainly due to the decay width of the rho meson. The peak obtained together with a smooth background reproduces fairly well the experimental mass distribution observed in the B (0)-> (DDS+)-D-0 Pi(-) decay.
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DUNE Collaboration(Abud, A. A. et al), Amedo, P., Antonova, M., Barenboim, G., Cervera-Villanueva, A., De Romeri, V., et al. (2023). Identification and reconstruction of low-energy electrons in the ProtoDUNE-SP detector. Phys. Rev. D, 107(9), 092012–22pp.
Abstract: Measurements of electrons from ?e interactions are crucial for the Deep Underground Neutrino Experiment (DUNE) neutrino oscillation program, as well as searches for physics beyond the standard model, supernova neutrino detection, and solar neutrino measurements. This article describes the selection and reconstruction of low-energy (Michel) electrons in the ProtoDUNE-SP detector. ProtoDUNE-SP is one of the prototypes for the DUNE far detector, built and operated at CERN as a charged particle test beam experiment. A sample of low-energy electrons produced by the decay of cosmic muons is selected with a purity of 95%. This sample is used to calibrate the low-energy electron energy scale with two techniques. An electron energy calibration based on a cosmic ray muon sample uses calibration constants derived from measured and simulated cosmic ray muon events. Another calibration technique makes use of the theoretically well-understood Michel electron energy spectrum to convert reconstructed charge to electron energy. In addition, the effects of detector response to low-energy electron energy scale and its resolution including readout electronics threshold effects are quantified. Finally, the relation between the theoretical and reconstructed low-energy electron energy spectra is derived, and the energy resolution is characterized. The low-energy electron selection presented here accounts for about 75% of the total electron deposited energy. After the addition of lost energy using a Monte Carlo simulation, the energy resolution improves from about 40% to 25% at 50 MeV. These results are used to validate the expected capabilities of the DUNE far detector to reconstruct low-energy electrons.
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