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de Anda, F. J., Medina, O., Valle, J. W. F., & Vaquera-Araujo, C. A. (2022). Scotogenic Majorana neutrino masses in a predictive orbifold theory of flavor. Phys. Rev. D, 105(5), 055030–12pp.
Abstract: The use of extra space-time dimensions provides a promising approach to the flavor problem. The chosen compactification of a 6-dimensional orbifold implies a remnant family symmetry A4. This makes interesting predictions for quark and lepton masses, for neutrino oscillations and neutrinoless double beta decay, providing also a very good global description of all flavor observables. Due to an auxiliary Z4 symmetry, we implement a scotogenic Majorana neutrino mass generation mechanism with a viable WIMP dark matter candidate.
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De Romeri, V., Puerta, M., & Vicente, A. (2022). Dark matter in a charged variant of the Scotogenic model. Eur. Phys. J. C, 82(7), 623–16pp.
Abstract: Scotogenic models are among the most popular possibilities to link dark matter and neutrino masses. In this work we discuss a variant of the Scotogenic model that includes charged fermions and a doublet with hypercharge 3/2. Neutrino masses are induced at the one-loop level thanks to the states belonging to the dark sector. However, in contrast to the standard Scotogenic model, only the scalar dark matter candidate is viable in this version. After presenting the model and explaining some particularities about neutrino mass generation, we concentrate on its dark matter phenomenology. We show that the observed dark matter relic density can be correctly reproduced in the usual parameter space regions found for the standard Scotogenic model or the Inert Doublet model. In addition, the presence of the charged fermions opens up new viable regions, not present in the original scenarios, provided some tuning of the parameters is allowed.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Observation of the Decay Lambda(0)(b) -> Lambda(+)(c) tau(-)(nu)over-bar(tau). Phys. Rev. Lett., 128(19), 191803–11pp.
Abstract: The first observation of the semileptonic b-baryon decay Lambda(0)(b) -> Lambda(+)(c) tau(-)(nu) over bar (tau) with a significance of 6.1 sigma, is reported using a data sample corresponding to 3 fb(-1) of integrated luminosity, collected by the LHCb experiment at center-of-mass energies of 7 and 8 TeV at the LHC. The tau(-) lepton is reconstructed in the hadronic decay to three charged pions. The ratio K = B(Lambda(0)(b) -> Lambda(+)(c) tau(-)(nu) over bar (tau))/B(Lambda(0)(b) -> Lambda(+)(c)pi(-)pi(+)pi(-)) is measured to be 2.46 +/- 0.27 +/- 0.40, where the first uncertainty is statistical and the second systematic. The branching fraction B(Lambda(0)(b) -> Lambda(+)(c) tau(-)(nu) over bar (tau)) (1.50 +/- 0.16 +/- 0.25 +/- 0.23)% is obtained, where the third uncertainty is from the external branching fraction of the normalization channel Lambda(0)(b) -> Lambda(+)(c)pi(-)pi(+)pi(-). The ratio of semileptonic branching fractions R(Lambda(+)(c)) B(Lambda(0)(b) -> Lambda(+)(c) tau(-)(nu) over bar (tau))/B(Lambda(0)(b) -> Lambda(+)(c)mu(-)(nu) over bar (tau)) is derived to be 0.242 +/- 0.026 +/- 0.040 +/- 0.059, where the external branching fraction uncertainty from the channel Lambda(0)(b) -> Lambda(+)(c)mu(-)(nu) over bar (tau) contributes to the last term. This result is in agreement with the standard model prediction.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Vidal, J., et al. (2022). Measurement of the charm mixing parameter y(CP)-y(CP)(K pi) using two-body D-0 meson decays. Phys. Rev. D, 105(9), 092013–17pp.
Abstract: A measurement of the ratios of the effective decay widths of D-0 -> pi(-)pi(+) and D-0 -> K- K+ decays over that of D-0 -> K-pi(+) decays is performed with the LHCb experiment using proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb(-1). These observables give access to the charm mixing parameters y(CP)(pi pi) – y(CP)(K pi )and y(CP)(KK) -y(CP)(K pi), and are measured as y(CP)(pi pi) – y(CP)(K pi) = (6.57 +/- 0.53 +/- 0.16) x 10(-3), y(CP)(KK) – y(CP)(K pi) = (7.08 +/- 0.30 +/- 0.14) x 10(-3), where the first uncertainties are statistical and the second systematic. The combination of the two measurements is Y-CP – y(CP)(K pi) = (6.96 +/- 0.26 +/- 0.13) x 10(-3), which is four times more precise than the previous world average.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Study of charmonium and charmonium-like contributions in B+ -> J/psi eta K+ decays. J. High Energy Phys., 04(4), 046–29pp.
Abstract: A study of B+ -> J/psi eta K+ decays, followed by J/psi -> mu(+)mu(-) and eta -> gamma gamma, is performed using a dataset collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb(-1). The J/psi eta mass spectrum is investigated for contributions from charmonia and charmonium-like states. Evidence is found for the B+ -> (psi(2)(3823) -> J/psi eta)K+ and B+ -> (psi(4040) -> J/psi eta)K+ decays with significance of 3.4 and 4.7 standard deviations, respectively. This constitutes the first evidence for the psi(2)(3823) -> J/psi eta decay.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Observation of the B-0 -> (D)over-bar*K-0(+) pi(-) and B-s(0) -> (D)over-bar*K-0(-)pi(+) decays. Phys. Rev. D, 105(7), 072005–22pp.
Abstract: The first observations of B-0 -> (D) over bar*(2007)K-0(+)pi(-) and B-s(0) -> (D) over bar*(2007)K-0(-)pi(+) decays are presented, and their branching fractions relative to that of the B ->( D) over bar* (2007)(0)pi(+)pi(-) decay are reported. These modes can potentially be used to investigate the spectroscopy of charm and charm-strange resonances and to determine the angle gamma of the Cabibbo-Kobayashi-Maskawa unitarity triangle. It is also important to understand them as a source of potential background in determinations of gamma from B+ -> DK+ and B-0 -> DK+pi(-) decays. The analysis is based on a sample corresponding to an integrated luminosity of 5.4 fb(-1 )of proton-proton collision data at 13 TeV center-of-mass energy recorded with the LHCb detector. The (D) over bar*(2007)(0) mesons are fully reconstructed in the (D) over bar (0)pi(0) and (D) over bar (0)gamma channels with the (D) over bar (0) -> K+pi(-) decay. A novel weighting method is used to subtract background while simultaneously applying an event-by-event efficiency correction to account for resonant structures in the decays.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Precision measurement of forward Z boson production in proton-proton collisions at root s=13 TeV. J. High Energy Phys., 07(7), 026–57pp.
Abstract: A precision measurement of the Z boson production cross-section at root s = 13 TeV in the forward region is presented, using pp collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb(-1). The production cross-section is measured using Z -> mu(+)mu(-) events within the fiducial region defined as pseudorapidity 2.0 < eta < 4.5 and transverse momentum p(T) > 20 GeV/c for both muons and dimuon invariant mass 60 < M-mu μ< 120 GeV/c(2). The integrated cross-section is determined to be sigma(Z -> mu(+)mu(-)) = 196.4 +/- 0.2 +/- 1.6 +/- 3.9 pb, where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions within uncertainties.
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Delhom, A., Nascimento, J. R., Olmo, G. J., Petrov, A. Y., & Porfirio, P. J. (2022). Radiative corrections in metric-affine bumblebee model. Phys. Lett. B, 826, 136932–9pp.
Abstract: We consider the metric-affine formulation of bumblebee gravity, derive the field equations, and show that the connection can be written as Levi-Civita of a disformally related metric in which the bumblebee field determines the disformal part. As a consequence, the bumblebee field gets coupled to all the other matter fields present in the theory, potentially leading to nontrivial phenomenological effects. To explore this issue we compute the weak-field limit and study the resulting effective theory. In this scenario, we couple scalar and spinorial matter to the effective metric which, besides the zeroth-order Minkowskian contribution, also has the vector field contributions of the bumblebee, and show that it is renormalizable at one-loop level. From our analysis it also follows that the non-metricity of this theory is determined by the gradient of the bumblebee field, and that it can acquire a vacuum expectation value due to the contribution of the bumblebee field.
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Delhom, A., Mariz, T., Nascimento, J. R., Olmo, G. J., Petrov, A. Y., & Porfirio, P. J. (2022). Spontaneous Lorentz symmetry breaking and one-loop effective action in the metric-affine bumblebee gravity. J. Cosmol. Astropart. Phys., 07(7), 018–27pp.
Abstract: The metric-affine bumblebee model in the presence of fermionic matter minimally coupled to the connection is studied. We show that the model admits an Einstein frame representation in which the matter sector is described by a non-minimal Dirac action without any analogy in the literature. Such non-minimal terms involve unconventional couplings between the bumblebee and the fermion field. We then rewrite the quadratic fermion action in the Einstein frame in the basis of 16 Dirac matrices in order to identify the coefficients for Lorentz/CPT violation in all orders of the non-minimal coupling xi. The exact result for the fermionic determinant in the Einstein frame, including all orders in xi, is also provided. We demonstrate that the axial contributions are at least of second order in the perturbative expansion of xi. Furthermore, we compute the one-loop effective potential within the weak field approximation.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., et al. (2022). Two-particle Bose-Einstein correlations in pp collisions at root s=13 TeV measured with the ATLAS detector at the LHC. Eur. Phys. J. C, 82(7), 608–38pp.
Abstract: This paper presents studies of Bose-Einstein correlations (BEC) in proton-proton collisions at a centre-of-mass energy of 13 TeV, using data from the ATLAS detector at the CERN Large Hadron Collider. Data were collected in a special low-luminosity configuration with a minimum-bias trigger and a high-multiplicity track trigger, accumulating integrated luminosities of 151 μb(-1) and 8.4 nb(-1), respectively. The BEC are measured for pairs of like-sign charged particles, each with vertical bar eta vertical bar < 2.5, for two kinematic ranges: the first with particle pr > 100 MeV and the second with particle pr > 500 MeV. The BEC parameters, characterizing the source radius and particle correlation strength, are investigated as functions of charged-particle multiplicity (up to 300) and average transverse momentum of the pair (up to 1.5 GeV). The double-differential dependence on charged-particle multiplicity and average transverse momentum of the pair is also studied. The BEC radius is found to be independent of the charged-particle multiplicity for high charged-particle multiplicity (above 100), confirming a previous observation at lower energy. This saturation occurs independent of the transverse momentum of the pair.
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