Rocha-Moran, P., & Vicente, A. (2019). Lepton flavor violation in a Z ' model for the b -> s anomalies. Phys. Rev. D, 99(3), 035016–10pp.
Abstract: In recent years, several observables associated to semileptonic b -> s processes have been found to depart from their predicted values in the Standard Model, including a few tantalizing hints of lepton flavor universality violation. In this work, we consider an existing model with a massive Z' boson that addresses the anomalies in b -> s transitions and extend it with a nontrivial embedding of neutrino masses. We analyze lepton flavor-violating effects, induced by the nonuniversal interaction associated to the b -> s anomalies and by the new physics associated to the neutrino mass generation, and determine the expected ranges for the most relevant observables.
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Dai, L. R., Pavao, R., Sakai, S., & Oset, E. (2019). tau(-) -> nu tau M1 M2, with M1, M2 pseudoscalar or vector mesons. Eur. Phys. J. A, 55(2), 20–22pp.
Abstract: .We perform a calculation of the -M1M2, with M1,M2 either pseudoscalar or vector mesons using the basic weak interaction and angular momentum algebra to relate the different processes. The formalism also leads to a different interpretation of the role played by G-parity in these decays. We also observe that, while PPp-wave production is compatible with chiral perturbation theory and experiment, VP and VVp-wave production is clearly incompatible with experiment and we develop the formalism also in this case, producing the VP or VV pairs in s-wave. We compare our results with experiment and other theoretical approaches for rates and invariant mass distributions and make predictions for unmeasured decays. We show the value of these reactions, particularly if the M1M2 mass distribution is measured, as a tool to learn about the meson-meson interaction and the nature of some resonances, coupling to two mesons, which are produced in such decays.
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Carcamo Hernandez, A. E., Kovalenko, S., Valle, J. W. F., & Vaquera-Araujo, C. A. (2019). Neutrino predictions from a left-right symmetric flavored extension of the standard model. J. High Energy Phys., 02(2), 065–24pp.
Abstract: We propose a left-right symmetric electroweak extension of the Standard Model based on the Delta (27) family symmetry. The masses of all electrically charged Standard Model fermions lighter than the top quark are induced by a Universal Seesaw mechanism mediated by exotic fermions. The top quark is the only Standard Model fermion to get mass directly from a tree level renormalizable Yukawa interaction, while neutrinos are unique in that they get calculable radiative masses through a low-scale seesaw mechanism. The scheme has generalized μ- tau symmetry and leads to a restricted range of neutrino oscillations parameters, with a nonzero neutrinoless double beta decay amplitude lying at the upper ranges generically associated to normal and inverted neutrino mass ordering.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2019). Prompt Lambda+c production in pPb collisions at root s(NN)=5.02 TeV. J. High Energy Phys., 02(2), 102–26pp.
Abstract: The prompt production of +c baryons is studied in proton- lead collisions collected with the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of 1 : 58 nb recorded at a nucleon- nucleon centre- of- mass energy of p sNN = 5 : 02TeV. Measurements of the di ff erential cross- section and the forwardbackward production ratio are reported for +c baryons with transverse momenta in the range 2 < pT < 10 GeV =c and rapidities in the ranges 1 : 5 < y < 4 : 0 and 4 : 5 < y < 2 : 5 in the nucleon- nucleon centre- of- mass system. The ratio of cross- sections of +c baryons and D0 mesons is also reported. The results are compared with next- to- leading order calculations that use nuclear parton distribution functions.
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Alvarez-Ruso, L., Graczyk, K. M., & Saul-Sala, E. (2019). Nucleon axial form factor from a Bayesian neural-network analysis of neutrino-scattering data. Phys. Rev. C, 99(2), 025204–14pp.
Abstract: The Bayesian approach for feedforward neural networks has been applied to the extraction of the nucleon axial form factor from the neutrino-deuteron-scattering data measured by the Argonne National Laboratory bubble-chamber experiment. This framework allows to perform a model-independent determination of the axial form factor from data. When the low 0.05 < Q(2) < 0.10-GeV2 data are included in the analysis, the resulting axial radius disagrees with available determinations. Furthermore, a large sensitivity to the corrections from the deuteron structure is obtained. In turn, when the low-Q(2) region is not taken into account with or without deuteron corrections, no significant deviations from previous determinations have been observed. A more accurate determination of the nucleon axial form factor requires new precise measurements of neutrino-induced quasielastic scattering on hydrogen and deuterium.
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Elor, G., Escudero, M., & Nelson, A. E. (2019). Baryogenesis and dark matter from B mesons. Phys. Rev. D, 99(3), 035031–18pp.
Abstract: We present a new mechanism of baryogenesis and dark matter production in which both the dark matter relic abundance and the baryon asymmetry arise from neutral B meson oscillations and subsequent decays. This setup is testable at hadron colliders and B factories. In the early universe, decays of a long lived particle produce B mesons and antimesons out of thermal equilibrium. These mesons/antimesons then undergo CP violating oscillations before quickly decaying into visible and dark sector particles. Dark matter will be charged under the baryon number so that the visible sector baryon asymmetry is produced without violating the total baryon number of the Universe. The produced baryon asymmetry will be directly related to the leptonic charge asymmetry in neutral B decays: an experimental observable. Dark matter is stabilized by an unbroken discrete symmetry, and proton decay is simply evaded by kinematics. We will illustrate this mechanism with a model that is unconstrained by dinucleon decay, does not require a high reheat temperature, and would have unique experimental signals-a positive leptonic asymmetry in B meson decays, a new decay of B mesons into a baryon and missing energy, and a new decay of b-flavored baryons into mesons and missing energy. These three observables are testable at current and upcoming collider experiments, allowing for a distinct probe of this mechanism.
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Afonso, V. I., Olmo, G. J., Orazi, E., & Rubiera-Garcia, D. (2019). Correspondence between modified gravity and general relativity with scalar fields. Phys. Rev. D, 99(4), 044040–15pp.
Abstract: We describe a novel procedure to map the field equations of nonlinear Ricci-based metric-affine theories of gravity, coupled to scalar matter described by a given Lagrangian, into the field equations of general relativity coupled to a different scalar field Lagrangian. Our analysis considers examples with a single and N real scalar fields, described either by canonical Lagrangians or by generalized functions of the kinetic and potential terms. In particular, we consider several explicit examples involving foRthorn theories and the Eddington-inspired Born-Infeld gravity model, coupled to different scalar field Lagrangians. We show how the nonlinearities of the gravitational sector of these theories can be traded to nonlinearities in the matter fields and how the procedure allows to find new solutions on both sides of the correspondence. The potential of this procedure for applications of scalar field models in astrophysical and cosmological scenarios is highlighted.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). Search for CP violation through an amplitude analysis of D-0 K+K-+- decays. J. High Energy Phys., 02(2), 126–34pp.
Abstract: A search for CP violation in the Cabibbo-suppressed D-0 K+K-+- decay mode is performed using an amplitude analysis. The measurement uses a sample of pp collisions recorded by the LHCb experiment during 2011 and 2012, corresponding to an integrated luminosity of 3.0 fb(-1). The D-0 mesons are reconstructed from semileptonic b-hadron decays into D0-X final states. The selected sample contains more than 160 000 signal decays, allowing the most precise amplitude modelling of this D-0 decay to date. The obtained amplitude model is used to perform the search for CP violation. The result is compatible with CP symmetry, with a sensitivity ranging from 1% to 15% depending on the amplitude considered.
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Driencourt-Mangin, F., Rodrigo, G., Sborlini, G. F. R., & Torres Bobadilla, W. J. (2019). Universal four-dimensional representation of H -> gamma gamma at two loops through the Loop-Tree Duality. J. High Energy Phys., 02(2), 143–39pp.
Abstract: We extend useful properties of the H unintegrated dual amplitudes from one- to two-loop level, using the Loop-Tree Duality formalism. In particular, we show that the universality of the functional form regardless of the nature of the internal particle still holds at this order. We also present an algorithmic way to renormalise two-loop amplitudes, by locally cancelling the ultraviolet singularities at integrand level, thus allowing a full four-dimensional numerical implementation of the method. Our results are compared with analytic expressions already available in the literature, finding a perfect numerical agreement. The success of this computation plays a crucial role for the development of a fully local four-dimensional framework to compute physical observables at Next-to-Next-to Leading order and beyond.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2019). Search for a Stable Six-Quark State at BABAR. Phys. Rev. Lett., 122(7), 072002–7pp.
Abstract: Recent investigations have suggested that the six-quark combination uuddss could be a deeply bound state (S) that has eluded detection so far, and a potential dark matter candidate. We report the first search for a stable, doubly strange six-quark state in (sic) > S (Lambda) over bar(Lambda) over bar decays based on a sample of 90 x 10(6)(sic)(2S) and 110 x 10(6)(sic)(3S) decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined (sic)(2S, 3S) -> S (Lambda) over bar(Lambda) over bar branching fraction in the range (1.2-1.4) x 10(-7) are derived for m(s) < 2.05 GeV. These bounds set stringent limits on the existence of such exotic particles.
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