Browsing by Author "Quintero, Néstor"
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Item Analysis of the nonleptonic charmonium modes Bs0 →j /ψ f2′ (1525) and Bs0 →j /ψK+K-(American Physical Society, 2016-12-07) Morales, César A.; Quintero, Néstor; Vera, Carlos E.; Villalba, AlexisIn this work, we present an analysis of the nonleptonic charmonium modes B 0 s → J / ψ f ′ 2 ( 1525 ) and B 0 s → J / ψ K + K − . Within the framework of the factorization approach and using the perturbative QCD for the evaluation of the relevant form factors, we find a branching fraction for the two-body channel of BR ( B 0 s → J / ψ f ′ 2 ( 1525 ) ) = ( 1.6 + 0.9 − 0.7 ) × 10 − 4 which is in agreement with the experimental values reported by the LHCb and Belle Collaborations. The associated polarization fractions to this vector-tensor mode are also presented. On the other hand, nonresonant and resonant contributions to the three-body decay B 0 s → J / ψ K + K − are carefully investigated. The dominant contributions of the resonances ϕ ( 1020 ) and f ′ 2 ( 1525 ) are properly taken into account. A detailed analysis of the K + K − invariant mass distributions and Dalitz plot are also performed. The overall result BR ( B 0 s → J / ψ K + K − ) = ( 9.3 + 1.3 − 1.1 ) × 10 − 4 is also in satisfactory agreement with the experimental information reported by LHCb and Belle.Item Constraints on lepton number violating short-range interactions from |ΔL| = 2 processes(Elsevier B.V., 2017-01-10) Quintero, NéstorIn this work we study the short-range contributions that induce effective lepton number violating (LNV) interactions. We obtain a full set of constraints on the effective short-range couplings from a large variety of low-energy |ΔL|=2 processes of pseudoscalar mesons K,D,Ds,B, and τ-lepton. These constraints provide complementary and additional information to the one obtained from the neutrinoless double-β (0νββ) decay. As expected, the bounds on electron–electron short-range couplings are the only ones that are strongly constrained by the 0νββ decay. Although weaker, LNV effective couplings with different flavors are not accessible to 0νββ decay and these can be probe by the |ΔL|=2 processes in consideration. © 2016 The AuthorItem Exploring GeV-scale Majorana neutrinos in lepton-number-violating Λb0 baryon decays(American Physical Society, 2017-07-28) Mejía Guisao, Jhovanny; Milanés, Diego; Quintero, Néstor; Ruiz Álvarez, José D.In this work, the lepton-number-violating processes in | Δ L | = 2 decays of Λ 0 b baryon, Λ 0 b → p π + μ − μ − and Λ 0 b → Λ + c π + μ − μ − , are investigated for the first time, via an intermediate on-shell Majorana neutrino N with a mass in the GeV scale. We explore the experimental sensitivity of these dimuon channels at the LHCb and CMS experiments, in which heavy neutrino lifetimes in the accessible ranges of τ N = [ 1 , 100 , 1000 ] ps are considered. For a integrated luminosity collected of 10 and 50 fb − 1 at the LHCb and 30, 300, and 3000 fb − 1 at the CMS, we found significant sensitivity on branching fractions of the order BR ( Λ 0 b → p π + μ − μ − ) ≲ O ( 10 − 9 – 10 − 8 ) and BR ( Λ 0 b → Λ + c π + μ − μ − ) ≲ O ( 10 − 8 – 10 − 7 ) . Exclusion regions on the parameter space ( m N , | V μ N | 2 ) associated with the heavy neutrino are presented and compared with those from K − → π + μ − μ − (NA48/2) and B − → π + μ − μ − (LHCb) as well as by different search strategies such as NA3, CHARMII, NuTeV, Belle, and DELPHI.Item Lepton-number violation in Bs meson decays induced by an on-shell Majorana neutrino(American Physical Society, 2018-04-01) Mejía-Guisao, Jhovanny; Milanés, Diego A.; Quintero, Néstor; Ruiz-Álvarez, José DavidLepton-number violation can be induced by the exchange of an on-shell Majorana neutrino N in semileptonic |ΔL|=2 decays of the Bs meson, Bs0→P-π-μ+μ+ with P=K,Ds. We investigate the production of such a heavy sterile neutrino through these four-body μ+μ+ channels and explore the sensitivity that can be reached at the LHCb and CMS experiments. For heavy neutrino lifetimes of τN=[1,100,1000] ps and integrated luminosities collected of 10 and 50 fb-1 at the LHCb and 30, 300, and 3000 fb-1 at the CMS, we find a significant sensitivity on branching fractions of the orders BR(Bs0→K-π-μ+μ+) O(10-9-10-8) and BR(Bs0→Ds-π-μ+μ+) O(10-8-10-7). In the kinematically allowed mass ranges of mN[0.25,4.77] GeV and mN[0.25,3.29] GeV, respectively, we exclude regions on the parameter space (mN,|VμN|2) associated with the heavy neutrino, which could slightly improve the limits from B-→π+μ-μ- (LHCb). © 2018 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Item Search for lepton-number-violating signals in the charm sector(American Physical Society, 2018-11-01) Milanés, Diego A.; Quintero, NéstorWe explore signals of lepton-number-violation in the charm physics sector. We study the four-body |ΔL|=2 decays of the D0 meson, D0→P-π-μ+μ+ (P=π, K) as an alternative evidence of the Majorana nature of neutrinos. We carry out an exploratory study on the potential sensitivity that LHCb experiment could achieve for these |ΔL|=2 processes. We show that for a long term expected integrated luminosity of 300 fb-1, a signal significance of branching ratios of the order O(10-9) might be accessible, allowing to improve the experimental bounds obtained by the E791 experiment. Limits on the parameter space of a heavy sterile neutrino that could be obtained from their experimental search are discussed as well. © 2018 authors. Published by the American Physical Society.Item Singlet vector leptoquark model facing recent LHCb and BABAR measurements(Elsevier B.V., 2023) García Duque, Cristian H.; Cabarcas J. M.; Muñoz J. H.; Quintero, Néstor; Rojas, EduardoVery recently the LHCb experiment released the first measurement of the ratio R(c) = BR(b → cτ ν¯τ )/BR(b → cμν¯μ). Moreover, the BABAR experiment reported a new result of the leptonic decay ratio of Upsilon meson ϒ(3S), namely, Rϒ(3S) = BR(ϒ(3S) → τ+τ−)/BR(ϒ(3S) → μ+μ−). Both measurements are below their corresponding Standard Model predictions (deficit), deviating by ∼ 1.1σ and ∼ 1.8σ, respectively. In addition, the LHCb recently presented the first search of the lepton flavor violating decay B0 → K∗0μ±τ∓. Motivated by these new data, in this work we study their impact on the phenomenology of the singlet vector leptoquark (U1) model addressing the hints of lepton flavor universality violation in the semileptonic decays of B mesons (B meson anomalies), by carrying out a global fit analysis. In general, we found that a minimal version of the U1 model with a mass of 2 TeV can successfully explain the B meson anomalies, while being compatible with all other flavor observables and LHC bounds.