Albaladejo, M., Nieves, J., Oset, E., & Jido, D. (2016). Ds0*(2317) and DK scattering in B decays from BaBar and LHCb data. Eur. Phys. J. C, 76(6), 300–8pp.
Abstract: We study the experimental DK invariant mass spectra of the reactions B+ -> (D) over bar (DK+)-D-0-K-0, B-0 -> D-(DK+)-K-0 (measured by the BaBar collaboration) and B-s -> pi(+DK-)-K-0 measured by the LHCb collaboration), where an enhancement right above the threshold is seen. We show that this enhancement is due to the presence of D-s0*(2317), which is a D K bound state in the I (J(P)) = 0(0(+)) sector. We employ a unitarized amplitude with an interaction potential fixed by heavy meson chiral perturbation theory. We obtain a mass M-Ds0* = 2315(-17) (+12 +10)(-5) MeV, and we also show, by means of theWeinberg compositeness condition, that the DK component in the wave function of this state is P-DK = 70(-6 -8)(+4 +4) %, where the first (second) error is statistical (systematic).
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Sobczyk, J. E., Rocco, N., Lovato, A., & Nieves, J. (2019). Weak production of strange and charmed ground-state baryons in nuclei. Phys. Rev. C, 99(6), 065503–16pp.
Abstract: We present results for the quasielastic weak production of Delta and Sigma hyperons induced by (nu) over bar. scattering off nuclei in the kinematical region of interest for accelerator neutrino experiments. We employ realistic hole spectral functions and we describe the propagation of the hyperons in the nuclear medium by means of a Monte Carlo cascade. The latter strongly modifies the kinematics and the relative production rates of the hyperons, leading to a nonvanishing Sigma(+) cross section, to a sizable enhancement of the Lambda production and to a drastic reduction of the Sigma(0) and Sigma(-) distributions. We also compute the quasielastic weak Lambda(c) production cross section, paying special attention to estimate the uncertainties induced by the model dependence of the vacuum n -> Lambda(c) weak matrix element. In this regard, the recent BESIII measurements of the branching ratios of Lambda(c) -> Lambda l(+)nu(l) (l = e, mu) are used to benchmark the available theoretical predictions.
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Penalva, N., Hernandez, E., & Nieves, J. (2021). New physics and the tau polarization vector in b -> c tau barnutau decays. J. High Energy Phys., 06(6), 118–37pp.
Abstract: For a general H-b -> Hc tau nu <overbar></mml:mover>tau decay we analyze the role of the tau polarization vector P μin the context of lepton flavor universality violation studies. We use a general phenomenological approach that includes, in addition to the Standard Model (SM) contribution, vector, axial, scalar, pseudoscalar and tensor new physics (NP) terms which strength is governed by, complex in general, Wilson coefficients. We show that both in the laboratory frame, where the initial hadron is at rest, and in the center of mass of the two final leptons, a P -></mml:mover> component perpendicular to the plane defined by the three-momenta of the final hadron and the tau lepton is only possible for complex Wilson coefficients, being a clear signal for physics beyond the SM as well as time reversal (or CP-symmetry) violation. We make specific evaluations of the different polarization vector components for the Lambda (b) -> Lambda (c), <mml:mover accent=“true”>B<mml:mo stretchy=“true”><overbar></mml:mover>c -> eta (c), J/psi and <mml:mover accent=“true”>B<mml:mo stretchy=“true”><overbar></mml:mover> -> D-(*) semileptonic decays, and describe NP effects in the complete two-dimensional space associated with the independent kinematic variables on which the polarization vector depends. We find that the detailed study of P μhas great potential to discriminate between different NP scenarios for 0(-) -> 0(-) decays, but also for Lambda (b) -> Lambda (c) transitions. For this latter reaction, we pay special attention to corrections to the SM predictions derived from complex Wilson coefficients contributions.
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Hernandez, E., & Nieves, J. (2011). Study of the strong Sigma(b) -> Lambda(b)pi and Sigma*(b) -> Lambda(b)pi in a nonrelativistic quark model. Phys. Rev. D, 84(5), 057902–5pp.
Abstract: We present results for the strong widths corresponding to the Sigma(b) -> Lambda(b)pi and Sigma*(b) -> Lambda(b)pi decays. We apply our model from Phys. Rev. D 72, 094022 (2005), where we previously studied the corresponding transitions in the charmed sector. Our nonrelativistic constituent quark model uses wave functions that take advantage of the constraints imposed by heavy quark symmetry. The partial conservation of axial current hypothesis allows us to determine the strong vertices from an analysis of the axial current matrix elements.
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Nieves, J., & Valderrama, M. P. (2011). Deriving the existence of B(B)over-bar* bound states from the X(3872) and heavy quark symmetry. Phys. Rev. D, 84(5), 056015–21pp.
Abstract: We discuss the possibility and the description of bound states between B and (B) over bar* mesons. We argue that the existence of such a bound state can be deduced from (i) the weakly bound X(3872) state, (ii) certain assumptions about the short-range dynamics of the D (D) over bar* system and (iii) heavy quark symmetry. From these assumptions the binding energy of the possible B (B) over bar* bound states is determined, first in a theory containing only contact interactions which serves as a straightforward illustration of the method, and then the effects of including the one-pion exchange potential are discussed. In this latter case three isoscalar states are predicted: a positive and negative C-parity (3)S(1) – (3)D(1) state with a binding energy of 20 MeV and 6 MeV below threshold, respectively, and a positive C-parity (3)P(0) shallow state located almost at the B (B) over bar* threshold. However, large uncertainties are generated as a consequence of the 1/m(Q) corrections from heavy quark symmetry. Finally, the newly discovered isovector Z(b)(10610) state can be easily accommodated within the present framework by a minor modification of the short-range dynamics.
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