Probing new physics in semileptonic decays

Jiao Zhang; Xiuyun An; Ruirui Sun; Jianfeng Su

doi:10.1140/epjc/s10052-019-7373-4

EPJ

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b
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d
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2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2019) 79: 863
https://doi.org/10.1140/epjc/s10052-019-7373-4

Regular Article - Theoretical Physics

Probing new physics in semileptonic $\Xi _{b}\rightarrow \Lambda (\Xi _{c})\tau ^{-}\bar{\nu }_{\tau }$ decays

Jiao Zhang^*, Xiuyun An, Ruirui Sun and Jianfeng Su

Department of Mathematics and Physics, Luoyang Institute of Science and Technology, Luoyang, 471023, China

^* e-mail: zhangjiao198746@163.com

Received: 13 June 2019
Accepted: 6 October 2019
Published online: 21 October 2019

Abstract

Recently, several observed anomalies in semileptonic B meson decays have implied hints of lepton flavor universal violation. Motivated by these inspiring results, we study the baryon decays $\Xi _{b}\rightarrow \Lambda (\Xi _{c})\tau ^{-}\bar{\nu }_{\tau }$ which are mediated by $b\rightarrow u(c)\tau ^{-}\bar{\nu }_{\tau }$ transitions at quark level in the Standard Model and different New Physics scenarios. In the framework of the extended Standard Model on assuming a general effective theory, we constrain the Wilson coefficients of the NP operators using the experimental measurement results for the $Br(B_{c}^+\rightarrow \tau ^+ \nu _{\tau })$ , $R^{l}_{\pi }$ , $R_{D^{(*)}}$ , $R_{J/\psi }$ and $F_{L}^{D^{*}}$ anomalies and investigate their New Physics effects on several observables relative to the $\Xi _{b}\rightarrow \Lambda (\Xi _{c})\tau ^{-}\bar{\nu }_{\tau }$ decays. We mention the differential branching fraction ${\text {d}}Br/{\text {d}}q^2$ , the ratio of branching fractions $$R(q^2)$$ , the lepton-side forward–backward asymmetry $A_{FB}(q^2)$ , the longitudinal polarization $P_{L}^{\Lambda (\Xi _{c})}(q^2)$ of the daughter baryons $\Lambda (\Xi _{c})$ and $P_{L}^{\tau }(q^2)$ of the $\tau$ lepton, and the convexity parameter $C_{F}(q^2)$ .