Probing new physics in semileptonic $$\Xi _{b}\rightarrow \Lambda (\Xi _{c})\tau ^{-}\bar{\nu }_{\tau }$$ Ξb→Λ(Ξc)τ-ν¯τ decays

• Main Authors: Jiao Zhang, Xiuyun An, Ruirui Sun, Jianfeng Su
• Format: Article
• Language: English
• Published: SpringerOpen 2019-10-01
• Series: European Physical Journal C: Particles and Fields
• Online Access: http://link.springer.com/article/10.1140/epjc/s10052-019-7373-4

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 $$\Xi _{b}\rightarrow \Lambda (\Xi _{c})\tau ^{-}\bar{\nu }_{\tau }$$ Ξb→Λ(Ξc)τ-ν¯τ which are mediated by $$b\rightarrow u(c)\tau ^{-}\bar{\nu }_{\tau }$$ b→u(c)τ-ν¯τ 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 $$Br(B_{c}^+\rightarrow \tau ^+ \nu _{\tau })$$ Br(Bc+→τ+ντ) , $$R^{l}_{\pi }$$ Rπl , $$R_{D^{(*)}}$$ RD(∗) , $$R_{J/\psi }$$ RJ/ψ and $$F_{L}^{D^{*}}$$ FLD∗ anomalies and investigate their New Physics effects on several observables relative to the $$\Xi _{b}\rightarrow \Lambda (\Xi _{c})\tau ^{-}\bar{\nu }_{\tau }$$ Ξb→Λ(Ξc)τ-ν¯τ decays. We mention the differential branching fraction $${\text {d}}Br/{\text {d}}q^2$$ dBr/dq2 , the ratio of branching fractions $$R(q^2)$$ R(q2) , the lepton-side forward–backward asymmetry $$A_{FB}(q^2)$$ AFB(q2) , the longitudinal polarization $$P_{L}^{\Lambda (\Xi _{c})}(q^2)$$ PLΛ(Ξc)(q2) of the daughter baryons $$\Lambda (\Xi _{c})$$ Λ(Ξc) and $$P_{L}^{\tau }(q^2)$$ PLτ(q2) of the $$\tau $$ τ lepton, and the convexity parameter $$C_{F}(q^2)$$ CF(q2) .