${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay in scalar and vector leptoquark scenarios

Abstract

It has been shown that the anomalies observed in $\bar{B}\to D^{(\ast )}\tau {\bar{\nu }}_{\tau }$ and $\bar{B}\to \bar{K}{\ell }^{+}{\ell }^{-}$ decays can be resolved by adding a single scalar or vector leptoquark to the Standard Model, while constraints from other precision measurements in the flavour sector can be satisfied without fine-tuning. To further explore these two interesting scenarios, in this paper, we study their effects in the semi-leptonic ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay. Using the best-fit solutions for the operator coefficients allowed by the current data of mesonic decays, we find that (i) the two scenarios give similar amounts of enhancements to the branching fraction $\mathcal{B}({\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau })$ and the ratio $R_{{\Lambda }_c}=\mathcal{B}({\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau })/\mathcal{B}({\Lambda }_b\to {\Lambda }_c\ell {\bar{\nu }}_{\ell })$, (ii) the two best-fit solutions in each of these two scenarios are also indistinguishable from each other, (iii) both scenarios give nearly the same predictions as those of the Standard Model for the longitudinal polarizations of ${\Lambda }_c$ and $\tau$ as well as the lepton-side forward-backward asymmetry. With future measurements of these observables in ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay at the LHCb, the two leptoquark scenarios could be further tested, and even differentiated from the other NP explanations for the $R_{D^{(\ast )}}$ anomalies. We also discuss the feasibility for the measurements of these observables at the LHC and the future $e^{+}{e}^{-}$ colliders.

29 pages, 4 tables and 2 figures; More references and the feasibility for the measurements of the observables in these decays at the LHC and the future $e^{+}{e}^{-}$ colliders added, final version published in the journal

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Cited by in corpus (20)

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• Probing new physics in semileptonic ${\Lambda }_b$ decays
• Global fit to $b\to c\tau \nu$ anomalies as of Spring 2024
• Phenomenology of $b\to c\tau \bar{\nu }$ decays in a scalar leptoquark model
• Review of Semileptonic $B$ Anomalies
• The measurable angular distribution of ${\Lambda }_b^0\to {\Lambda }_c^{+}(\to {\Lambda }^0{\pi }^{+}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decay
• Amplitude analysis of the ${\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+}$ decay and ${\Lambda }_c^{+}$ baryon polarization measurement in semileptonic beauty hadron decays
• Form Factor Counting and HQET Matching for New Physics in ${\Lambda }_b\to {\Lambda }_c^{\ast }l\nu$
• On sum rules for semi-leptonic $b\to c$ and $b\to u$ decays
• $b\to c\tau \bar{\nu }$ decays in supersymmetry with $R$-parity violation
• New physics effects on ${\Lambda }_b\to {\Lambda }_c^{\ast }\tau {\bar{\nu }}_{\tau }$ decays
• Time-reversal asymmetries in ${\Lambda }_b$ semileptonic decays
• New physics in the angular distribution of $B_c^{-}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decay
• Baryonic heavy-to-light form factors induced by tensor current in light-front approach
• An Imperative study of the angular observables in ${\Lambda }_b\to {\Lambda }_c^{+}(\to \Lambda {\pi }^{+}){\ell }^{-}{\bar{\nu }}_{\ell }$ decay and probing the footprint of new physics
• Visible energy and angular distributions of the charged particle from the $\tau -$decay in $b\to c\tau (\mu {\bar{\nu }}_{\mu }{\nu }_{\tau },\pi {\nu }_{\tau },\rho {\nu }_{\tau }){\bar{\nu }}_{\tau }$ reactions
• Addressing the $R_{\tau /\mu ,e}\left(D^{(\ast )}\right)$ puzzle through New Physics four-fermion operators and their impact on ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay
• Predictions for ${\Lambda }_b\to {\Lambda }_c\tau \bar{\nu }$ in BLSSM with Inverse seesaw