${\Lambda }_b\to ({\Lambda }_c,p)\tau \nu$ decays within standard model and beyond

Abstract

Deviations from the standard model prediction have been observed in several leptonic and semileptonic $B$ meson decays to $\tau \nu$ final states mediated via $b\to u$ and $b\to c$ charged current interactions. The measured value of ratio of branching ratios $R_{\pi }^l$ of $B^{-}\to {\tau }^{-}{\nu }_{\tau }$ to $B^0\to {\pi }^{+}{ł}^{-}\nu$ decays, where $l=(e,\mu )$, is larger than the standard model prediction by more than a factor of two. Similarly, a combined excess of $3.9\sigma$ from the standard model expectation has been reported by HFAG for the values of $R_D$ and $R_{D^{\ast }}$, where $R_{D,D^{\ast }}$ represents the ratio of branching ratios of $B\to (D,D^{\ast })\tau \nu$ to corresponding $B\to (D,D^{\ast })l\nu$ decays, respectively. Very recently, hint of lepton flavor violation has been observed in the ratio of branching fractions of $B\to K{e}^{+}{e}^{-}$ to $B\to K{\mu }^{+}{\mu }^{-}$ decays as well. In this context, we employ an effective Lagrangian approach to study the decay branching fractions and the ratio of branching fractions of ${\Lambda }_b\to {\Lambda }_{c}l\nu$ and ${\Lambda }_b\to pl\nu$ decays within the standard model and beyond. We constrain the new physics parameter space using the existing experimental data on $R_D$, $R_{D^{\ast }}$, and $R_{\pi }^l$. We give predictions for various observables in the context of various new physics scenarios.

20 pages, 4 figures

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Cited by in corpus (41)

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• Global fit to $b\to c\tau \nu$ transitions
• Phenomenology of ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ using lattice QCD calculations
• Precise predictions for ${\Lambda }_b\to {\Lambda }_c$ semileptonic decays
• Semileptonic decays of ${\Lambda }_b$ baryons in the relativistic quark model
• Investigation of Effects of New Physics in ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ Decay
• Semileptonic ${\Lambda }_b\to {\Lambda }_c\ell {\bar{\nu }}_{\ell }$ Transition in Full QCD
• Probing new physics in semileptonic ${\Lambda }_b$ decays
• Inclusive semileptonic ${\Lambda }_b$ decays in the Standard Model and beyond
• Measurement of Singly Cabibbo Suppressed Decays ${\Lambda }_c^{+}\to p{\pi }^{+}{\pi }^{-}$ and ${\Lambda }_c^{+}\to p{K}^{+}{K}^{-}$
• ${\Lambda }_b\to p$ transition form factors in perturbative QCD
• Model independent analysis of $b\to (c,u)\tau \nu$ leptonic and semileptonic decays
• ${\Lambda }_b\to {\Lambda }_c^{\ast }(2595,2625){\ell }^{-}\bar{\nu }$ form factors from lattice QCD
• 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
• The role of right-handed neutrinos in $b\to c\tau (\pi {\nu }_{\tau },\rho {\nu }_{\tau },\mu {\bar{\nu }}_{\mu }{\nu }_{\tau }){\bar{\nu }}_{\tau }$ from visible final-state kinematics
• Phenomenology of ${\Xi }_b\to {\Xi }_c\tau \nu$ decays
• Probing effects of new physics in ${\Lambda }_b^0\to {\Lambda }_c^{+}{\mu }^{-}{\bar{\nu }}_{\mu }$ decays
• Implication of $R_{D^{(\ast )}}$ anomalies on semileptonic decays of ${\Sigma }_b$ and ${\Omega }_b$ baryons
• Form Factor Counting and HQET Matching for New Physics in ${\Lambda }_b\to {\Lambda }_c^{\ast }l\nu$
• Semileptonic Transition of ${\Lambda }_b$ Baryon
• ${\Lambda }_b\to p,N^{\ast }(1535)$ Form Factors from QCD Light-Cone Sum Rules
• Implication of $b\to c\tau \nu$ flavor anomalies on $B_s\to D_s^{\ast }\tau \nu$ decay observables
• Heavy baryon wave functions, Bakamjian-Thomas approach to form factors, and observables in ${\Lambda }_b\to {\Lambda }_c\left({\frac{1}{2}}^{\pm }\right)\ell \overline{\nu }$ transitions
• Detailed Study of the Decay Lambda_b --> Lambda_c tau {\bar ν}_τ
• Probing new physics in semileptonic ${\Sigma }_b$ and ${\Omega }_b$ decays
• New physics footprints in the angular distribution of $B_s\to D_s^{\ast }(\to D_s\gamma ,D_s\pi )\tau \nu$ decays
• Time-reversal asymmetries in ${\Lambda }_b$ semileptonic decays
• New physics effects on ${\Lambda }_b\to {\Lambda }_c^{\ast }\tau {\bar{\nu }}_{\tau }$ decays
• $b\to c\tau \bar{\nu }$ decays in supersymmetry with $R$-parity violation
• Measurement of the absolute branching fraction of the singly Cabibbo suppressed decay ${\Lambda }_c^{+}\to p{\eta }^{\prime }$
• Extracting maximum information from polarised baryon decays via amplitude analysis: the ${\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+}$ case
• New physics in the angular distribution of $B_c^{-}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decay
• Measurement of the absolute branching fraction of the inclusive decay ${\bar{\Lambda }}_c^{-}\to \bar{n}+X$
• b-baryon semi-tauonic decays in the Standard Model
• Searching for New Physics in Semi-Leptonic Baryon Decays
• Testing Lepton Flavor Universality at the Electron-Ion Collider
• 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
• Diagnosing New Physics with LUV and LFV B Decays
• The Angular Observables of ${\Lambda }_b\to {\Lambda }_c(\to {\Lambda }^0{\pi }^{+}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ within the Paradigm of FCCC Anomalies