Precise predictions for ${\Lambda }_b\to {\Lambda }_c$ semileptonic decays

Abstract

We calculate the ${\Lambda }_b\to {\Lambda }_c\ell \nu$ form factors and decay rates for all possible $b\to c\ell \bar{\nu }$ four-Fermi interactions beyond the Standard Model, including nonzero charged lepton masses and terms up to order ${\alpha }_s{\Lambda }_{\text{QCD}}/m_{c,b}$ and ${\Lambda }_{\text{QCD}}^2/m_c^2$ in the heavy quark effective theory. At this order, we obtain model independent predictions for semileptonic ${\Lambda }_b\to {\Lambda }_c$ decays in terms of only two unknown sub-subleading Isgur-Wise functions, which can be determined from fitting LHCb and lattice QCD data. We thus obtain model independent results for ${\Lambda }_b\to {\Lambda }_c\ell \bar{\nu }$ decays, including predictions for the ratio $R({\Lambda }_c)=\mathcal{B}({\Lambda }_b\to {\Lambda }_c\tau \bar{\nu })/\mathcal{B}({\Lambda }_b\to {\Lambda }_c\mu \bar{\nu })$ in the presence of new physics, that are more precise than prior results in the literature, and systematically improvable with better data on the decays with $\mu$ (or $e$) in the final state. We also explore tests of factorization in ${\Lambda }_b\to {\Lambda }_c\pi$ decays, and emphasize the importance of measuring at LHCb the double differential rate $d^2\Gamma ({\Lambda }_b\to {\Lambda }_c\ell \bar{\nu })/(d{q}^{2}d\cos \theta )$, in addition to the $q^2$ spectrum.

30 pages, 7 figures, 1 table

References in corpus (10)

• $R(D^{\ast })$, $|V_{cb}|$, and the Heavy Quark Symmetry relations between form factors
• Extraction of $|V_{cb}|$ from $B\to D^{(\ast )}\ell {\nu }_{\ell }$ and the Standard Model predictions of $R(D^{(\ast )})$
• The semileptonic decay Lambda_b -> Lambda_c + tau(-) + antinu_tau in the covariant confined quark model
• ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ Decay in the Standard Model and with New Physics
• New Physics in the Visible Final States of $B\to D^{(\ast )}\tau \nu$
• Study of the kinematic dependences of ${\Lambda }_b^0$ production in $pp$ collisions and a measurement of the ${\Lambda }_b^0\to {\Lambda }_c^{+}{\pi }^{-}$ branching fraction
• Tensions and correlations in $|V_{cb}|$ determinations
• ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay in scalar and vector leptoquark scenarios
• Extracting short distance information from b -> s l+ l- effectively
• Precise predictions for B -> Xc tau nu decay distributions

Cited by in corpus (6)

• Flavor Anomalies in Heavy Quark Decays
• Investigation of Effects of New Physics in ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ Decay
• The measurable angular distribution of ${\Lambda }_b^0\to {\Lambda }_c^{+}(\to {\Lambda }^0{\pi }^{+}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decay
• 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
• New physics effects on ${\Lambda }_b\to {\Lambda }_c^{\ast }\tau {\bar{\nu }}_{\tau }$ decays
• b-baryon semi-tauonic decays in the Standard Model