Testing lepton flavour universality in semileptonic ${\Lambda }_b\to {\Lambda }_c^{\ast }$ decays

Abstract

Lepton Flavour Universality tests with semileptonic ${\Lambda }_b\to {\Lambda }_c^{\ast }$ decays are important to corroborate the present anomalies in the similar ratios $R_{D^{(\ast )}}$, and can provide complementary constraints on possible origins of these anomalies beyond the Standard Model. In this paper we provide - for the first time - all the necessary theoretical ingredients to perform and interpret measurements of $R_{{\Lambda }_c^{\ast }}$ at the LHCb experiment. For this, we revisit the heavy-quark expansion of the relevant hadronic matrix elements, and provide their expressions to order ${\alpha }_s$ and $1/m$ accuracy. Moreover, we study the sensitivity to the form factor parameters given the projected size and purity of upcoming and future LHCb datasets of ${\Lambda }_b\to {\Lambda }_c^{\ast }\mu \bar{\nu }$ decays. We demonstrate explicitly the need to perform a simultaneous fit to both ${\Lambda }_c^{\ast }$ final states. Finally, we provide projections for the uncertainty of $R_{{\Lambda }_c^{\ast }}$ based on the form factor analysis from semimuonic decays and theoretical relations based on the heavy-quark expansion.

arXiv comment27 pages, 6 figures. v2: Fixed error in subleading IW function, added supplementary information; conclusions unchanged

References in corpus (15)

• PYTHIA 6.4 Physics and Manual
• PYTHIA 6.2 Physics and Manual
• A Brief Introduction to PYTHIA 8.1
• Heavy Quark Symmetry
• Angular Distributions of B -> K ll Decays
• $R(D^{\ast })$, $|V_{cb}|$, and the Heavy Quark Symmetry relations between form factors
• Sum Rules for Heavy Flavor Transitions in the SV Limit
• Phenomenology of ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ using lattice QCD calculations
• The Baryon Isgur-Wise Function in the Large $N_c$ Limit
• $|V_{cb}|$ from OPE Sum Rules for Heavy Flavor Transitions
• B-> D* zero-recoil formfactor and the heavy quark expansion in QCD: a systematic study
• Semileptonic Lambda_b decay to excited Lambda_c baryons at order Lambda_{QCD}/m_Q
• Reconstruction of semileptonically decaying beauty hadrons produced in high energy pp collisions
• Complete O(alpha_s^2) Corrections to Zero-Recoil Sum Rules for B-->D* Transitions
• Zero-Recoil Sum Rules for ${\Lambda }_b\to {\Lambda }_c$ Form Factors

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• ${\Lambda }_b\to {\Lambda }_c^{\ast }(2595,2625){\ell }^{-}\bar{\nu }$ form factors from lattice QCD
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• Charm-baryon semileptonic decays and the strange ${\Lambda }^{\ast }$ resonances: New insights from lattice QCD
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