Optimized Lepton Universality Tests in $B\to V\ell \bar{\nu }$ decays

Abstract

We propose improved Lepton Flavor Universality (LFU) ratios in semileptonic $P\to V\ell \bar{\nu }$ decays, when comparing $\mu$ and $\tau$ modes, that minimize the theoretical form-factor uncertainties. These optimized ratios are obtained with simple cuts or reweighting of the dilepton mass distributions, which imply a minimum loss of signal on the rare tauonic modes while maximizing the cancellation of theoretical uncertainties among the two modes. We illustrate the usefulness of these observables in $B_c\to J/\psi$, $B_c\to \psi (2S)$, $B\to D^{\ast }$ and $B_s\to D_s^{\ast }$ transitions, showing that in all cases we can reach $\mathcal{O}(1\%)$ uncertainties on the SM predictions of the improved LFU ratios employing conservatives form-factor uncertainties.

6 pages, 2 figures. Version to appear in EPJC

References in corpus (8)

• Test of lepton universality using $B^{+}\to K^{+}{\ell }^{+}{\ell }^{-}$ decays
• On the B to D* tau nu Sensitivity to New Physics
• Exclusive semileptonic and nonleptonic decays of the Bc meson
• $R(D^{\ast })$, $|V_{cb}|$, 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 $R(D^{(\ast )})$
• New Physics effect on $B_c\to J/\psi \tau \bar{\nu }$ in relation to the $R_{D^{(\ast )}}$ anomaly
• On lepton flavour universality in semileptonic $B_c\to {\eta }_c,J/\psi$ decays
• Precision Model-Independent Bounds from Global Analysis of $b\to c\ell \nu$ Form Factors

Cited by in corpus (8)

• New Physics effects in leptonic and semileptonic decays
• Global fit to $b\to c\tau \nu$ anomalies as of Spring 2024
• Constrained second-order power corrections in HQET: $R(D^{(\ast )})$, $|V_{cb}|$, and new physics
• $B_s\to D_s^{\ast }$ Form Factors for the full $q^2$ range from Lattice QCD
• $|V_{cb}|$, Lepton Flavour Universality and $SU(3{)}_F$ symmetry breaking in $B_s\to D_s^{(\ast )}\ell {\nu }_{\ell }$ decays through unitarity and lattice QCD
• Exclusive semileptonic $B_s\to K\ell \nu$ decays on the lattice
• Form-factor-independent test of lepton universality in semileptonic heavy meson and baryon decays
• Study of angular observables in exclusive semileptonic $B_c$ decays