Papers
Topics
Authors
Recent
Gemini 2.5 Flash
Gemini 2.5 Flash
134 tokens/sec
GPT-4o
9 tokens/sec
Gemini 2.5 Pro Pro
47 tokens/sec
o3 Pro
4 tokens/sec
GPT-4.1 Pro
38 tokens/sec
DeepSeek R1 via Azure Pro
28 tokens/sec
2000 character limit reached

Phenomenology of $b\to cτ\barν$ decays in a scalar leptoquark model (1905.01795v1)

Published 6 May 2019 in hep-ph

Abstract: During the past few years, hints of Lepton Flavour Universality (LFU) violation have been observed in $b \to c \tau \bar\nu$ and $b \to s \ell+ \ell-$ transitions. Recently, the $D*$ and $\tau$ polarization fractions $P_L{D*}$ and $P_L\tau$ in $B \to D* \tau \bar\nu$ decay have also been measured by the Belle collaboration. Motivated by these intriguing results, we revisit the $R_{D{(*)}}$ and $R_{K{(*)}}$ anomalies in a scalar leptoquark (LQ) model, in which two scalar LQs, one being $SU(2)L$ singlet and the other $SU(2)_L$ triplet, are introduced simultaneously. We consider five $b \to c \tau \bar\nu$ mediated decays, $B \to D{(*)}\tau \bar\nu$, $B_c \to \eta_c \tau \bar\nu$, $B_c \to J/\psi \tau \bar\nu$, and $\Lambda_b \to \Lambda_c \tau \bar\nu$, and focus on the LQ effects on the $q2$ distributions of the branching fractions, the LFU ratios, and the various angular observables in these decays. Under the combined constraints by the available data on $R{D{(*)}}$, $R_{J/\psi}$, $P_L\tau(D*)$, and $P_L{D*}$, we perform scans for the LQ couplings and make predictions for a number of observables. It is found numerically that both the differential branching fractions and the LFU ratios are largely enhanced by the LQ effects, with the latter being expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.

Summary

We haven't generated a summary for this paper yet.