Study of the exclusive $b \to u \ell^- \bar{\nu}_{\ell}$ decays in the MSSM with and without R-parity violation

TL;DR

This paper investigates how the MSSM with and without R-parity violation affects exclusive $b o u \, ext{lepton} \, ar{ u}$ decays, providing bounds on new physics parameters and predicting observable effects in future experiments.

Contribution

It derives new bounds on MSSM parameters from experimental data and predicts measurable effects of charged Higgs and R-parity violation on decay observables.

Findings

Charged Higgs and R-parity violating effects can be large and measurable.

New upper bounds on new physics parameters are established.

Predictions include modifications to branching ratios and asymmetries.

Abstract

We study the exclusive $b \to u \ell^- \bar{\nu}_{\ell} (\ell=\tau,\mu,e)$ decays in the MSSM with and without R-parity violation. From the experimental measurements of branching ratios $\mathcal{B}(B^-_u \to \tau^- \bar{\nu}_{\tau})$, $\mathcal{B}(B^-_u \to M'^0 \ell'^- \bar{\nu}_{\ell'})$ and $\mathcal{B}(\bar{B}^0_d \to M'^+ \ell'^- \bar{\nu}_{\ell'})$ $(\ell'=\mu,e, M'=\pi,\rho)$, we derive new upper bounds on the relevant new physics parameters within the decays. Using the constrained new physics parameter spaces, we predict the charged Higgs effects and the R-parity violating effects on the branching ratios, the normalized forward-backward asymmetries of charged leptons, and the ratios of longitudinal to transverse polarization of the vector mesons, which have not been measured or have not been well measured yet. We find that the charged Higgs effects and the R-parity violating effects could be large and measurable in some cases. Our results could be used to probe new physics effects in the leptonic decays as well as the semileptonic decays, and will correlate with searches for direct supersymmetric signals in future experiments.