The $\Lambda_b \to \Lambda\ (\to p \pi^-)\mu^+\mu^-$ decay in the $\text{RS}_{c}$ model

TL;DR

This paper investigates the decay process mbda_b mbda   in the Randall-Sundrum model with custodial protection, analyzing how new physics could affect observable decay parameters within experimental constraints.

Contribution

It provides a detailed analysis of how the mbda_b decay observables are affected by the RS_c model, considering current experimental constraints and calculating deviations in Wilson coefficients.

Findings

Wilson coefficients show slight deviations from Standard Model values

Current constraints prevent explaining LHCb mbda_b decay discrepancies

Analysis of decay observables across different di-muon mass bins

Abstract

We study the four body decay $\Lambda_b \rightarrow \Lambda ( \rightarrow p \pi^-) \mu^{+} \mu^{-}$ in the Randall-Sundrum model with custodial protection $(\text{RS}_c)$. By considering the constraints coming from the direct searches of the lightest Kaluza-Klein (KK) excitation of the gluon, electroweak precision tests, the measurements of the Higgs signal strengths at the LHC and from $\Delta F=2$ flavor observables, we perform a scan of the parameter space of the $\text{RS}_c$ model and obtain the maximum allowed deviations of the Wilson coefficients $\Delta C^{(\prime)}_{7,\; 9,\; 10}$ for different values of the lightest KK gluon mass $M_{g^{(1)}}$. Later, their implications on the observables such as differential branching fraction, longitudinal polarization of the daughter baryon $\Lambda$, forward-backward asymmetry with respect to leptonic, hadronic and combined lepton-hadron angles are discussed where we present the analysis of these observables in different bins of di-muon invariant mass squared $s\;(= q^2)$. It is observed that with the current constraints the Wilson coefficients in $\text{RS}_c$ model show slight deviations from their Standard Model values and hence can not accommodate the discrepancies between the Standard Model calculations of various observables and the LHCb measurements in $\Lambda_b$ decays.