Non-minimal UED confronts $B_{s}\rightarrow\mu^{+}\mu^{-}$

TL;DR

This paper investigates how non-minimal Universal Extra Dimensional models, with boundary localized terms, affect the decay rates of B mesons to muons, providing new constraints on the model parameters from experimental data.

Contribution

It estimates the Kaluza-Klein contributions to B meson decay rates in non-minimal UED and compares these with experimental data to constrain the model's parameter space.

Findings

Lower limit on R^{-1} can reach up to 800 GeV based on B_s decay data.

The analysis rules out new parameter regions beyond electroweak bounds.

The derived R^{-1} limit (454 GeV) is less restrictive than relic density or Higgs decay constraints.

Abstract

Addition of boundary localised kinetic and Yukawa terms to the action of a 5-dimensional Standard Model would non-trivially modify the Kaluza-Klein spectra and some of the interactions among the Kaluza-Klein excitations compared to the minimal version of this model, in which, these boundary terms are not present. In the minimal version of this framework known as Universal Extra Dimensional model, special assumptions are made about these unknown, beyond the cut-off contributions to restrict the number of unknown parameters of the theory to a minimal. We estimate the contribution of Kaluza-Klein modes to the branching ratios of $B_{s(d)}\rightarrow\mu^{+}\mu^{-}$ in the framework of non-minimal Universal Extra Dimensional, at one loop level. The results have been compared to the experimental data to constrain the parameters of this model. From the measured decay branching ratio of $B_s \rightarrow \mu^+ \mu^-$ (depending on the values of boundary localised parameters) lower limit on $R^{-1}$ can be as high as 800 GeV. We have briefly reviewed the bounds on nmUED parameter space coming from electroweak precision observables. The present analysis ($B_s \rightarrow \mu^+ \mu^-$) has ruled out new regions of parameter space in comparison to the analysis of electroweak data. We have revisited the bound on $R^{-1}$ in Universal Extra Dimensional model, which came out to be 454 GeV. This limit on $R^{-1}$ in Universal Extra Dimensional framework is not as competitive as the limits derived from the consideration of relic density or Standard Model Higgs boson production and decay to $W^+ W^-$. Unfortunately, $B_{d}\rightarrow\mu^{+}\mu^{-}$ decay branching ratio would not set any significant limit on $R^{-1}$ in a minimal or non-minimal Universal Extra Dimensional model.