Testing spin-2 mediator by angular observables in $b\rightarrow s \mu^+ \mu^-$

TL;DR

This paper investigates how a hypothetical spin-2 particle could influence angular observables in rare B meson decays involving muons, potentially explaining anomalies and predicting measurable effects beyond the Standard Model.

Contribution

It introduces a model where a spin-2 mediator couples non-universally to quarks and leptons, analyzing its effects on B decay observables and constraints from existing measurements.

Findings

Spin-2 particle can alter angular observables in B decays.

Forward-backward asymmetries can reach 15%.

Other observables are minimally affected.

Abstract

We consider effects of spin-2 particle in the $b\rightarrow s \mu^+ \mu^-$ transition assuming that the spin-2 particle couples in a flavour non-universal way to $b$ and $s$ quarks and in the leptonic sector couples only to the muons, thereby only contributing to the process $b\rightarrow s \mu^+ \mu^-$. The $B_s - \bar B_s$ transition gives the strong constraint on the coupling of the spin-2 mediator and $b$ and $s$ quarks while the observed discrepancy from the SM prediction for the muon anomalous magnetic moment $ (g-2)_\mu$ serves us to constrain the $\mu$-coupling to spin-2 particle. We find that the spin-2 particle can modify the angular observables in the $B \to K \mu^+ \mu^-$ and $B \to K^* \mu^+ \mu^-$ decays and produce effects which do not exist in the SM. The generated forward-backward asymmetries in these processes can reach $15\%$, while other observables for these decays receive tiny effects.