CP Violation in Leptonic Rare $B^0_s$ Decays as a Probe of New Physics

TL;DR

This paper discusses how measuring CP violation in the rare decay $B^0_s o\mu^+\mu^-$ can reveal new physics beyond the Standard Model, emphasizing the importance of specific observables and future collider upgrades.

Contribution

It highlights the significance of CP-violating observables in $B^0_s o\mu^+\mu^-$ decays as probes for new physics, especially in the context of future collider experiments.

Findings

CP-violating observable ${ m \\cal S}_{ m \\mu\\mu}$ is crucial for new physics detection.

Measurement of $\\mathcal{A}^{\\mu\\mu}_{\\Delta \Gamma_s}$ can reveal scalar contributions.

Future LHC upgrades can enhance sensitivity to CP violation in these decays.

Abstract

The decay $B^0_s\to\mu^+\mu^-$ is a key probe for the search of physics beyond the Standard Model. While the current measurements of the corresponding branching ratio agree with the Standard Model within the uncertainties, significant New-Physics effects may still be hiding in $B^0_s\to\mu^+\mu^-$. In order to reveal them, the observable $\mathcal{A}^{\mu\mu}_{\Delta \Gamma_s}$, which is provided by the decay width difference $\Delta\Gamma_s$ of the $B^0_s$-meson system, plays a central role. We point out that a measurement of a CP-violating observable ${\cal S}_{\rm \mu\mu}$, which is induced through interference between $B^0_s$-$\bar B^0_s$ mixing and $B_s\to\mu^+\mu^-$ decay processes, is essential to obtain the full picture, in particular to establish new scalar contributions and CP-violating phases. We illustrate these findings with future scenarios for the upgrade(s) of the LHC, exploiting also relations which emerge within an effective field theory description of the Standard Model, complemented with New Physics entering significantly beyond the electroweak scale.