New Physics in Gamma_12^s: (sbar b) (taubar tau) Operators

TL;DR

This paper investigates how new physics operators involving tau leptons could influence B_s meson mixing and decay observables, potentially explaining deviations from the Standard Model seen in recent experiments.

Contribution

It provides a model-independent analysis of non-standard effects in Gamma_12^s from (sbar b)(taubar tau) operators and compares these with specific new physics models like leptoquarks and Z' bosons.

Findings

Absorptive new physics can partially explain current experimental anomalies.

Existing constraints on these operators are relatively weak, allowing significant effects.

Explicit models like leptoquarks and Z' bosons can produce observable effects in B_s mixing.

Abstract

Measurements performed at the Tevatron of both the like-sign dimuon charge asymmetry in B_d,s-meson samples and the mixing-induced CP asymmetry in B_s -> J/psi phi depart from their standard model (SM) predictions. This could be an indication for new CP phases in Delta B = 2 transitions, preferentially in B_s-Bbar_s mixing. The experimental situation, however, remained inconclusive, as it favored values of the element Gamma_12^s of the decay matrix in the B_s-meson system that are notably different from the SM expectation, suggesting the presence of new physics in the Delta B = 1 sector as well. The very recent LHCb measurements of B_s -> J/psi phi and B_s -> J/psi f_0, which do not find any evidence for a new-physics phase in the element M_12^s of the mass matrix, point into this direction as well. In this article, we explore the potential size of non-standard effects in Gamma_12^s stemming from dimension-six operators with flavor content (sbar b) (taubar tau). We show that since the existing constraints imposed by tree- and loop-level mediated B_d,s-meson decays are quite loose, absorptive new physics of this type can in part explain the current data. Our model-independent conclusions are finally contrasted with explicit analyses of the new-physics effects in B_s-Bbar_s mixing that can arise from leptoquarks or Z' bosons.