How large can the branching ratio ofBs→τ+τ−be?

Abstract

Motivated by the large like-sign dimuon charge asymmetry observed recently, whose explanation would require an enhanced decay rate of Bs → τ + τ − , we explore how large a branching ratio of this decay mode is allowed by the present constraints. We use bounds from the lifetimes of B d and Bs, constraints from the branching ratios of related b → sτ + τ − modes, as well as measurements of the mass difference, width difference and CP-violating phase in the Bs-Bs system. Using an effective field theory approach, we show that a branching ratio as high as 15% may be allowed while being consistent with the above constraints. The measurement of this decay, therefore, may be within the reach of current experiments, and can point toward a specific class of new physics models. We also explore the possible enhancement of this decay in models with leptoquarks and Z ′ , and find that in the latter case the branching ratio may be as much as 5%, which can alleviate the dimuon anomaly to some extent.

The inclusive decay revisited

“…One promising candidate was the decay B s → τ + τ − , which was investigated e.g. in [53,54,55,56,57,58]. Having stronger experimental bounds on this channel would be very helpful, even if the significance of the deviation in the dimuon asymmetry went down recently [59].…”

EFFECT OF BOTH Z AND Z′-MEDIATED FLAVOR-CHANGING NEUTRAL CURRENTS ON Bs →τ+τ- DECAY

“…We observe that as the mass of Z′ boson increases, the contribution of Z′ boson to the branching ratio decreases. For a light Z′ boson with mass = 100 GeV, we find an enhancement up to [20,21] could help to explain the recently observed like-sign dimuon charge asymmetry to some extent. In order to fully reconcile the D0 result, some contributions from NP in the d B sector are needed [79,80].…”

“…From Eq. (4), it is clear that the study of [20,21] would explain the observed like-sign dimuon charge asymmetry in the B system. In this paper, we take the mass of Z′ boson in the range of 100 GeV -2 TeV for our calculations.…”

“…gives a better understanding of new physics involved in decay [20,21] would explain the observed like-sign dimuon charge asymmetry in the B system. In this paper, we study…”

Theory status of b\rightarrow s l^+ l^- decays and their combined analysis

“…They do not allow for larger modifications of the decay width difference ∆Γ s of the B s -meson in the SM than 35% assuming single operator dominance. The interplay of several operators allows for larger effects [48].…”