New physics in b→sμ+μ− : Distinguishing models through C

Abstract

At present, there are several measurements of B decays that exhibit discrepancies with the predictions of the SM, and suggest the presence of new physics (NP) in b → sµ + µ − transitions. Many NP models have been proposed as explanations. These involve the tree-level exchange of a leptoquark (LQ) or a flavor-changing Z boson. In this paper we examine whether it is possible to distinguish the various models via CP-violating effects in B → K ( * ) µ + µ − . Using fits to the data, we find the following results. Of all possible LQ models, only three can explain the data, and these are all equivalent as far as b → sµ + µ − processes are concerned. In this single LQ model, the weak phase of the coupling can be large, leading to some sizeable CP asymmetries in B → K ( * ) µ + µ − . There is a spectrum of Z models; the key parameter is g µµ L , which describes the strength of the Z coupling tos mixing are stringent (weak), leading to a small (large) value of the NP weak phase, and corresponding small (large) CP asymmetries. We therefore find that the measurement of CP-violating asymmetries in B → K ( * ) µ + µ − can indeed distinguish among NP b → sµ + µ − models.

New physics in b→sμ+μ− after the measurement of Alok1, Bhattacharya2, Datta3 et al. 2017Phys. Rev. DSelf Cite16541970View full textAdd to dashboardCite

“…However, it was shown in Ref. [73] that the present constraints from B → K ( * ) νν are far weaker than those from b → sµ + µ − processes, so that the current b → sνν data cannot be used to distinguish the three LQ models. (This said, this conclusion can be evaded if the LQs couple to other leptons, see Ref.…”

“…[73] for definitions) are measured in various q 2 bins. The experimental measurements are given in Tables VI and VII in the Appendix.…”

“…The one thing to keep in mind is that Ref. [73] considered a complex g bs L , while here it is taken to be real.…”

“…[73]. It was found that, of the ten LQ models that couple to SM particles through dimension ≤ 4 operators, only three can explain the b → sµ + µ − data.…”

The B → πK puzzle revisited

“…The formalism is described in ref. [49], to which we refer the reader for details. Briefly, in the presence of SM and NP contributions, B 0 s -B 0 s mixing is due to the operator 6) where…”