2013/03/31 by Andrzej J. Buras, Robert Fleischer, Jennifer Girrbach +1 · 101 citations
Mathematics · Physics and Astronomy · #Asymmetry #Branching (polymer chemistry) #Branching fraction #CP violation #Gauge (firearms) #Geometry #High-Energy Particle Collisions Research #Mathematics #Meson #Nuclear physics #Observable #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Pseudoscalar #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Scalar (mathematics) #Standard Model (mathematical formulation) #hep-ex #hep-lat #hep-ph
paper · pdf · doi:10.1007/jhep07(2013)077
published in Journal of High Energy Physics 2013(7) (Springer Nature) · 39 pages, 11 figures; added rare decay constraints, a reference and clarifying comments, and made minor corrections to numerics; to appear in JHEP
arxiv created 2013/06/06 · openalex publication_date 2013/07/01 · arxiv updated 2014/12/19 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
The Bs to mu+ mu- decay plays an outstanding role in tests of the Standard Model and physics beyond it. The LHCb collaboration has recently reported the first evidence for this decay at the 3.5 sigma level, with a branching ratio in the ballpark of the Standard Model prediction. Thanks to the recently established sizable decay width difference of the Bs system, another observable, AmumuDeltaGamma, is available, which can be extracted from the time-dependent untagged Bs to mu+ mu- rate. If tagging information is available, a CP-violating asymmetry, Smumu, can also be determined. These two observables exhibit sensitivity to New Physics that is complementary to the branching ratio. We define and analyse scenarios in which these quantities allow us to discriminate between model-independent effective operators and their CP-violating phases. In this context we classify a selection of popular New Physics models into the considered scenarios. Furthermore, we consider specific models with tree-level FCNCs mediated by a heavy neutral gauge boson, pseudoscalar or scalar, finding striking differences in the predictions of these scenarios for the observables considered and the correlations among them. We update the Standard Model prediction for the time-integrated branching ratio taking the subtle decay width difference effects into account. We find (3.56 +/- 0.18) x 10-9, and discuss the error budget.