Searching for New Physics with bbar -> sbar Bs -> V_1 V_2 Penguin Decays

TL;DR

This paper develops a comprehensive angular analysis method for Bs -> V_1 V_2 decays, focusing on penguin processes, to identify potential signs of new physics through CP violation measurements.

Contribution

It introduces the most general six-helicity angular analysis for Bs decays to vector mesons, including a detailed decay amplitude and comparison with existing analyses, to enhance new physics searches.

Findings

Identifies numerous CP-violating observables in Bs -> K*0 Kbar*0 decays.

Shows that untagged data can still reveal CP violation.

Provides a framework to detect new physics without full data fitting.

Abstract

We present the most general (six-helicity) angular analysis of Bs -> V_1 (-> P_1P'_1) V_2 (-> P_2P'_2) (V_i is a vector meson, and P_i, P'_i are pseudoscalars). We focus on final states accessible to both Bs and Bsbar -- these are mainly bbar -> sbar penguin decays. We also derive the most general decay amplitude, and discuss the differences between it and that used by LHCb in its analysis of Bs -> phi phi. In the standard model, all CP violation is predicted to be small, so that the simple measurement of a sizeable CP-violating observable indicates the presence of new physics. A full fit to the data is not necessary. By determining which of the CP-violating observables are nonzero, one can learn about the structure of the underlying NP. Finally, we apply the angular analysis to Bs -> K^{*0} Kbar^{*0}, and show that there are numerous CP-violating observables that remain in the untagged data sample.