Determination of the weak phase gamma=arg(V_ub^*)

TL;DR

This paper reviews methods to determine the weak phase gamma in B meson decays, emphasizing model-independent measurements from B to pi K decays and their potential to probe new physics beyond the Standard Model.

Contribution

It provides a comprehensive review of strategies for extracting gamma with controlled uncertainties, highlighting the role of B to pi K decays and discussing alternative approaches.

Findings

B to pi K decay rates offer model-independent gamma constraints.

Hadronic uncertainties are suppressed and mainly involve nonfactorizable effects.

These decays can also serve as probes for physics beyond the Standard Model.

Abstract

Various strategies for extracting or constraining the weak phase gamma with controlled theoretical uncertainties are reviewed. Measurements of the rates for the hadronic decays B^+- -> pi K provide largely model-independent information on gamma. Hadronic uncertainties enter only at the level of nonfactorizable contributions to the decay amplitudes that are power-suppressed in Lambda/m_b and, simultaneously, violate SU(3) flavor symmetry or are doubly Cabibbo suppressed. In addition, these decays have a rich potential for probing physics beyond the Standard Model. Alternative proposals for learning gamma are also discussed briefly.