Towards a Precision Determination of alpha in B \to pi pi Decays

Abstract

An assumption of isospin symmetry permits the determination of sin(2 alpha) from the experimental study of B\to pi pi decays. Isospin, however, is merely an approximate symmetry; its breaking predicates a theoretical systematical error sigma_α^{\rm IB} in the extraction of alpha. We focus on the impact of π^0-η,η^\prime mixing, as well as the manner in which it is amenable to empirical constraint, and determine that σ_α^{\rm IB} can potentially be controlled to {\cal O}(1^\circ).