Trojan Penguins and Isospin Violation in Hadronic B Decays

TL;DR

This paper investigates isospin-violating effects in rare B meson decays, exploring potential New Physics contributions through electroweak penguins and deriving bounds on new couplings.

Contribution

It calculates Wilson coefficients for electroweak penguin operators in various New Physics models, showing they can be comparable to QCD penguins and discusses experimental tests.

Findings

Electroweak penguin contributions can be significant in B->pi K decays.

New Physics models can produce non-suppressed Wilson coefficients.

Bounds on New Physics couplings are established from decay observables.

Abstract

Some rare hadronic decays of B mesons, such as B->pi K, are sensitive to isospin-violating contributions from physics beyond the Standard Model. Although commonly referred to as electroweak penguins, such contributions can often arise through tree-level exchanges of heavy particles, or through strong-interaction loop diagrams. The Wilson coefficients of the corresponding electroweak penguin operators are calculated in a large class of New Physics models, and in many cases are found not to be suppressed with respect to the QCD penguin coefficients. Several tests for these effects using observables in B->pi K decays are discussed, and nontrivial bounds on the couplings of the various New Physics models are derived.