Theory of B -> K(*)l+l- decays at high q^2: OPE and quark-hadron duality

TL;DR

This paper develops a systematic operator product expansion framework for analyzing B -> K(*)l+l- decays at high q^2, providing new insights into nonperturbative effects and quark-hadron duality violations.

Contribution

It introduces a simplified operator basis, explicitly calculates subleading matrix elements, and quantitatively estimates duality violation in high q^2 B decays.

Findings

Explicit calculation of subleading operator matrix elements.

Quantitative estimate of quark-hadron duality violation.

Connection between OPE validity and duality in a toy model.

Abstract

We develop a systematic framework for exclusive rare B decays of the type B -> K(*)l+l- at large dilepton invariant mass q^2. It is based on an operator product expansion (OPE) for the required matrix elements of the nonleptonic weak Hamiltonian in this kinematic regime. Our treatment differs from previous work by a simplified operator basis, the explicit calculation of matrix elements of subleading operators, and by a quantitative estimate of duality violation. The latter point is discussed in detail, including the connection with the existence of an OPE and an illustration within a simple toy model.