Estimating excited states contamination of $B \to \pi$ form factors using heavy meson chiral perturbation theory

TL;DR

This paper uses Heavy Meson Chiral Perturbation Theory to estimate how excited states affect the calculation of $B o \pi$ form factors, revealing potential underestimations in lattice simulations.

Contribution

It provides the first NLO chiral perturbation theory calculation of excited state contamination in $B o \pi$ form factors in the static limit.

Findings

Excited state contamination for $h_\parallel$ is a few percent.

Large negative contributions to $h_\perp$ may be underestimated.

Results inform lattice QCD simulations of $B o \pi$ decays.

Abstract

Using Heavy Meson Chiral Perturbation Theory (HMChPT), the $B^* \pi$ excited states contamination of the $B \to \pi$ vector form factors is computed to NLO in the chiral expansion and in the static limit. The results suggest that the excited states for $h_\parallel$ are of the order of a few percent whereas $h_\perp$ receives large negative contributions and thus might be significantly underestimated in lattice simulations.