# The 39th International Symposium on Lattice Field Theory (Lattice 2022)

Aug 8 – 13, 2022
Hörsaalzentrum Poppelsdorf
Europe/Berlin timezone

## $B\pi$ excited-state contamination in $B$-meson observables

Aug 8, 2022, 3:00 PM
20m
CP1-HSZ/1st-1.002 - HS6 (CP1-HSZ)

### CP1-HSZ/1st-1.002 - HS6

#### CP1-HSZ

50
Oral Presentation Weak Decays and Matrix Elements

### Speaker

Oliver Bär (Humboldt Universität zu Berlin)

### Description

Multi-particle states with additional pions are expected to result in a non-negligible excited-state contamination in lattice simulations at the physical point. We show that heavy meson chiral perturbation theory (HMChPT) can be employed to calculate the contamination due to two-particle $B\pi$ states in various $B$-meson observables like the decay constant $f_B$ and the $B^*B\pi$ coupling $g_{\pi}$. We work in the static limit and to next-to-leading order (NLO) in the chiral expansion. The $B\pi$ states are found to typically overestimate the observables at the few percent level depending on the size of two currently unknown NLO low-energy coefficients. A strategy to independently measure one of them with the 3-point function of the light axial vector current will be discussed.

### Primary authors

Alexander Broll (HU Berlin) Oliver Bär (Humboldt Universität zu Berlin) Rainer Sommer (DESY Zeuthen, Humboldt Berlin)