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

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

## Estimating Excited-States Contamination of $B \to \pi$ Form Factors Using Heavy Meson Chiral Perturbation Theory

Aug 8, 2022, 3:20 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

Alexander Broll (HU Berlin)

### Description

Combining experimental input, perturbative calculations, and form factors computed in lattice QCD simulations, it is possible to deduce $|V_{ub}|$ from semileptonic decays of B mesons. But the results of the form factors are contaminated by excited-states, which may lead to noticeable systematic errors in the desired CKM matrix element.
This talk presents our recent computations of the dominant $B\pi$ excited-states contamination in $B \to \pi$ form factors in Heavy Meson Chiral Perturbation Theory. The results were obtained in the static limit and to NLO in the chiral expansion and include new, to date unknown, low energy constants. Depending on their value, the effects for lattice simulations can be considerable.

### Primary authors

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