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

Bπ excited-state contamination in B-meson observables

8 Aug 2022, 15:00

20m

CP1-HSZ/1.002 (CP1-HSZ) - HS6 (CP1-HSZ)

Oral Presentation Weak Decays and Matrix Elements 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 $B^{\ast }B\pi$ 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.

Presentation materials

lattice2022_obaer.pdf