excited-state contamination in lattice calculations of B-meson correlation functions

Oliver Bär; Alexander Broll; Rainer Sommer

doi:10.1140/epjc/s10052-023-11906-z

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 757
https://doi.org/10.1140/epjc/s10052-023-11906-z

Regular Article - Theoretical Physics

$B π$ $B\pi$ excited-state contamination in lattice calculations of B-meson correlation functions

Oliver Bär¹^a, Alexander Broll¹ and Rainer Sommer²

¹ Institute of Physics, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489, Berlin, Germany
² NIC Research Group, Deutsches Elektronen Synchrotron (DESY), Platanenallee 6, 15738, Zeuthen, Germany

^a obaer@physik.hu-berlin.de

Received: 12 June 2023
Accepted: 4 August 2023
Published online: 29 August 2023

Abstract

Multi-particle states with additional pions are expected to result in a difficult-to-control excited-state contamination in lattice simulations. We show that heavy meson chiral perturbation theory can be employed to estimate the contamination due to two-particle $B π$ $B\pi$ states in various B-meson observables, like the B-meson decay constant and the $B^{*} B π$ $B^*B\pi$ coupling. We work in the static limit and to next-to-leading order in the chiral expansion, i.e. including $O (p) .$ $\textrm{O}(p).$ The $B π$ $B\pi$ states are found to typically lead to an overestimation of the observables at the few percent level. We determine two of the LECs from $B \to π$ $B\rightarrow \pi$ form factor computations of the KEK group (Colquhoun et al. in Phys. Rev. D 106:054502, 2022) and discuss ways to determine the others. In particular, one LEC which is associated with smeared interpolating fields seems to be easily accessible and thus opens up a way to systematically study the effect of smearing on excited-state effects.

© The Author(s) 2023

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