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

Abstract

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 $$B\pi $$ B π states in various B-meson observables, like the B-meson decay constant and the $$B^*B\pi $$ B ∗ B π coupling. We work in the static limit and to next-to-leading order in the chiral expansion, i.e. including $$\textrm{O}(p).$$ O ( p ) . The $$B\pi $$ B π states are found to typically lead to an overestimation of the observables at the few percent level. We determine two of the LECs from $$B\rightarrow \pi $$ B → π 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.