Variational method with staggered fermions

TL;DR

This paper extends the variational method to staggered fermions in lattice QCD, enabling eigenstate determination and parity-partner separation, demonstrated through charmed-antistrange meson spectrum calculations.

Contribution

It introduces a simple modification allowing the variational method to be applied to staggered fermions, which lack a conventional transfer matrix.

Findings

Successful application to charmed-antistrange meson spectrum

Method enables separation of parity-partner states

Extension broadens variational method's applicability

Abstract

The variational method is used widely for determining eigenstates of the QCD hamiltonian for actions with a conventional transfer matrix, e.g., actions with improved Wilson fermions. An alternative lattice fermion formalism, staggered fermions, does not have a conventional single-time-step transfer matrix. Nonetheless, with a simple modification, the variational method can also be applied to that formalism. In some cases the method also provides a mechanism for separating the commonly paired parity-partner states. We discuss the extension to staggered fermions and illustrate it by applying it to the calculation of the spectrum of charmed-antistrange mesons consisting of a clover charm quark and a staggered strange antiquark.