Optimizing creation operators for charmonium spectroscopy on the lattice

Abstract

Smearing the bare quantum fields in lattice calculations before applying composite hadron creation operators has a long record of substantially improving overlaps onto low-lying energy eigenstates. A technique called distillation which defines smearing for quark fields as a low-rank linear projection operator into a small vector space of smooth gauge-covariant fields has proven to be both effective and versatile in hadron spectroscopy calculations albeit with significant computational cost. In this paper, more general operators in this space of smooth fields are introduced and optimized, which enhances the performance of the method when tested on systems of heavy quark-antiquark pairs close to the charmonium energy scale.