Optimising creation operators for charmonium spectroscopy on the lattice

TL;DR

This paper introduces optimized creation operators within a smooth field space to improve charmonium spectroscopy on the lattice, balancing computational efficiency with spectral accuracy.

Contribution

It develops and tests more general, optimized operators in the distillation framework for better charmonium state extraction on the lattice.

Findings

Enhanced overlap with low-lying states

Improved spectral resolution for charmonium

Reduced computational cost compared to standard distillation

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 optimised, which enhances the performance of the method when tested on systems of heavy quark-anti-quark pairs close to the charmonium energy scale.