Twisted mass chiral perturbation theory for 2+1+1 quark flavours

TL;DR

This paper develops a next-to-leading order twisted mass chiral perturbation theory framework for 2+1+1 quark flavors in lattice QCD, accounting for lattice artifacts and flavor mixing effects.

Contribution

It extends chiral perturbation theory to include non-degenerate s and c quarks with lattice effects up to O(a^2), providing explicit O(a)-improvement at maximal twist.

Findings

Derived meson mass formulas including lattice artifacts.

Analyzed flavor-neutral meson mixing and corrected previous results.

Confirmed O(a)-improvement at maximal twist.

Abstract

We present results for the masses of pseudoscalar mesons in twisted mass lattice QCD with a degenerate doublet of u and d quarks and a non-degenerate doublet of s and c quarks in the framework of next-to-leading order chiral perturbation theory, including lattice effects up to O(a^2). The masses depend on the two twist angles for the light and heavy sectors. For maximal twist in both sectors, O(a)-improvement is explicitly exhibited. The mixing of flavour-neutral mesons is also discussed, and results in the literature for the case of degenerate s and c quarks are corrected.