How far can you go ? Surprises and pitfalls in three-flavour chiral extrapolations

TL;DR

This paper explores the complexities and potential pitfalls of three-flavour chiral extrapolations in QCD, emphasizing the impact of strange sea quarks on chiral symmetry breaking and lattice simulation results.

Contribution

It highlights the possible differences between two- and three-flavour chiral limits and discusses how lattice simulations can reveal these effects.

Findings

Large differences in chiral limits due to strange quark effects

Potential convergence issues in three-flavour chiral series

Lattice simulations can detect quark-mass dependence effects

Abstract

The presence of strange sea quark pairs may have a significant impact of the pattern of chiral symmetry breaking : in particular large differences can occur between the chiral limits of two and three massless flavours (i.e., whether $m_s$ is kept at its physical value or sent to zero). We recall some indications of such a scenario in QCD, in relation with the peculiar dynamics of the scalar sector. We explain how this could affect the convergence of three-flavour chiral series, commonly used to extrapolate the results of lattice simulations. Finally, we indicate how lattice simulations with three dynamical flavours could unveil such an effect through the quark-mass dependence of light meson masses and decay constants.