Translating topological benefits in very cold lattice simulations

Abstract

Master-field simulations offer an approach to lattice QCD in which calculations are performed on a small number of large-volume gauge-field configurations. The latter is advantageous for simulations in which the global topological charge is frozen due to a very fine lattice spacing, as the effect of this on observables is suppressed by the spacetime volume. Here we make use of the recently developed Stabilised Wilson Fermions to investigate a variation of this approach in which only the temporal direction ($T$) is taken larger than in traditional calculations. As compared to a hyper-cubic lattice geometry, this has the advantage that finite-$L$ effects can be useful, e.g. for multi-hadron observables, while compared to open boundary conditions, time-translation invariance is not lost. In this proof-of-concept contribution, we study the idea of using very cold (i.e. long-$T$) lattices to topologically "defrost" observables at fine lattice spacing. We identify the scalar-scalar meson two-point correlation function as a useful probe and present first results from $N_f=3$ ensembles with time extents up to $T=2304$ and a lattice spacing of $a=0.055\,\rm{fm}$.