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arXiv · 2112.10606

Nonperturbative running of the quark mass for $N_f=3$ QCD from the chirally rotated Schr\"odinger Functional

Isabel Campos Plasencia·Mattia Dalla Brida·Giulia Maria de Divitiis·Andrew Lytle·Mauro Papinutto·Ludovica Pirelli·Anastassios Vladikas
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Abstract

We study the Renormalisation Group (RG) running of the quark mass, for $N_f=3$ QCD with Wilson fermions in a mixed action setup, with standard Schr\"odinger Functional (SF) boundary conditions for sea quarks and chirally rotated Schr\"odinger Functional ($\chi$SF) boundary conditions for valence quarks. This necessitates the tuning of the boundary factor $z_f(g_0^2)$ of the $\chi$SF valence action, in order to ensure that QCD symmetries are fully recovered in the continuum. The properties of this novel setup are monitored through the ratios $Z_S/Z_P$ and $\Sigma_S/\Sigma_P$ of the renormalisation parameters and step scaling functions of the scalar and pseudoscalar densities. Where comparison is possible, our $Z_S/Z_P$ results are found to agree with previous determinations, based on a mass ratio method arXiv:1906.03445 and Ward identities arXiv:2005.01352, arXiv:2101.10969, with Schr\"odinger Functional boundary conditions. The behaviour of $\Sigma_S/\Sigma_P$ confirms the theoretical expectations of $\chi$SF QCD, related to the restoration of the theory's symmetries in the continuum limit. From the step scaling function of the pseudoscalar density we obtain the quark mass RG-running function from hadronic to perturbative energy scales. This is fully compatible with the earlier result obtained in a similar setup for Wilson quarks with Schr\"odinger Functional boundary conditions arXiv:1802.05243 and provides a strong universality test for the two lattice setups.

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Isabel Campos Plasencia, Mattia Dalla Brida, Giulia Maria de Divitiis, Andrew Lytle, Mauro Papinutto, Ludovica Pirelli, Anastassios Vladikas. 2021-12-20. Nonperturbative running of the quark mass for $N_f=3$ QCD from the chirally rotated Schr\"odinger Functional. https://arxiv.org/abs/2112.10606

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