Ruling Out the Massless Up-Quark Solution to the Strong CP Problem by Computing the Topological Mass Contribution with Lattice QCD
High Energy Physics - Lattice
2021-03-02 v3 High Energy Physics - Phenomenology
High Energy Physics - Theory
Abstract
The infamous strong CP problem in particle physics can in principle be solved by a massless up quark. In particular, it was hypothesized that topological effects could substantially contribute to the observed nonzero up-quark mass without reintroducing CP violation. Alternatively to previous work using fits to chiral perturbation theory, in this Letter, we bound the strength of the topological mass contribution with direct lattice QCD simulations, by computing the dependence of the pion mass on the dynamical strange-quark mass. We find that the size of the topological mass contribution is inconsistent with the massless up-quark solution to the strong CP problem.
Keywords
Cite
@article{arxiv.2002.07802,
title = {Ruling Out the Massless Up-Quark Solution to the Strong CP Problem by Computing the Topological Mass Contribution with Lattice QCD},
author = {Constantia Alexandrou and Jacob Finkenrath and Lena Funcke and Karl Jansen and Bartosz Kostrzewa and Ferenc Pittler and Carsten Urbach},
journal= {arXiv preprint arXiv:2002.07802},
year = {2021}
}
Comments
10 pages, 3 figures, updated references