On the Quark Mass Dependence of Two Nucleon Observables

TL;DR

This paper explores how variations in quark masses affect two-nucleon observables using lattice QCD data and effective field theory, providing insights into fundamental physics and potential multiverse implications.

Contribution

It introduces a method to determine quark mass dependence of deuteron properties from lattice QCD and effective field theory, extending understanding of nuclear physics under varying quark masses.

Findings

Quark mass dependence of deuteron charge radius, magnetic moment, and polarizability calculated.

Lattice QCD data at unphysical quark masses used to inform nuclear effective field theory.

Results can constrain quark mass variation over cosmological timescales.

Abstract

We study the implications of lattice QCD determinations of the S-wave nucleon-nucleon scattering lengths at unphysical light quark masses. It is found that with the help of nuclear effective field theory (NEFT), not only the quark mass dependence of the effective range parameters, but also the leading quark mass dependence of all the low energy deuteron matrix elements can be obtained. The quark mass dependence of deuteron charge radius, magnetic moment, polarizability and the deuteron photodisintegration cross section are shown based on the NPLQCD lattice calculation of the scattering lengths at 354 MeV pion mass and the NEFT power counting scheme of Beane, Kaplan and Vuorinen. Further improvement can be obtained by performing the lattice calculation at smaller quark masses. Our result can be used to constrain the time variation of isoscalar combination of u and d quark mass m_q, to help the anthropic principle study to find the m_q range which allows the existence of life, and to provide a weak test of the multiverse conjecture.