Quark-Mass Dependence of Light-Nuclei Masses from Lattice QCD and Trace-Anomaly Contributions to Nuclear Bindings

TL;DR

This study uses lattice QCD to analyze how light-nuclei masses depend on quark masses, revealing the dominant role of gluonic contributions in nuclear binding energies.

Contribution

First-principles lattice QCD calculations of light-nuclei masses across various quark masses, providing insights into quark-mass dependence and gluonic contributions to nuclear binding.

Findings

At physical quark masses, deuteron appears bound, dineutron unbound.

Binding energies' quark-mass dependence constrains nuclear interactions.

Gluonic contributions dominate the nuclear binding energy.

Abstract

We present lattice QCD calculations of the masses of the deuteron, dineutron, Helium-3 and Helium-4 with physical sea quarks and valence quark masses corresponding to pion masses between 140 and 700 MeV. At the physical point, the lowest finite-volume two-nucleon energy levels exhibit the qualitative pattern of a bound deuteron and an unbound dineutron within uncertainties, while at heavier quark masses they indicate the presence of deeply bound states. Compared with expectations from low-energy effective field theories, the observed mass dependence of the binding energies provides first-principles constraints on the quark-mass dependence of two- and three-nucleon interactions. From the quark-mass variation of the nuclear energies, we determine nuclear sigma terms and quantify the response of light-nuclear masses to changes in the light-quark mass. Using the QCD trace anomaly relation, we decompose the nuclear binding energy into quark-mass and gluonic contributions around the deuteron mass scale of $\mu=2$ GeV. We find that the quark-mass contribution to the binding energy is small and approximately additive in nucleon number within current precision, whereas the gluonic component provides the dominant contribution and show milder increases with mass number.