Speaker
Marc Illa
(U)
Description
In this talk I will report on a recent lattice QCD determination of few-body matrix elements made by the NPLQCD Collaboration. One of them is the fraction of the longitudinal momentum of ${}^3\text{He}$ that is carried by the isovector combination of $u$ and $d$ quarks. The ratio of this combination to that in the constituent nucleons is extracted in a calculation with quark masses corresponding to a pion mass of 800 MeV, and then extrapolated to the physical point, showing that it is consistent with, and significantly more precise than, determinations from global nuclear parton distribution function fits. The other quantity studied is the tritium axial charge, related to the Gamow-Teller matrix element, which is also computed with heavier-than-physical quark masses and then extrapolated and compared with the phenomenological value. The importance of this last study is that it demonstrates that QCD can explain the quenching of the triton axial charge.
Primary author
Marc Illa
(U)
