Lattice QCD Input for Fundamental Symmetry Tests

Lattice QCD Input for Fundamental Symmetry Tests
Michael Wagman, MIT
Date and time: Tue, Oct 23, 2018 - 2:30pm
Location: LGRT 419B
Category: ACFI Seminar
Abstract:

Experimental detection of fundamental symmetry violation
would provide a clear signal for new physics, but theoretical
predictions that can be compared with data are needed in order to
interpret experimental results as measurements or constraints of
beyond the Standard Model physics parameters. For low-energy
experiments involving protons, neutrons, and nuclei, reliable
theoretical predictions must include the strong interactions of QCD
that confine quarks and gluons. I will discuss experimental searches
for neutron-antineutron oscillations that test beyond the Standard
Model theories of matter-antimatter asymmetry with low-scale
baryon-number violation. Lattice QCD can be used to calculate the
neutron-antineutron transition rate using a complete basis of
six-quark operators describing neutron-antineutron oscillations in
effective field theory, and I will present the first lattice QCD
results for neutron-antineutron oscillations using physical quark mass
simulations and fully quantified uncertainties. Other experiments
searching for neutrinoless double-beta decay and dark matter direct
detection use large nuclear targets that are more difficult to
simulate in lattice QCD because of an exponentially difficult
sign(al-to-noise) problem. I will briefly describe the
state-of-the-art for lattice QCD calculations of axial, scalar, and
tensor matrix elements relevant to new physics searches with nuclei
and outline my ongoing efforts to improve signal-to-noise problems
using phase unwrapping.