NT/RIKEN Seminar

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.