Nuclear physics, lattice QCD, and the search for physics beyond the Standard Model - Andre Walker-Loud (LBNL)

Abstract: Precision, low-energy experiments provide complimentary constraints on the search for new physics.  These often take the form of looking for violations of symmetries of the Standard Model, such as Lepton Number.  A discovery signal of lepton number violation, such as the observation of neutrinoless double beta decay, would offer definitive evidence of new physics. Other experiments look to test the Vector minus Axial structure of the Standard Model, through precision beta-decay experiments, looking for corrections to the spectral shape, and/or determining the CKM matrix elements and looking for unitarity violations.  Long baseline neutrino experiments aim to measure more precisely, or for the first time, parameters of the corresponding PMNS neutrino mixing matrix.  Common to many of these experiments is the use of nucleons or nuclei as laboratories.  As such, in order to interpret null results as constraints on new physics, and/or to tease out specific models that can describe hopeful new signals, and/or to control the Standard Model “background”, it is important to have a theoretical description of the various phenomena with as much rigorous theory uncertainty as possible.  To achieve this goal, a coordinated effort between lattice QCD, effective field theory and nuclear many-body methods is required in order to build a quantitative connection between our understanding of nuclear physics and the underlying quark and gluon interactions.  I will describe some recent progress and challenges towards this goal, with an emphasis on the lattice QCD and effective field theory aspects and interface.