An overview of neV probes of PeV scale physics – and of what's in between

Abstract

Abstract. Low-energy experiments which would identify departures from the Standard Model (SM) rely either on the unexpected observation of symmetry breaking, such as of CP or B, or on an observed significant deviation from a precise SM prediction. We discuss examples of each search strategy, and show that low-energy experiments can open windows on physics far beyond accessible collider energies. We consider how the use of a frequentist analysis framework can redress the impact of theoretical uncertainties in such searchesand how lattice QCD can help control them. ContextDirect searches for new physics at the LHC has yielded the discovery of the Higgs boson [1, 2], but no unanticipated, new particles -as yet. On the other hand, observational cosmology, analyzed in the framework of general relativity, tells us that only 4% of the energy density of the universe is in the matter we know [3], so that the SM of particle physics, successful though it is, is probably incomplete. The lack of evidence thus far for new physics and interactions through collider studies at the highest energies motivates broader thinking in the search for new physics. For example, the missing matter could be weakly coupled, making it more challenging if not impossible to identify in a collider environment. Low-energy, precision searches for new physics can also probe this alternative possibility and thus play a key role in the search for new physics. In this contribution we offer a terse overview of the diverse program these experiments comprise.Generally, there are two distinct search strategies. That is, one can either make null tests of the breaking of SM symmetries, or refine the measurement of quantities which can be computed, or assessed, precisely with the SM. In the former case, one can test, e.g., B-L invariance by searching for nn oscillations or neutrinoless double-decay. Although CP is not a symmetry of the SM, there are nevertheless observables for which the SM prediction is so small that searches at current levels of sensitivity also constitute null tests. Searches for permanent electric dipole moments (EDMs) of the neutron or electron, e.g., or for CP violation in the charm sector, be it through DD mixing or decay rate a