Nuclear aspects of neutral current non-standard ν-nucleus reactions and the role of the exotic μ ? → e ? transitions experimental limits

摘要

The nuclear aspects of flavour changing neutral current (FCNC) processes, predicted by various new-physics models to occur in the presence of nuclei, are examined by computing the relevant nuclear matrix elements within the context of the quasi-particle RPA using realistic strong two-body forces. One of our aims is to explore the role of the non-standard interactions (NSI) in the leptonic sector and specifically: (i) in lepton flavour violating (LFV) processes involving the neutral particlesν?andν??,?=e,μ,τand (ii) in charged lepton flavour violating (cLFV) processes involving the charged leptons??or?+. As concrete nuclear systems we have chosen the stopping targets ofμ?→e?conversion experiments, i.e. the48Ti nucleus of the PRIME/PRISM experiment at J-PARC and the27Al of the COMET at J-PARC as well as of the Mu2e at Fermilab. These experiments have been designed to reduce the single event sensitivity down to 10?16–10?18in searching for charged lepton mixing events. Our goal is, by taking advantage of our detailed nuclear structure calculations and using the present limits or the sensitivity of the aforementioned exoticμ?→e?experiments, to put stringent constraints on the parameters of NSI Lagrangians.