Lepton universality and lepton flavor conservation tests with dineutrino modes

Abstract

$SU(2{)}_L$-invariance links charged dilepton and dineutrino couplings. Phenomenological implications are worked out for flavor changing neutral currents involving strange, charm, beauty and top quark transitions in a model-independent way. We put forward novel tests of lepton universality and lepton flavor conservation in $|\Delta c|=|\Delta u|=1$ and $|\Delta b|=|\Delta q|=1$, $q=d,s$, transitions suitable for the experiments Belle II and BES III. Single top production plus dileptons uniquely probes semileptonic four-fermion $|\Delta t|=|\Delta q^{\prime }|=1$, $q^{\prime }=u,c$, couplings and further study at the LHC is encouraged. Tests with single top production associated with dileptons and missing energy are suitable for study at future $e^{+}{e}^{-}$ or muon colliders.

Comments: 10 pages, 4 figures, 7 tables. v2: Discussion of concrete applications of new method significantly expanded; contains analyses of FCNC strange, charm, beauty and top sectors. v3: References and minor clarifications added, conclusions unchanged. Matches published version