Decay of polarized muon at rest as a source of polarized neutrino beam

In this paper, we indicate the theoretical possibility of using the decay of polarized muons at rest as a source of the transversely polarized electron antineutrino beam. Such a beam can be used to probe new effects beyond standard model. We mean here new tests concerning CP violation, Lorentz structure and chirality structure of the charged current weak interactions. The main goal is to show how the energy and angular distribution of the electron antineutrinos in the muon rest frame depends on the transverse components of the antineutrino beam polarization. We admit the participation of the complex exotic scalar and tensor couplings of the right-chirality electron antineutrinos in addition to the standard vector coupling of the left-chirality ones, while the muon neutrinos are always left-chirality. It means that the outgoing electron antineutrino beam is a mixture of the leftand right-chirality antineutrinos and has the fixed direction of the transverse spin polarization with respect to the production plane. Our analysis is model-independent and consistent with the current upper limits on the non-standard couplings. The results are presented in a limit of infinitesimally small mass for all particles produced in the decay.