Abstract
In this paper, we show how a presence of the exotic scalar, tensor weak interactions in addition to the standard vector-axial (V-A) one may help to distinguish the Dirac from Majorana neutrinos in the elastic scattering of (anti)neutrino beam off the unpolarized electrons in the limit of vanishing (anti)neutrino mass. We assume that the incoming (anti)neutrino beam comes from the polarized muon decay at rest and is the left-right chiral mixture with assigned direction of the transversal spin polarization with respect to the production plane. We display that the azimuthal asymmetry in the angular distribution of recoil electrons is generated by the interference terms between the standard and exotic couplings, which are proportional to the transversal (anti)neutrino spin polarization and independent of the neutrino mass. This asymmetry for the Majorana neutrinos is distinct from the one for the Dirac neutrinos through the absence of interference between the standard and tensor couplings. Additionally, the interference term between the standard and scalar coupling of the only left chiral neutrinos, absent in the Dirac case, appears. We also indicate the possibility of utilizing the azimuthal asymmetry measurements to search for the new CP-violating phases. Our analysis is model-independent and consistent with the current upper limits on the non-standard couplings.
Highlights
One of the fundamental problems in the neutrino physics is whether the neutrinos (ν)’s are the Dirac or Majorana fermions
There is an alternative way within the relativistic limit, when one admits the existence of exotic scalar (S), tensor (T ), pseudoscalar (P) and V + A weak interactions of the right chiral (RCh) ν’s in addition to the V − A interaction of the left chiral (LCh) ones in the above processes
We have shown that there is the distinction between the Dirac and Majorana flavour ν’s in the relativistic limit, when the incoming ν beam is the superposition of LCh and RCh states, and has the fixed direction of transversal component of theneutrino spin polarization with respect to the production plane
Summary
One of the fundamental problems in the neutrino physics is whether the neutrinos (ν)’s are the Dirac or Majorana fermions. The differential cross section for the scattering of Dirac νe’s off the unpolarized electrons, in the relativistic limit, is of the form (the formula in [77] does not contain the contributions from the cSL,T couplings because they do not interfere with the cVL,A). The amplitude for the elastic scattering of the Majorana electron neutrinos (νe’s) on the unpolarized electrons at low energies has the form (a similar amplitude is for νμ’s with the appropriate change of couplings cV , cA, cV , cA, cSL,,TR → gV , gA, gV , gA, gSL,,TR). The other assumptions concerning the production of νe beam and the detection of νe’s by the interaction with the unpolarized electron target are the same as in the Dirac scenario
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
