0000000000773085
AUTHOR
Samoil M. Bilenky
Neutrino magnetic moment and the process neutrino e ---> neutrino e gamma
The contribution of a neutrino magnetic moment mu(nu) to the cross section of the process ve(-) --> ve(-)gamma has been calculated and compared with the Standard Electroweak one. The radiative process allows to reach low enough values of Q(2) without the need to operate at very small energies of recoil electrons. Regions in the phase space which are more favourable to set bounds on mu(v) are suggested.
Is it possible to determine the S-factor of the hep process from a laboratory experiment?
We discuss the problem of solar hep neutrinos originating from the reaction p + 3He -> 4He + e+ + nu and obtain a relation between the astrophysical S-factor of the hep process and the cross section of the process e- + 4He -> 3H + n + nu near threshold. The relation is based on the isotopic invariance of strong interactions. The measurement of the latter cross section would allow to obtain experimental information on S(hep), the value of which, at the moment, is known only from theoretical calculations.
Invisible width of the Z-boson and “secret” ν-ν interactions
Abstract The width of the decay Z→ν ν ν ν in the presence of a possible nonstandard four-fermion ν-ν interaction is calculated. From the invisible width of the Z-boson measured at LEP the upper bound on the strength F of such an effective interaction has been obtained: F≲4×102GF. This bound is about three orders of magnitude lower than earlier existing particle physics bounds and it is comparable with an estimate that can be obtained from supernova neutrino data. The expression for the spectrum of leptons in the decays W→lν l ν ν is also presented.