N. V. Mikheev

Neutrino energy and momentum loss through the process ν → νe−e+ in a strong magnetic field☆

Abstract The process of electron-positron pair production by neutrino propagating in a strong magnetic field is investigated in the framework of the Standard Model. The process probability and the mean values of the neutrino energy and momentum loss are calculated. Possible astrophysical manifestations of the process considered are briefly analysed.

Vector leptoquarks could be rather light

Abstract Some low-energy manifestations of a minimal extension of the Standard Model based on the quark-lepton SU(4)v × SU(2)L × GR symmetry of the Pati-Salam type are analysed. Given this symmetry a new type of mixing in the quark-lepton interactions is shown to be required. An additional arbitrariness of the mixing parameters could allow to decrease noticeably the lower bound on the leptoquark mass MX originated from the π and K decays and the μe conversion. The only mixing independent bound emerging from the cosmological limit on the π 0 → v v decay width is MX > 18 TeV.

Radiative decay of the massive neutrino in external electromagnetic fields

The radiative decay of the massive neutrino {nu}{sub {ital i}}{r_arrow}{nu}{sub {ital j}}{gamma} is investigated in the framework of the standard model in external electromagnetic fields of various configurations: constant crossed field, constant uniform magnetic field, plane monochromatic wave{close_quote}s field. The effect of significant enhancement of the neutrino decay probability by the external field (electromagnetic catalysis) is discussed. An especially strong enhancement occurs in the case of the ultrarelativistic neutrino decay, since in this case the decay probability does not contain suppression caused by the smallness of the decaying neutrino mass. The ultrarelativistic neutrino decay catalysis is significant even in a relatively weak external field ({ital F}/{ital F}{sub {ital e}}{lt}1, where {ital F}{sub {ital e}} is the critical Schwinger value). The expression for the photon splitting probability into a neutrino pair {gamma}{r_arrow}{nu}{sub {ital i}}{bar {nu}}{sub {ital j}} in the wave field is given. The estimations of a number of {gamma} quanta produced in a volume filled with an electromagnetic field and the neutrino lifetime in a strong magnetic field are presented. {copyright} {ital 1996 The American Physical Society.}

The magnetic catalysis of the radiative decay of a massive neutrino in the standard model with lepton mixing

Abstract The radiative decay of the massive neutrino in a magnetic field is analysed in detail in the framework of the standard model with lepton mixing. The phenomenon of a magnetic catalysis of the decay is discovered. The magnetic catalysis is significant in a strong magnetic field ( B⪢B e =m e 2 e≅4.41 × 10 13 G ) ;the effect is more pronounced in the case of the decay of an ultrarelativistic neutrino ( E v ⪢ m v ), even in a relatively weak electromagnetic field ( ϵB⪡m e 2 e ) .

Photon splitting above the pair creation threshold in a strong magnetic field

Abstract The process of photon splitting γ → γγ in a strong magnetic field is investigated both below and above the pair creation threshold. Contrary to the statement by Baier et al., the “allowed” channel γ ‖ → γ ⊥ γ ⊥ is shown not to be a comprehensive description of splitting in the strong field because the “forbidden” channel γ ‖ → γ ‖ γ ⊥ is also essential. The partial amplitudes and the splitting probabilities are calculated taking account of the photon dispersion and large radiative corrections near the resonance.

Resonance neutrino bremsstrahlung ν → νγ in a strong magnetic field

Abstract High energy neutrino bremsstrahlung ν → ν + γ in a strong magnetic field (B ⪢ Bs) is studied in the framework of the Standard Model (SM). A resonance probability and a four-vector of the neutrino energy and momentum loss are presented. A possible manifestation of the neutrino bremsstrahlung in astrophysical cataclysm of type of a supernova explosion or a merger of neutron stars, as an origin of cosmological γ-burst is briefly discussed.

Neutrino dispersion properties in an external magnetic field

The neutrino self-energy operator Σ(p) in a magnetic field is calculated for the case of high-energy neutrinos, this corresponding to the crossed field approximation. The probability of the neutrino decay ν → e−W+ is found by using the imaginary part of the operator Σ(p). A simple analytic result is obtained in the parameter region that is the most interesting from the physical point of view and which was not considered earlier. The contribution of an external magnetic field to the neutrino magnetic moment is calculated. The result obtained here for this contribution corrects formulas available previously.

THE THIRD TYPE OF FERMION MIXING IN THE LEPTON AND QUARK INTERACTIONS WITH LEPTOQUARKS

The low-energy manifestations of a minimal extension of the electroweak standard model based on the quark–lepton symmetry SU(4)V ⊗SU(2)L ⊗GR of the Pati–Salam-type are analyzed. Given this symmetry the third type of mixing in the interactions of the SU(4)V leptoquarks with quarks and leptons is shown to be required. An additional arbitrariness of the mixing parameters could allow, in principle, to decrease noticeably the lower bound on the vector leptoquark mass originated from the low-energy rare processes, strongly suppressed in the standard model.

High energy neutrino absorption by W production in a strong magnetic field

An influence of a strong external magnetic field on the neutrino self-energy operator is investigated. The width of the neutrino decay into the electron and W boson, and the mean free path of an ultra-high energy neutrino in a strong magnetic field are calculated. A kind of energy cutoff for neutrinos propagating in a strong field is defined.

Axion in an external electromagnetic field

We investigate the effective interaction of a pseudoscalar particle with two photons in an external electromagnetic field in the general case of all external particles being off the mass shell. This interaction is used to study the radiative decay