arXiv subjects

N. V. Mikheev

Publications and source records attributed to N. V. Mikheev.

80 records · Page 5Linked to original sources

arXiv1994

One More Source of Information on the Lepton Mixing Angles

In the framework of the Standard Model with lepton mixing the radiative decay $ν_i \rightarrow ν_j γ$ of a neutrino of high ($E_ν\sim 100 \, GeV$) and super-high ($E_ν\ge 1 \, TeV$) energy is investigated in the Coulomb field of a nucleus. Estimates of the decay probability and ``decay cross-section'' for neutrinos of these energies in the electric field of nucleus permit one to discuss the general possibility of carrying out the neutrino experiment, subject to the condition of availability in the future of a beam of neutrinos of that high energies. Such an experiment could give unique information on mixing angles in the lepton sector of the Standard Model which would be independent of the specific neutrino masses if only the threshold factor ($1 - m_j^4 / m_i^4$) was not close to zero.

hep-ph↗

arXiv1994

Rare Electroweak Processes $K^0_L \to μ^+ μ^-$ and $K^0_L \to γγ$ and Heavy Top Quark

A brief overview of the recent measurements of the branching ratio of the rare $K_L^0 \to μ^+ μ^-$ decay in the context of their agreement with the Standard Model (SM) is given. It is shown that KEK result well correlates with the SM and B-physics, whereas the BNL results are in conflict with the SM with the heavy top quark.

hep-ph↗

arXiv1994

The Electromagnetic Catalysis of the Neutrino Radiative Decay

The radiative decay of the massive neutrino $ν_i \rightarrow ν_j γ( m_i > m_j )$ in the external electromagnetic field is analyzed in detail in the framework of the standard model with lepton mixing. It is shown, that a sort of a catalysis of the neutrino radiative decay takes place. The effect of catalysis is significant in the strong electromagnetic fields ($F \gg B_e = m^2_e / e \simeq 4.41 \cdot 10^{13}$ G) ; it is more pronounced in the case of the decay of the ultrarelativistic neutrino $(E_ν \gg m_ν)$, even in a relatively weak electromagnetic field ($F \ll m^2_e/e$).

hep-ph↗

arXiv1994

Could Vector Leptoquarks be Rather Light?

A possible Standard Model extension of the Pati-Salam type with a lepton number as the fourth color is reexamined. A new type of mixing in the interaction of the $SU(4)_V$--leptoquark with quarks and leptons is shown to be required. An additional arbitrariness of the mixing parameters could allow to decrease noticeably the lower bound on the leptoquark mass $M_X$ originated from the $π$ and $K$ decays and the $μe$ conversion. The only mixing independent bound emerging from the cosmological limit on the $π^0 \rightarrow ν\barν$ decay width is $M_X > 18~TeV$.

hep-ph↗

arXiv1994

Vector Leptoquarks Could Be Rather Light?

Some low-energy manifestations of a minimal extension of the Standard Model based on the quark-lepton $SU(4)_V \otimes SU(2)_L \otimes G_R$ 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 $M_X$ originated from the $π$ and $K$ decays and the $μe$ conversion. The only mixing independent bound emerging from the cosmological limit on the $π^0 \rightarrow ν\barν$ decay width is $M_X > 18~TeV$.

hep-ph↗

arXiv1994

The radiative decay of a high energy neutrino in the Coulomb field of a nucleus

In the framework of the Standard Model with lepton mixing the radiative decay $ν_i \rightarrow ν_j γ$ of a neutrino of high ($E_ν\sim 100 \, GeV$) and super-high ($E_ν\ge 1 \, TeV$) energy is investigated in the Coulomb field of a nucleus. Estimates of the decay probability and ``decay cross-section'' for neutrinos of these energies in the electric field of a nucleus permit one to discuss the general possibility of carrying out a neutrino experiment, subject to the condition of availability in the future of a beam of neutrinos of these high energies. Such an experiment could give unique information on mixing angles in the lepton sector of the Standard Model which would be independent of the specific neutrino masses if only the threshold factor ($1 - m_j^4 / m_i^4$) was not close to zero. (Published in Phys.Lett.B 323 (1994) 179).

hep-ph↗

arXiv1994

Electromagnetic catalysis of the radiative transitions of $ν_i \rightarrow ν_j γ$ type in the field of an intense monochromatic wave

The radiative decay of the massive neutrino $ν_i \rightarrow ν_j γ$ in a circularly polarized electromagnetic wave is investigated within the Standard theory with lepton mixing. The decay probability in the wave field does not contain a threshold factor $\sim ( 1 - m_i / m_j )$ as opposed to the decay probability in a vacuum or in a constant uniform external field. The phenomenon of the gigantic enhancement ( $\sim 10^{33}$ ) of the neutrino decay probability in external wave field is discovered. The probability of the photon splitting into the neutrino pair is obtained. (Published in Phys.Lett.B 321 (1994) 108).

hep-ph↗

arXiv1994

Double radiative decay $Z \rightarrow f\bar{f}γγ$ in the Standard Model

Z-boson decay $Z \rightarrow f\tilde{f}γγ$ in the Standard Model is analysed. The distribution function on the invariant masses of the photon and fermion pairs is calculated in the leading logarithmic approximation. It is shown that this distribution function has a specific shape of a ``crest''. (To be published in Mod.Phys.Lett.A)

hep-ph↗