arXiv subjects

Mihail Chizhov

Publications and source records attributed to Mihail Chizhov.

4 recordsLinked to original sources

arXiv2020

Mass prediction for the last discovered member of the axial-vector nonet with quantum numbers J$^{PC}=1^{+-}$

In this paper we have shown that the novel mass relation among the vector states, $ϕ(1020)$ and $ϕ(1680)$, with quantum numbers J$^{PC}=1^{--}$ and axial-vector strangeonium state $h_1(s\bar{s})$ with quantum numbers $1^{+-}$ is also valid for nonzero current quark mass. This relation predicts the mass of recently discovered $h_1(s\bar{s})$ state by the Collaboration BESIII within experimental accuracy.

hep-ph↗

arXiv2001

Big Bang Nucleosynthesis and Cosmological Constraints on Neutrino Oscillation Parameters

We present a review of cosmological nucleosynthesis (CN) with neutrino oscillations, discussing the different effects of oscillations on CN, namely: increase of the effective degrees of freedom during CN, spectrum distortion of the oscillating neutrinos, neutrino number density depletion, and growth of neutrino-antineutrino asymmetry due to active-sterile oscillations. We discuss the importance of these effects for the primordial yield of helium-4. Primordially produced He-4 value is obtained in a selfconsistent study of the nucleons and the oscillating neutrinos. The effects of spectrum distortion, depletion and neutrino-antineutrino asymmetry growth on helium-4 production are explicitly calculated. An update of the cosmological constraints on active-sterile neutrino oscillations parameters is presented, giving the values: delta m^2 sin^8 (2 theta) < 1.5 x 10^{-9} eV^2 for delta m^2 > 0, and |delta m^2| < 8.2 x 10^{-10} eV^2 at large mixing angles for delta m^2 < 0. According to these constraints, besides the active-sterile LMA solution, also the active-sterile LOW solution to the solar neutrino problem is almost totally excluded.

astro-ph↗

arXiv2001

Lepton asymmetry effect on neutrino oscillations and primordial He-4

We analyze the effects of lepton asymmetry on neutrino oscillations and on cosmological nucleosynthesis with active-sterile oscillating neutrinos. It is shown that small lepton asymmetries, L < 0.01, whose direct kinetic effect on nucleosynthesis is negligible, still effect nucleosynthesis considerably through their influence on oscillating neutrinos. Two different cases of lepton asymmetry are discussed: an initially present and a dynamically generated in oscillations. Dynamically generated in resonant oscillations asymmetry at small mixing angles suppresses oscillations, hence, the nucleosynthesis bounds on neutrino mass differences at small mixings are relaxed. Initially present asymmetry may suppress or enhance oscillations. The enhancement is a result of interchanging resonances between neutrino and antineutrino ensembles due to resonance waves passing through the neutrino and antineutrino spectrum. Updated nucleosynthesis bounds on neutrino oscillation parameters accounting for lepton asymmetry are presented.

astro-ph↗

arXiv1998

Neutrino degeneracy effect on neutrino oscillations and primordial helium yield

In this work we present the results of our numerical analysis of the effect of lepton asymmetries L on neutrino oscillations and consequently on helium production in a model of cosmological nucleosynthesis with active-sterile neutrino oscillations. We performed detail calculations of the neutron-proton ratio till its freezing and the subsequent synthesis of helium-4 for a wide range of values of the initial lepton asymmetry 10^{-4}-10^{-10} and for the complete set of mixing parameters of the oscillation model described in hep-ph/9707282: δm^2 \le 10^{-7} eV^2 and any \vartheta. We have found that there are significant modifications of neutrino number densities and energy distributions over a large range of values of the initial asymmetry. Hence, the previously derived (for the case of lepton asymmetry of the order of the baryon one) nucleosynthesis limits on the oscillation parameters are considerably altered. We have calculated the dependence of primordially produced helium-4 on the parameters of the model Y_p(L, δm^2, \vartheta). From the isohelium contours in the δm^2-\vartheta plane, we have obtained limits on the neutrino mixing parameters corresponding to nucleosynthesis with degenerate neutrinos. An intriguing new result of our analysis is that the lepton asymmetry is able to tighten the nucleosynthesis bounds on neutrino mixing parameters, besides its well known ability to relax them.

hep-ph↗