arXiv subjects

Daniela Kirilova

Publications and source records attributed to Daniela Kirilova.

8 recordsLinked to original sources

arXiv2020

Scalar Field Condensate Baryogenesis Model in Different Inflationary Scenarios

We calculate the baryon asymmetry value generated in the Scalar Field Condensate (SCF) baryogenesis model obtained in several inflationary scenarios and different reheating models. We provide analysis of the baryon asymmetry value obtained for more than 70 sets of parameters of the SCF model and the following inflationary scenarios, namely: new inflation, chaotic inflation, Starobinsky inflation, MSSM inflation, quintessential inflation. We considered both cases of efficient thermalization after inflation and also delayed thermalization. We have found that SFC baryogenesis model produces baryon asymmetry by orders of magnitude bigger than the observed one for the following inflationary models: new inflation, new inflation model by Shafi and Vilenkin, MSSM inflation, chaotic inflation with high reheating temperature and the simplest Shafi-Vilenkin chaotic inflationary model. For these models strong diluting mechanisms are needed to reduce the resultant baryon excess at low energies to its observational value today. We have found that a successful generation of the observed baryon asymmetry is possible by SCF baryogenesis model in Modified Starobinsky inflation, chaotic inflation with low reheating temperature, chaotic inflation in SUGRA and Quintessential inflation.

hep-ph↗

arXiv2015

Parameterizing the SFC Baryogenesis Model

We have numerically explored the Scalar Field Condensate baryogenesis model for numerous sets of model's parameters, within their natural range of values. We have investigated the evolution of the baryon charge carrying field, the evolution of the baryon charge contained in the scalar field condensate and the final value of the generated baryon charge on the model's parameters: the gauge coupling constant $α$, the Hubble constant at the inflationary stage $H_I$, the mass $m$, the self-coupling constants $λ_i$.

hep-ph↗

arXiv2014

Neutrinos from the Early Universe and Physics Beyond Standard Models

Neutrino oscillations present the only robust example of experimentally detected physics beyond the standard model. This review discusses the established and several hypothetical beyond standard models neutrino characteristics and their cosmological effects and constraints. Particularly, the contemporary cosmological constraints on the number of neutrino families, neutrino mass differences and mixing, lepton asymmetry in the neutrino sector, neutrino masses, light sterile neutrino are briefly reviewed.

astro-ph.CO↗

arXiv2013

Lepton Asymmetry and Neutrino Oscillations Interplay

We discuss the interplay between lepton asymmetry L and neutrino oscillations in the early Universe. Neutrino oscillations may suppress or enhance previously existing L. On the other hand L is capable to suppress or enhance neutrino oscillations. The mechanism of L enhancement in MSW resonant neutrino oscillations in the early Universe is numerically analyzed. L cosmological effects through neutrino oscillations are discussed. We discuss how L may change the cosmological BBN constraints on neutrino and show that BBN model with electron-sterile neutrino oscillations is extremely sensitive to L - it allows to obtain the most stringent constraints on L value. We discuss also the cosmological role of active-sterile neutrino mixing and L in connection with the indications about additional relativistic density in the early Universe, pointed out by BBN, CMB and LSS data and the analysis of global neutrino data.

astro-ph.CO↗

arXiv2004

Neutrino Spectrum Distortion Due to Oscillations and its BBN Effect

We study the distortion of electron neutrino energy spectrum due to oscillations with the sterile neutrino nu_e <-> nu_s, for different initial populations of the sterile state delta N_s at the onset of oscillations. The influence of this spectrum distortion on Big Bang Nucleosynthesis is analyzed. Only the case of an initially empty sterile state was studied in previous publications. The primordial abundance of He-4 is calculated for all possible delta N_s: 0<= delta N_s<= 1 in the model of oscillations, effective after electron neutrino decoupling, for which the spectrum distortion effects on the neutron--proton transitions are the strongest. It is found that the spectrum distortion effect may be the dominant one not only in the case of small delta N_s, but also in the case of big initial population of nu_s. For example, in the resonant case it may play a considerable role even for very big delta N_s ~ 0.8.

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↗