Персона: Никулин, Валерий Владимирович
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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
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Никулин
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Валерий Владимирович
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- ПубликацияТолько метаданныеFormation of Primordial Black Hole Clusters from Phase Transitions in the Early Universe(2019) Nikulin, V. V.; Rubin, S. G.; Kirillov, A. A.; Khromykh, L. A.; Никулин, Валерий Владимирович; Рубин, Сергей Георгиевич; Кириллов, Александр Александрович© 2019, Allerton Press, Inc. A new model of the formation of primordial black holes (PBHs) is considered. The PBH generation mechanism is based on the collapse of massive walls formed in a scalar field during second-order phase transitions caused by quantum fluctuations during inflation. An essential feature of the mechanism is the formation of primordial black holes in the form of clusters. An analytical spectrum of PBH masses is obtained. We also demonstrate the possibility of forming the clusters with a total mass of ∼ 10 5 –10 8 M ☉ , ∼ 1 pc in size, and ∼ 10 11 in number, which corresponds to the observational data on the number of galaxies in the visible region of the Universe. The prospect for the use of the proposed approach as a new scenario of the formation of galactic nuclei in the early Universe is shown.
- ПубликацияТолько метаданныеCosmological baryon/lepton asymmetry in terms of Kaluza-Klein extra dimensions(2021) Nikulin, V. V.; Rubin, S. G.; Никулин, Валерий Владимирович; Рубин, Сергей Георгиевич© 2021 World Scientific Publishing Company.In this paper, we discuss the mechanism for generating the lepton/baryon number and its subsequent conservation based on extra-dimensional evolution. The internal angular momentum of extra space is related to the lepton/baryon charge. Extra space metric is assumed to be initially asymmetric. Symmetries appear during inflation due to an increase in entropy. Using the multidimensional field toy model, we show that internal angular momentum can accumulate in fermions, which could explain the lepton/baryon asymmetry of the universe.
- ПубликацияТолько метаданныеCompact extra dimensions as the source of primordial black holes(2022) Nikulin, V. V.; Krasnov, M. A.; Rubin, S. G.; Никулин, Валерий Владимирович; Краснов, Максим Александрович; Рубин, Сергей ГеоргиевичThis article discusses a model of primordial black hole (PBH) formation at the reheating stage. These small/massive black holes appear due to the specific properties of the compact extra dimensions. The latter gives rise to the low energy model, containing an effective scalar field potential capable of domain wall production. Formed during inflation, these walls are quite dense, meaning they collapse soon after inflation ends. Discussion of the model is framed by the scope of multidimensional f ( R )-gravity. We study the possibility of the pure gravitational formation of primordial black holes (PBHs). Interpreting the scalar curvature of compact extra space R n as an effective scalar field in an Einstein framework and consider effective scalar-field theory that might potentially be capable of producing domain walls with a certain choice of parameters. Hence, we demonstrate that f ( R )-gravity contains a mechanism for PBH formation. The study assumed that cosmological inflation is an external process, which satisfied all the cosmological constraints on our mechanism.
- ПубликацияТолько метаданныеInflationary limits on the size of compact extra space(2019) Nikulin, V. V.; Rubin, S. G.; Никулин, Валерий Владимирович; Рубин, Сергей Георгиевич© 2019 World Scientific Publishing Company. We study restrictions imposed on the parameters of the Kaluza-Klein extra space supplied by the standard inflationary models. It is shown that the size of the extra space cannot be larger than ∼ 10-27cm and the D-dimensional Planck mass should be larger than ∼ 1013GeV. The validity of these estimates is discussed. We also study creation of stable excitations of scalar field as the result of the extra metric evolution.
- ПубликацияОткрытый доступFormation of Conserved Charge at the de Sitter Space(2020) Nikulin, V. V.; Petriakova, P. M.; Rubin, S. G.; Никулин, Валерий Владимирович; Рубин, Сергей ГеоргиевичThe article considers a new mechanism of charge accumulation in the early Universe in theories with compact extra dimensions. The relaxation processes in the extra space metric that take place during its formation lead to the establishment of symmetrical extra space configuration. As a result, the initial accumulation of the number associated with the symmetry occurs. We demonstrate this mechanism using a simple example of a two-dimensional apple-like extra space metric with U(1)-symmetry. The conceptual idea of the mechanism can be used to develop a model for the production of the baryon or lepton number in the early Universe.
- ПубликацияОткрытый доступClusters of Primordial Black Holes(2019) Eroshenko, Y. N.; Khlopov, M. Y.; Belotsky, K. M.; Dokuchaev, V. I.; Esipova, E. A.; Khromykh, L. A.; Kirillov, A. A.; Nikulin, V. V.; Rubin, S. G.; Svadkovsky, I. V.; Белоцкий, Константин Михайлович; Есипова, Екатерина Александровна; Кириллов, Александр Александрович; Никулин, Валерий Владимирович; Рубин, Сергей Георгиевич; Свадковский, Игорь Витальевич© 2019, The Author(s). The Primordial Black Holes (PBHs) are a well-established probe for new physics in the very early Universe. We discuss here the possibility of PBH agglomeration into clusters that may have several prominent observable features. The clusters can form due to closed domain walls appearance in the natural and hybrid inflation models whose subsequent evolution leads to PBH formation. The dynamical evolution of such clusters discussed here is of crucial importance. Such a model inherits all the advantages of uniformly distributed PBHs, like possible explanation of supermassive black holes existence (origin of the early quasars), the binary black hole mergers registered by LIGO/Virgo through gravitational waves, which could provide ways to test the model in future, the contribution to reionization of the Universe. If PBHs form clusters, they could alleviate or completely avoid existing constraints on the abundance of uniformly distributed to PBH, thus allowing PBH to be a viable dark matter candidate. Most of the existing constraints on uniform PBH density should be re-considered to the case of PBH clustering. Furthermore, unidentified cosmic gamma-ray point-like sources could be (partially) accounted. We conclude that models leading to PBH clustering are favored compared to models predicting the uniform distribution of PBHs.