arXiv subjects

V. V. Nikulin

Publications and source records attributed to V. V. Nikulin.

5 recordsLinked to original sources

arXiv2025

Soliton foam formation in the early Universe

The formation of composite solitons produced by scalar fields without thermal phase transitions in the early Universe is considered. We present numerical simulations of the formation and evolution of soliton structures at the post-inflationary stage. The realistic initial conditions are obtained through the simulation of multiple quantum fluctuations during the inflation epoch. The initial field distributions allow to form local soliton clusters in the early Universe without the need for the thermal production of a soliton network throughout the Universe. We find that in three-dimensional space, the nontrivial composite field structures are formed in the form of < >, consisting of closed domain walls, domain walls bounded by cosmic strings, and scalar field radiation. The possible cosmological implications of the soliton foam are discussed.

hep-th↗

arXiv2021

Cosmological Formation of (2+1)-Dimensional Soliton Structures in Models Possessing Potentials with Local Peaks

Production of domain walls and string-like solitons in the model with two real scalar fields and potential with at least one saddle point and a local maximum is considered. The model is regarded as 2-dimensional spatial slices of 3-dimensional entire structures. It is shown that, in the early Universe, both types of solitons may appear. In addition, the qualitative estimate of the domain walls and strings formation probabilities is presented. It is found that the probability of the formation of string-like solitons is suppressed compared to that of domain walls.

hep-th↗

arXiv2020

Formation of conserved charge at the de Sitter space

The 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.

gr-qc↗

arXiv2006

On a classical correspondence between K3 surfaces III

Let $X$ be a K3 surface, and $H$ its primitive polarization of the degree $H^2=8$. The moduli space of sheaves over $X$ with the isotropic Mukai vector $(2,H,2)$ is again a K3 surface, $Y$. In math.AG/0206158 we gave necessary and sufficient conditions in terms of Picard lattice of $X$ when $Y$ is isomorphic to $X$. The proof of sufficient condition in math.AG/0206158, when $Y$ is isomorphic to $X$, used Global Torelli Theorem for K3 surfaces, and it was not effective. Here we give an effective variant of these results: its sufficient part gives an explicit isomorphism between $Y$ and $X$. We hope that our similar results in math.AG/0304415, math.AG/0307355, math.AG/0309348 for arbitrary primitive isotropic Mukai vector on a K3 surface also can be made effective.

math.AG↗

arXiv1993

On Brauer Groups of Real Enriques Surfaces

Let Y be a real Enriques surface, _2Br(Y) the subgroup of elements of order 2 of Br(Y), and s, s_{or}, and s_{nor} the number of all connected, connected orientable, and connected non-orientable components of Y(R) respectively. Using universal covering K3-surface X of Y, we connect dim _2Br(Y) with the s, s_{or} and s_{nor}. As a geometric corollary of our considerations, we show that s \le 6 and s_{nor} \le 4.

alg-geom↗