arXiv subjects

V. Skalozub

Publications and source records attributed to V. Skalozub.

32 records · Page 2Linked to original sources

arXiv2011

Lower bound on the magnetic field strength in the hot universe

It is assumed that long range coherent magnetic fields in the universe were spontaneously generated at high temperature due to vacuum polarization of non-Abelian gauge fields, and resulted in the present intergalaxy magnetic field. The zero value of the screening mass for fields of this type was discovered recently. Here, a procedure to estimate the field strengths at different temperatures is developed and the lower bound on the magnetic field strength $B \sim 10^{14} G$, at the electroweak phase transition temperature, is derived. As a particular case, the standard model is considered. Some model dependent peculiarities of the phenomena under investigation are briefly discussed.

hep-ph↗

arXiv2011

On the type of the temperature phase transition in phi-4 model

The temperature induced phase transition is investigated in the one-component scalar field ϕ^4 model on a lattice by using Monte Carlo simulations. Using the GPGPU technology a huge amount of data is collected that gives a possibility to determine the Linde-Weinberg low bound on the coupling constant λ_0 and investigate the type of the phase transition for a wide interval of coupling values. It is found that for the values of λclose to this bound a weak-first-order phase transition happens. It converts into a second order phase transition with the increase of λ. A comparison with analytic calculations in continuum field theory and lattice simulations obtained by other authors is given.

hep-lat↗

arXiv2008

Polarization tensor of charged gluons in color magnetic background field at finite temperature

We calculate the polarization tensor of charged gluons in a Abelian homogeneous magnetic background field at finite temperature in one loop order Lorentz background field gauge in full generality. Thereby we first determine the ten independent tensor structures. For the calculation of the corresponding form factors we use the Schwinger representation and represent form factors as double parametric integrals and a sum resulting from the Matsubara formalism used. The integrands are given explicitly in terms of hyperbolic trigonometric functions. Like in the case of neutral gluons, the polarization tensor is not transversal. Out of the tensor structures, seven are transversal and three are not. The nontransversal part follows explicitly from our calculations.

hep-th↗

arXiv2007

Spontaneous creation of chromomagnetic field and A_0-condensate at high temperature on a lattice

In a lattice formulation of SU(2)-gluodynamics, the spontaneous generation of chromomagnetic fields at high temperature is investigated. A procedure to determine this phenomenon is developed. By means of the $χ^2$-analysis of the data set accumulating $5-10\times 10^6$ Monte Carlo configurations, the spontaneous creation of the Abelian color magnetic field is indicated. The common generation of the magnetic field and $A_0$-condensate is also studied. It is discovered that the field configuration consisting of the magnetized vacuum and the $A_0$-condensate is stable.

hep-lat↗

arXiv2006

Neutral gluon polarization tensor in color magnetic background at finite temperature

In the framework of SU(2) gluodynamics, we derive the tensor structure of the neutral gluon polarization tensor in an Abelian homogeneous magnetic field at finite temperature and calculate it in one-loop approximation in the Lorentz background field gauge. The imaginary time formalism and the Schwinger operator method are used. The latter is extended to the finite temperature case. The polarization tensor turns out to be non transversal. It can be written as a sum of ten tensor structures with corresponding form factors. Seven tensor structures are transversal, three are not. We represent the form factors in terms of double parametric integrals and the temperature sum which can be computed numerically. As applications we calculate the Debye mass and the magnetic mass of neutral gluons in the background field at high temperature. A comparison with the results of other authors is done.

hep-th↗

arXiv2006

Gluon polarization tensor in color magnetic background

In SU(2) gluodynamics we calculate the gluon polarization tensor in an Abelian homogeneous magnetic field in one-loop order in the Lorentz background field gauge. It turned out to be non transversal and consisting of ten tensor structures and corresponding form factors - four in color neutral and six in color charged sector. Seven tensor structures are transversal, three are not. The non transversal parts are obtained by explicit calculation. We represent the form factors in terms of double parametric integrals which can be computed numerically. Some examples are provided and possible applications are discussed.

hep-th↗

arXiv2005

Non-transversality of the gluon polarization tensor in a chromomagnetic background

We investigate the question about the transversality of the gluon polarization tensor in a homogeneous chromomagnetic background field. We re-derive the non transversality known from a pure one loop calculation using the Slavnov-Taylor identities. In addition we generalize the procedure to arbitrary gauge fixing parameter $ξ$ and calculate the $ξ$-dependent part of the polarization tensor.

hep-th↗

arXiv2002

First order phase transition and corrections to its parameters in the O(N) - model

The temperature phase transition in the $N$-component scalar field theory with spontaneous symmetry breaking is investigated using the method combining the second Legendre transform and with the consideration of gap equations in the extrema of the free energy. After resummation of all super daisy graphs an effective expansion parameter, $(1/2N)^{1/3}$, appears near $T_c$ for large $N$. The perturbation theory in this parameter accounting consistently for the graphs beyond the super daisies is developed. A certain class of such diagrams dominant in 1/N is calculated perturbatively. Corrections to the characteristics of the phase transition due to these contributions are obtained and turn out to be next-to-leading order as compared to the values derived on the super daisy level and do not alter the type of the phase transition which is weakly first-order. In the limit $N$ goes to infinity the phase transition becomes second order. A comparison with other approaches is done.

hep-th↗

arXiv2001

Temperature phase transition and an effective expansion parameter in the O(N)-model

The temperature phase transition in the N-component scalar field theory with spontaneous symmetry breaking is investigated in the perturbative approach. The second Legendre transform is used together with the consideration of the gap equations in the extrema of the free energy. Resummations are performed on the super daisy level and beyond. The phase transition turns out to be weakly of first order. The diagrams beyond the super daisy ones which are calculated correspond to next-to-next-to-leading order in 1/N. It is shown that these diagrams do not alter the phase transition qualitatively. In the limit N goes to infinity the phase transition becomes second order. A comparison with other approaches is done.

hep-th↗

arXiv2000

Phase transition in scalar $ϕ^4$-theory beyond the super daisy resummations

The temperature phase transition in scalar $ϕ^4(x)$ field theory with spontaneous symmetry breaking is investigated in a partly resummed perturbative approach. The second Legendre transform is used and the resulting gap equation is considered in the extrema of the free energy functional. It is found that the phase transition is of first order in the super daisy as well as in a certain beyond super daisy resummations. No unwanted imaginary parts in the free energy are found but a loss of the smallness of the effective expansion parameter near the phase transition temperature is found in both cases. This means an insufficiency of the resummations or a deficit of the perturbative approach.

hep-th↗

arXiv1999

Electroweak Phase Transition in Strong Magnetic Fields in the Standard Model of Elementary Particles

The electroweak phase transition in the magnetic and hypermagnetic fields is studied in the Standard Model on the base of investigation of symmetry behaviour within the consistent effective potential of the scalar and magnetic fields at finite temperature. It includes the one-loop and daisy diagram contributions. All discovered fundamental fermions and bosons are taken into consideration with their actual masses. The Higgs boson mass is chosen to be in the energy interval 75 GeV $\le m_H \le$ 115 GeV. The effective potential calculated is real at sufficiently high temperatures due to mutual cancellation of the imaginary terms entering the one-loop and the daisy diagram parts. Symmetry behaviour shows that neither the magnetic nor the hypermagnetic field does not produce the sufficiently strong first order phase transition. For the field strengths $H, H_Y$ $\ge 10^{23}$ G the electroweak phase transition is of second order at all. Therefore, baryogenesis does not survive in the Standard Model in smooth magnetic fields. The problems on generation of the fields at high temperature and their stabilization are also discussed in a consistent way. In particular, it is determined that the nonabelian component of the magnetic field $ (gH)^{1/2} \sim g^{4/3}T$ has to be produced spontaneously. To investigate the stability problem the $W$-boson mass operator in the magnetic field at high temperature is calculated in one-loop approximation. The comparison with results obtained in other approaches is done.

hep-th↗

arXiv1999

On Symmetry Restoration at Finite Temperature (Scalar Case)

We investigate the effective potential for a scalar $Φ^{4}$ theory with spontaneous symmetry breaking at finite temperature. All 'daisy' and 'super daisy' diagrams are summed up and the properties of the corresponding gap eqation are investigated. It is shown exactly that the phase transition is first order.

hep-th↗

arXiv1999

Ring diagrams and electroweak phase transition in a magnetic field

Electroweak phase transition in a magnetic field is investigated within the one-loop and ring diagram contributions to the effective potential in the minimal Standard Model. All fundamental fermions and bosons are included with their actual values of masses and the Higgs boson mass is considered in the range $75 GeV \leq m_H \leq 115 GeV$. The effective potential is real at sufficiently high temperature. The important role of fermions and $W$-bosons in symmetry behaviour is observed. It is found that the phase transition for the field strengths $10^{23} - 10^{24}$G is of first order but the baryogenesis condition is not satisfied. The comparison with the hypermagnetic field case is done.

hep-ph↗

arXiv1998

Electroweak phase transition in a strong magnetic field

Phase transitions induced by high temperatures and strong magnetic fields are investigated in the Standard model. The consistent effective potential including the one-loop and ring diagram contributions is calculated and investigated for the wide range of the fields, temperatures and Higgs boson mass $m_H$. All other particles - fermions and bosons - are taken into account with actual values of their masses. This effective potential is real at sufficiently high temperatures . It is shown that symmetry restoration is a first type phase transition for $m_H < 70 $ Gev . For heavier Higgs particles and the field strengths $H > 0.1 \cdot 10^{24} G $ the local electroweak minimum could not be realized at all. Hence, the upper limit on the Higgs mass as well as the limit on the field strengths in the phase transition epoch follow.

hep-ph↗