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E. Nugaev

Publications and source records attributed to E. Nugaev.

5 recordsLinked to original sources
arXiv2018

Vibrational modes of Q-balls

We study linear perturbations of classically stable Q-balls in theories admitting analytic solutions. Although the corresponding boundary value problem is non-Hermitian, the analysis of perturbations can also be performed analytically in certain regimes. We show that in theories with the flat potential, large Q-balls possess soft excitations. We also find a specific vibrational mode for Q-balls with a near-critical charge, where the perturbation theory for excitations can be developed. Comparing with the results on stability of Q-balls provides additional checks of our analysis.

hep-th↗
arXiv2016

Q-holes

We consider localized soliton-like solutions in the presence of a stable scalar condensate background. By the analogy with classical mechanics, it can be shown that there may exist solutions of the nonlinear equations of motion that describe dips or rises in the spatially-uniform charge distribution. We also present explicit analytical solutions for some of such objects and examine their properties.

hep-th↗
arXiv2014

Investigation of Q-tubes stability using the piecewise parabolic potential

We analyze the classical stability of Q-tubes --- charged extended objects in $(3+1)$-dimensional complex scalar field theory. Explicit solutions were found analytically in the piecewise parabolic potential. Our choice of potential allows us to construct a powerful method of stability investigation. We check that in the case of the zero winding number $n=0$, the previously known stability condition $\partial^2E/\partial Q^2<0$ for Q-balls is fulfilled. However, in the case $n\geq 1$, we find a continuous family of instabilities. Our result has an analogy with the theory of superconductivity of the second type, in which the vortex with $n>1$ becomes unstable towards the decay into the $n$ vortices with the single winding number.

hep-th↗
arXiv2012

Heavy-meson physics and flavour violation with a single generation

We study flavour-violating processes which involve heavy B- and D-mesons and are mediated by Kaluza-Klein modes of gauge bosons in a previously suggested model where three generations of the Standard Model fermions originate from a single generation in six dimensions. We find the bound on the size R of the extra spatial dimensions 1/R>3.3 TeV, which arises from the three-body decay B_s to K mu e. Due to the still too low statistics this bound is much less stringent than the constraint arising from K to mu e, 1/R>64 TeV, which was found in a previous work (Frere et al., JHEP, 2003). Nevertheless, we argue that a clear signature of the model would be an observation of K to mu e and B_s to K mu e decays without observations of other flavour and lepton number changing processes at the same precision level.

hep-ph↗