arXiv subjects

Michael Kuchiev

Publications and source records attributed to Michael Kuchiev.

14 recordsLinked to original sources

arXiv2015

Enhanced creation of high energy particles in colliding laser beams

The creation of particles by two colliding strong laser beams is considered. It is found that the electron-positron pairs created in the laser field via the Schwinger mechanism may recollide after one or several oscillations in the field. Their collision can take place at high energy, which the pair gains from the field. As a result, high energy gamma quanta can be created by inelastic scattering or annihilation of the pair. Moreover, heavy particles such as muon pairs may also be created via the annihilation $e^+ + e^-\rightarrow μ^+ + μ^- $. The probability of $e^-e^+$ collision is greatly enhanced due to a strong alignment of the electron and positron momenta with the electric field. The found muon creation rate exponentially exceeds the rate predicted by the direct Schwinger mechanism for muons, while the photon creation rate exponentially exceeds photon emission due to the fermion oscillation.

hep-ph↗

arXiv2015

High energy photon production in strong colliding laser beams

The collision of two intense, low-frequency laser beams is considered. The $e^-e^+$ pairs created in this field are shown to exhibit recollisions, which take place at high energy accumulated due to the wiggling of fermions. The resulting $e^-e^+$ annihilation produces high energy photons, or heavy particles. The coherent nature of the laser field provides strong enhancement of the probability of these events. Analytical and numerical results are outlined.

hep-ph↗

arXiv2014

Fermions in energon field

The behavior of fermions in the gauge field created by the energon, a recently found classical solution of the non-Abelian gauge theory, is considered. The spectrum of fermions is evaluated explicitly for the case when parameters governing the energon are chosen to make this solution look similar to the chain of well separated instantons and anti-instantons. The zero eigenvalue in the spectrum of the Dirac equation is found. The role of a specific discrete symmetry, which distinguishes the energon, is discussed.

hep-th↗

arXiv2011

Two heavy fermions bound via Higgs boson exchange

A system of two heavy fermions, leptons or quarks of the fourth generation, which are bound together via the Higgs boson exchange is studied. The conventional Yukawa-type interaction produced by this exchange is accompanied by several important corrections. We derived the Hamiltonian, which describes the correction arising from the retardation (compare the Breit correction in QED); we also calculated the relativistic and radiative corrections. The Higgs-induced bound state appears for the fermion mass m>m_{cr} \approx 500 GeV. When the long-range Coulomb interaction or the gluon exchange are included, the bound states exist for any mass, but the Higgs exchange drastically increases the binding energy of these states when m is approaching m_{cr}. In the region m>m_{cr} the gluon exchange gives a sizable correction to the Higgs induced binding energy. This correction greatly exceeds typical binding energies in the states produced via the gluon exchange only. The possibility of detection of the considered bound states at LHC is discussed.

hep-ph↗

arXiv2011

Simple look at supersymmetric N=2 gauge theory with arbitrary gauge group

A new discrete symmetry is shown to govern and simplify low-energy properties of the supersymmetric N=2 gauge theory with an arbitrary gauge group. Each element of the related symmetry group S_r, r being the rank of the gauge group, represents a permutation of r electric charges available in the theory accompanied by a concurrent permutation of r monopoles, provided the sets of charges and monopoles are chosen properly. The superpotential is symmetric under S_r. This symmetry strongly manifests itself for the degenerate case; when the masses of r electric charges are chosen to be equal, then the masses of r monopoles are necessarily degenerate as well, and vice versa. This condition uniquely defines the vital for the theory VEV of the scalar field, which makes all monopoles massless.

hep-th↗

arXiv2011

Discrete symmetry in supersymmetric N=2 gauge theory

A new discrete symmetry group, which governs low-energy properties of the supersymmetric N=2 gauge theory is found. Each element of this group S_r, r being the rank of the gauge group, represents a permutation of r electric charges available in the theory accompanied by a simultaneous permutation of r monopoles, provided the sets of charges and monopoles are chosen properly. Properties of the theory are strongly influenced by S_r; if the central charges (and masses) of r monopoles are degenerate, then the central charges (and masses) of r electric charges are also necessarily degenerate, and vice versa. This condition uniquely defines the vital value of the VEV of the scalar field, at which all monopoles are massless. The general theoretical discussion is illustrated by a model, which generalizes the Seiberg-Witten treatment of the supersymmetric N=2 gauge theory for an arbitrary gauge group.

hep-th↗

arXiv2010

Supersymmetric N=2 gauge theory with arbitrary gauge group

A new universal model to implement the Seiberg-Witten approach to low-energy properties of the supersymmetric N=2 gauge theory with an arbitrary compact simple gauge group, classical or exceptional, is suggested. It is based on the hyperelliptic curve, whose genus equals the rank of the gauge group. The weak and strong coupling limits are reproduced. The magnetic and electric charges of light dyons, which are present in the proposed model comply with recent predictions derived from the general properties of the theory. The discrete chiral symmetry is implemented, the duality condition is reproduced, and connections between monodromies at weak and strong coupling are established. It is found that the spectra of monopoles and dyons are greatly simplified when vectors representing the scalar and dual fields in the Cartan algebra are aligned along the Weyl vector. This general feature of the theory is used for an additional verification of the model. The model predicts the identical analytic structures of the coupling constants for the theories based on the SU(r+1) and Sp(2r) gauge groups.

hep-th↗

arXiv2009

Semiclassical solution for Yang-Mills field with given energy

A new classical solution for the Yang-Mills theory in which the Euclidean energy plays a role of a parameter is discussed. The instanton and sphaleron are shown to be particular examples of this more general solution. The energy parameter for them takes on special values, which are zero and sphaleron mass for the instanton and sphaleron, respectively. The solution is employed to describe the tunneling process, which is accompanied by a variation of the topological charge. A range of temperatures, where the new solution makes this tunneling more effective than the known mechanisms based on the instanton, caloron or sphaleron is found.

hep-th↗

arXiv2009

Classical paths for Yang-Mills field with fixed energy

A new classical solution for the SU(2) Yang-Mills theory, in which the Euclidean energy plays a role of a parameter is found. A correspondence between this solution and the known selfdual multi-instanton configuration, which has the topological charge N, is discussed, the number of parameters governing the new solution is found to be 8N+1. For negative energies the new solution is periodic in Euclidean time, for positive energies it exhibits the effect of localization, which states that the solution is completely described within a finite interval of time, for zero energy the found solution is reduced to a selfdual one.

hep-th↗

arXiv2008

Light bound states of heavy fermions

In the Standard Model, a group of heavy fermions, e.g. top quarks, can collectively strongly affect the Higgs field and create relatively long-lived bound states. If there exist new generations of fermions with masses beyond 1 TeV, strong binding of several of them can make them lighter than even a single heavy fermion. Using the mean field approximation we find multi-fermion states with masses M ~ 5 v N^{1/2} ~ 1.2 N^{1/2} TeV, with N=2,3... being the total number of heavy fermions bound together, and v=246 GeV the Higgs VEV. The experimental search for multi-fermions within the range of energies 2-3 Tev would either discover them, or suggest absence of new Standard Model fermions with larger masses. Possible implications related to multi-top states and baryonic asymmetry of the Universe are discussed.

hep-ph↗

arXiv2008

On bound states of multiple t-quarks due to Higgs exchange

Froggatt, Nielsen et al suggested that the Higgs boson exchange between top quarks produces enough attraction to generate their multiple bound states. Furthermore they claimed that the system of 6 top and 6 anti-top quarks is bound so strongly that the binding energy nearly compensates the masses of t-quarks, making it very light. We calculated the energy of such states more accurately, variationally and by self-consistent mean field approximation, and found that these state are weakly bound for massless Higgs boson and unbound with the account for its mass.

hep-ph↗

arXiv2008

Vector Bosons in Strong Fields

The Coulomb problem for charged massive vector bosons is known to be unstable, the boson falls on the Coulomb center. It is shown that when the charge of the Coulomb center is smeared over a small but finite volume, then instead of the fall there appears a large series of bound states localized inside the volume containing the Coulomb charge. It is shown also that the fall on the Coulomb center is completely suppressed, when the conventional QED vacuum polarization is taken into account.In gauge theories (SU(2), Standard Model) the renormalizability of a theory may be insufficient to guarantee an absence of the wave function collapse. Another interesting feature: the density of charge of vector bosons can have a ``wrong'' sign.

hep-ph↗

arXiv2006

Charge density of a positively charged vector boson may be negative

The charge density of vector particles, for example W, may change sign. The effect manifests itself even for a free propagation; when the energy of the W-boson is higher than sqrt{2}m and the standing-wave is considered the charge density oscillates in space. The charge density of W also changes sign in close vicinity of a Coulomb center. The dependence of this effect on the g-factor for an arbitrary vector boson, for example rho-meson, is discussed. An origin of this surprising effect is traced to the electric quadrupole moment and spin-orbit interaction of vector particles. Their contributions to the current have a polarization nature. The charge density of this current, rho = -\nabla \cdot P, where P is an effective polarization vector that depends on the quadrupole moment and spin-orbit interaction, oscillates in space, producing zero contribution to the total charge.

hep-ph↗

arXiv2006

When renormalizability is not sufficient: Coulomb problem for vector bosons

The Coulomb problem for vector bosons W incorporates a known difficulty; the boson falls on the center. In QED the fermion vacuum polarization produces a barrier at small distances which solves the problem. In a renormalizable SU(2) theory containing vector triplet (W^+,W^-,gamma) and a heavy fermion doublet F with mass M the W^- falls on F^+, to distances r ~ 1/M, where M can be made arbitrary large. To prevent the collapse the theory needs additional light fermions, which switch the ultraviolet behavior of the theory from the asymptotic freedom to the Landau pole. Similar situation can take place in the Standard Model. Thus, the renormalizability of a theory is not sufficient to guarantee a reasonable behavior at small distances for non-perturbative problems, such as a bound state problem.

hep-ph↗