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M. I. Vyazovsky

Publications and source records attributed to M. I. Vyazovsky.

At least 19 recordsLinked to original sources

The Regge-Gribov model with odderons

The Regge-Gribov model describing interacting pomerons and odderons is proposed with triple reggeon vertices taking into account the negative signature of the odderon. Its simplified version with zero transverse dimensions is first considered. No phase transition occurs in this case at the intercept crossing unity. This simplified model is studied without more approximations by numerical techniques. The physically relevant model in the two-dimensional transverse space is then studied by the renormalization group method in the single loop approximation. The pomeron and odderon are taken to have different bare intercepts and slopes. The behaviour when the intercepts move from below to their critical values compatible with the Froissart limitation is studied. Five real fixed points are found with singularities in the form of non-trivial branch points indicating a phase transition as the intercepts cross unity. The new phases, however, are not physical, since they violate the projectile-target symmetry. In the vicinity of fixed points the asymptotical behaviour of Green functions and elastic scattering amplitude is found under Glauber approximation for couplings to participants.

hep-th

On the reggeon model with the pomeron and odderon: singularities with non-zero masses

The Regge-Gribov model of the pomeron and odderon in the non-trivial transverse space is studied by the renormalization group technique in the single loop approximation. The pomeron and odderon are taken to have different bare intercepts and slopes. The behaviour when the intercepts move from below to their critical values compatible with the Froissart limitation is studied. The singuarities in the form of non-trivial branch points indicating a phase transition are found in the vicinity of five fixed points found in the previous publication. Since new phases violate the projectile-target symmetry the model is found non-physical for the bare intercepts above their critical value.

hep-th

The reggeon model with the pomeron and odderon: renormalization group approach

The Regge-Gribov model of the pomeron and odderon in the non-trivial transverse space is studied by the renormalization group technique. The single loop approximation is adopted. Five real fixed points are found and the high-energy behaviour of the propagators is correspondingly calculated. As without odderon, the asymptotic is modulated by logarithms of energy in certain rational powers. Movement of coupling constants away from the fixed points is investigated both analytically (close to the fixed points) and numerically (far away). In the former case attraction occurs only in restricted domains of initial coupling constants. More generally in one third of the cases the coupling constants instead grow large indicating the breakdown of the single loop approximation.

hep-th

Local one-dimensional reggeon model of the interaction of several pomerons

We consider the one-dimensional local reggeon theory describing the leading pomeron with the conformal spin $l=0$ and two subdominant pomerons with $l=\pm 2$. The dependence of the propagators of pomerons and the $hA$ amplitude on rapidity are found numerically by integrating the evolution equation.

hep-ph

Local one-dimensional reggeon model of the interaction of pomerons and odderons

We propose the one-dimensional reggeon theory describing local pomerons and odderons. It generalizes the well-known one-dimensional theory of pomerons (the Gribov model) and includes only triple interaction vertices. The proposed theory is studied by numerical methods: the one-particle pomeron and odderon propagators and the pA amplitude are found as functions of rapidity by integrating the evolution equation.

hep-ph

Deconfinement temperature in AdS/QCD from the spectrum of scalar glueballs

We scrutinize various holographic estimations of the deconfinement temperature within the bottom-up AdS/QCD models. A special emphasis is put on the recent idea of isospectral potentials in the holographic approach. It is demonstrated that different models from an isospectral family (i.e., the models leading to identical predictions for the spectrum of hadrons with fixed quantum numbers) result in different predictions for the deconfinement temperature. This difference is found to be quite small in the scalar glueball channel but very large in the vector meson channel which is often used for fixing parameters of holographic models. The observed stability in the former case clearly favors the choice of the glueball channel for thermodynamic predictions in AdS/QCD models, with the scalar glueball trajectory being taken from lattice simulations and used as a basic input in improved versions of the Soft Wall holographic model.

hep-ph

Gluon emission at small longitudinal momenta in the QCD effective action approach

In the framework of the QCD effective action the vertices of gluon emission in interaction of reggeons are studied in the limit of small longitudinal momenta of the emitted gluon. It is found that the vertices drastically simplify in this limit so that the gluon becomes emitted from a single reggeon coupled to the projectile and target via multireggeon vertices. Contribution from this kinematical region is studied for double and 2x2 elementary collisions inside the composite projectile and target.

hep-ph

Diffractive scattering on the deuteron projectile in the NLO: triple interaction of reggeized gluons

High-mass diffractive production of protons on the deuteron target is studied in the next-to-leading order (NLO) of the perturbative QCD in the BFKL approach. The non-trivial part of the NLO contributions coming from the triple interactions of the exchanged reggeons is considered. Analytic formulas are presented and shown to be infrared free and so ready for practical calculation.

hep-ph

Reggeon-gluon vertices with Ward identities

Ward identities for reggeons are studied in the framework of effective action approach to the QCD in Regge kinematics. It is shown that they require introduction of new contributions not present in the reggeon diagrams initially. Application to vertices RR$\to$RP and RR$\to$RRP are considered and diagrams which have to be added to the QCD ones are found.

hep-ph

Gluon emission in interaction of two reggeons

The vertex is constructed for gluon production in interaction of two reggeons coupled to projectiles and two reggeons coupled to targets. The vertex can be used to build cross-sections for collisions of two pairs of nucleons in AA scattering. Transversality of the constructed vertex is demonstrated as well as its good behaviour at large longitudinal momenta necessary for applications. Poles at zero values of longitudinal momenta are discussed and it is found that they remain in the amplitudes unlike in the case of a single projectile.

hep-ph

On the application of the effective action approach to amplitudes with reggeon splitting

Application of the effective action approach to amplitudes with loop integration is studied for collisions on two and three centers with possible gluon emission. A rule is formulated for the integration around pole singularities in the induced vertices which brings the results in agreement with the QCD. It is demonstrated that the amplitudes can be restored from the purely transverse picture by introducing the standard Feynman propagators for intermediate gluons and quarks.

hep-ph

Gluon production in the Lipatov effective action formalism

Gluon production on two scattering centers is studied in the formalism of reggeized gluons. Different contributions to the inclusive cross-section are derived with the help of the Lipatov effective action. The AGK relations between these contributions are established. The found inclusive cross-section is compared to the one in the dipole picture and demonstrated to be the same.

hep-ph

Production of a gluon with the exchange of three reggeized gluons in the Lipatov effective action approach

In the Regge kinematics the amplitude for gluon production off three scattering centers is found in the Lipatov effective action technique. The vertex for gluon emission with the reggeon splitting in three reggeons is calculated and its transversality is demonstrated. It is shown that in the sum of all contributions terms containing principal value singularities are cancelled and substituted by the standard Feynman poles. These results may be used for calculation of the inclusive cross-section for gluon production on two nucleons in the nucleus.

hep-ph

On the inclusive gluon production in the Lipatov effective action formalism

The process of gluon production in quark-nucleus collisions is studied in the framework of Lipatov's effective action formalism. The relevant simplifications and rules for longitudinal integrations are discussed in detail. The results obtained with the help of these rules correspond to the purely transversal formalism based on effective vertices in the transversal space.

hep-ph

Gluon production on two centers and the effective action approach

Application of the effective action formalism is studied for processes in which the reggeons may split. It is shown that the gluon production on two centers is described by the contribution of the Reggeon-to-two-Reggeons-plus-Particle vertex supplemented by certain singular contributions from the double gluon exchange. The rules for longitudinal integrations are established from the comparison to perturbative QCD amplitude. Convenient expressions for application to the inclusive gluon production are derived.

hep-ph

Production of two gluons in the Lipatov effective action formalism

The one-loop diffractive amplitude for emission of two real gluons with widely different rapidities is studied in the Lipatov effective action formalism. It is shown that after integration over longitudinal momenta in the loop the resulting expression coincides with the one obtained by the Lipatov-Bartels formalism in transversal space provided the same prescription is used to exclude divergent contributions as previously proposed for emission of a single real gluon.

hep-ph

Origin of the second coherent peak in the dynamical structure factor of an asymmetric spin-ladder

Appearance of the second coherent peak in the dynamical structure factor of an asymmetric spin ladder is suggested. The general arguments are confirmed by the first order (with respect to the asymmetry) calculation for a spin ladder with singlet-rung ground state. Basing on this result a new interpretation is proposed for the inelastic neutron scattering data in the spin gap compound CuHpCl.

cond-mat.str-el