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Nikolai Kochelev

Publications and source records attributed to Nikolai Kochelev.

At least 19 recordsLinked to original sources
arXiv2017

Single-spin asymmetries in SIDIS induced by anomalous gluon-quark and photon-quark couplings

We calculate the contribution of the non-perturbative Pauli couplings in the quark-photon and quark-gluon vertices to the single-spin asymmetries (SSAs) in semi-inclusive deep inelastic scattering (SIDIS). We describe the nucleon using the spectator model with scalar and axial-vector diquarks. Both of the new couplings can cause the helicity flip of the struck quark. The helicity flip and the rescattering induced by the non-perturbative gluon exchange between the struck quark and diquark lead to the SSAs. Their azimuthal dependencies are the same as that usually ascribed to the Collins and Sivers effects. Our numerical results, based on the instanton model for the QCD vacuum, show that the non-perturbative quark-gluon and quark-photon interactions have a strong influence on these asymmetries.

hep-ph↗
arXiv2017

Exotic glueball $0^{\pm -}$ states in QCD Sum Rules

The lowest dimension three-gluon currents that couple to the exotic $0^{\pm-}$ glueballs have been constructed using the helicity formalism. Based on the constructed currents, we obtain new QCD SRs that have been used to extract the masses and the decay constants of the scalar exotic $0^{\pm-}$ glueballs. We estimate the masses for the scalar state and for the pseudoscalar state to be ${m_+=9.8^{+1.3}_{-1.4}}$ GeV and $m_-=6.8^{+1.1}_{-1.2}$ GeV.

hep-ph↗
arXiv2017

Gluonic Distribution in the Constituent Quark and Nucleon Induced by the Instantons

Instanton effects can give large contribution to strong interacting processes, especially at the energy scale where perturbative QCD is no longer valid. However instanton contribution to the gluon contribution in constituent quark and nucleon has never been calculated before. Based on both the constituent quark picture and the instanton model for QCD vacuum, we calculate the unpolarized and polarized gluon distributions in the constituent quark and in the nucleon for the first time. We find that the pion field plays an important role in producing both the unpolarized and the polarized gluon distributions.

hep-ph↗
arXiv2017

The Pauli Form Factor of Quark and Nontrivial Topological Structure of the QCD

We calculate the electromagnetic Pauli form factor of quark induced by the nontrivial topological fluctuations of QCD vacuum called instantons. It is shown that such contribution is significant. We discuss the possible implications of our result in the photon-hadron reactions and in the dynamics of quark-photon interactions in the dense/hot quark matter.

hep-ph↗
arXiv2017

Is the exotic $0^{--}$ glueball a pure gluon state ?

We present a new calculation of the mass and width of the exotic $0^{--}$ glueball in the framework of the QCD sum rules. We next construct a new current which couples to a pure $0^{--}$ gluon state and derive consistent and stable sum rules. A previously used current in this approach was shown to be inconsistent. We obtain for this state a mass $M_G=6.3^{+0.8}_{-1.1}$ GeV and an upper limit for the total width $Γ_G\leq 235$ MeV. These values can be used as an important guide for the experimental search of this exotic state. We argue that the mixing of this glueball state with $0^{--}$ tetraquark is very small. Therefore, the exotic $0^{--}$ glueball can be considered as a pure gluon state.

hep-ph↗
arXiv2017

XYZ mesons and Glueballs: effects of the quark-gluon mixing

We present the new developments in the physics of XYZ mesons and glueballs and discuss the connection between properties of the $XYZ$ mesons and glueballs, and the structure of the QCD vacuum. It is shown that the mixing between quark and gluon degree of freedoms induced by the nontrivial topological structure of the QCD vacuum might affect strongly the properties of the exotic hadrons. A new interpretation of the $XYZ$ mesons as the mixing between radial excitations of light quark-antiquark systems and states with heavy quark content is suggested. We introduce also a new mechanism of quarkonia production in hadron-hadron collisions coming from the mixing of light and heavy quark sectors of QCD. This mechanism is based on the nontrivial topological structure of the QCD vacuum and might explain the polarization puzzle in inclusive $J/Ψ$ production in high energy reactions. The possibility of big changes of the scalar and pseudoscalar glueball masses in the hot gluonic plasma is established and their consequences in the phase structure of QCD analyzed.

hep-ph↗
arXiv2016

Glueball dynamics in the hot plasma

We discuss the glueball contribution to the equation of state (EoS) of hot gluon matter below and above $T_c$. It is shown that the strong changing of masses of scalar and pseudoscalar glueballs near $T_c$ plays very important role in the thermodynamics of $SU(3)$ gauge theory. In particular, we give the arguments that these glueballs become massless at $T_G\approx 1.1T_c$ and this phenomenon is crucial in understanding of the mystery in the behavior of trace anomaly founded in the lattice calculation.

hep-ph↗
arXiv2016

Gluonic Structure of the Constituent Quark

Based on both the constituent quark picture and the instanton model for QCD vacuum, we calculate the unpolarized and polarized gluon distributions in the constituent quark and in the nucleon. Our approach consists of the two main steps. At the first step, we calculate the gluon distributions inside the constituent quark generated by the perturbative quark-gluon interaction, the non-perturbative quark-gluon interaction, and the non-perturbative quark-gluon-pion anomalous chromomagnetic interaction. The non-perturbative interactions are related to the existence of the instantons, strong topological fluctuations of gluon fields, in the QCD vacuum. At the second step, the convolution model is applied to derive the gluon distributions in the nucleon. A very important role of the pion field in producing the unpolarized and the polarized gluon distributions in the hadrons is discovered. We discuss a possible solution of the proton spin problem.

hep-ph↗
arXiv2015

Non-perturbative collisional energy loss of heavy quarks in quark-gluon plasma

We suggest a new mechanism for the energy loss of fast heavy quarks in quark-gluon plasma. This mechanism is based on pion production caused by the anomalous chromomagnetic quark-gluon-pion interaction induced by strong topological fluctuations of the gluon fields represented by instantons. We found that this mechanism gives a considerable contribution to the collisional energy loss of a heavy quark in quark-gluon plasma, which shows a nontrivial role of nonperturbative phenomena in strongly interacting quark-gluon plasma.

hep-ph↗
arXiv2015

Anomalous pion production induced by nontrivial topological structure of QCD vacuum

A new mechanism for the pion production in the high energy reactions is suggested. It is related to the possibility for direct production of the pions induced by instantons, topologically nontrivial gluonic excitations of QCD vacuum. This mechanism does not require any fragmentation functions for production of pseudoscalar mesons in high energy reactions with hadrons. We calculate the contribution of a new mechanism to the inclusive $π^0$-meson production in high energy proton-proton collision. It is shown that it gives the dominated contribution to the inclusive cross-sections in the few GeV region for the transverse momentum of final pion. We discuss the possible application of a new mechanism to the phenomenon of the large spin effects observed in the numerous high energy reactions.

hep-ph↗
arXiv2015

Ultra-light Glueballs in Quark-Gluon Plasma

We consider the dynamics of the scalar and pseudoscalar glueballs in the Quark-Gluon Plasma (QGP). By using the instanton model for the QCD vacuum we give the arguments that the nonperturbative gluon-gluon interaction is qualitatively different in the confinement and deconfinement phases. Based on this observation it is shown that above $T_c$ the values of the scalar and pseudoscalar glueball masses might be very small. The estimation of the temperature of scale invariance restoration, at which the scalar glueball becomes massless, is given. We also discuss the Bose-Einstein condensation of the glueballs and the superfluidity of the glueball matter in QGP.

hep-ph↗
arXiv2014

Anomalous Quark Chromomagnetic Moment and Dynamics of Elastic Scattering

We estimate the contribution of nonperturbative quark-gluon chromomagnetic interaction to the high energy elastic proton-proton cross section at large momentum transfer. It is shown that this contribution is very large in the accessible kinematic region of the present experiments. We argue that Odderon which is the $P=C=-1$ partner of Pomeron, is governed by the spin-flip component related to the nonperturbative three-gluon exchange induced by the anomalous quark chromomagnetic moment. We discuss the possible spin effects in the elastic proton-proton and proton-antiproton scattering coming from the interference of spin-flip nonperturbative Odderon and nonspin-flip Pomeron exchanges.

hep-ph↗
arXiv2013

Anomalous Quark Chromomagnetic Moment and Single-Spin Asymmetries

We discuss a nonperturbative mechanism for the single-spin asymmetries (SSA) in the strong interaction. This mechanism is based on the existence of a large anomalous quark chromomagnetic moment (AQCM) induced by the nontrivial topological structure of QCD vacuum. Our estimations within the instanton liquid model for QCD vacuum show that AQCM generates very large SSA on the quark level. Therefore, this mechanism can be responsible for the anomalously large SSA observed in different high energy reactions with hadrons.

hep-ph↗
arXiv2012

Non-perturbative QCD effects in $η_c$ and $η_b$ decays into baryons and WIMP scattering off nuclei

In this work we estimate the helicity suppressed decay rates of $η_b$ resonances into baryon pairs due to instanton-induced effects by rescaling the corresponding partial widths of the experimentally measured branching ratios for the $η_c(1S) \to p\bar{p}$ and $η_c(1S) \to Λ\bar(Λ)$ decay modes. Thus we point out that both $η_b(1S) \to p\bar{p}$ and $η_b(1S) \to Λ\bar(Λ)$ channels could be detected at a Super B factory and LHC experiments. Furthermore, we examine related instanton-induced effects on WIMP scattering off nuclei concluding, albeit with large uncertainties, that they might enhance the spin-dependent cross section for a light pseudoscalar Higgs boson mediator, thereby inducing a dependence on the momentum transfer to the recoling nucleus.

hep-ph↗
arXiv2012

Anomalous quark-gluon chromomagnetic interaction and high energy $ρ$-meson electroproduction

It is shown that existence of a large anomalous chromomagnetic moment of quark induced by non-perturbative structure of QCD leads to the additional contribution to exclusive $ρ$-meson electroproduction off proton target. The significant contribution coming from new type of quark-gluon interaction to the $ρ$-meson production cross section for both transversal and longitudinal polarization of virtual photon is found. Such non-perturbative contribution together with conventional perturbative two-gluon exchange allows us to describe the experimental data at low $Q^2$ for transversal polarization. However, in the longitudinal polarization case there is still some discrepancy with the data. The possible source of this deviation is discussed.

hep-ph↗
arXiv2012

Axial anomaly and the delta_{LT} puzzle

The axial anomaly contribution to generalized longitudinal-transverse polarizability $δ_{LT}^{}$ is calculated within Regge approach. It is shown that the contribution from the exchange of the $a_1^{}(1260)$ Regge trajectory is nontrivial and might have the key role to explain the large difference between the predictions of chiral perturbation theory and the experimental data for the neutron $δ_{LT}^{}$. We also present the prediction for the proton $δ_{LT}^{}$, which will be measured at the Thomas Jefferson National Accelerator Facility in near future.

hep-ph↗
arXiv2010

Role of anomalous chromomagnetic interaction in Pomeron and Odderon structures and in gluon distribution

We calculate the contribution arising from nonperturbative quark-gluon chromomagnetic interaction to the high energy total quark-quark cross section and to gluon distributions in nucleon. The estimation obtained within the instanton model of QCD vacuum leads to the conclusion that this type of interaction gives the dominating contribution to the Pomeron coupling with the light quarks and to gluon distribution in light hadrons at small virtualities of quarks and gluons. We argue that the Odderon, which is the $P=C=-1$ partner of Pomeron, is governed by the spin-flip component related to nonperturbative three-gluon exchange induced by anomalous quark-gluon chromomagnetic interaction.

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