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O. V. Teryaev

Publications and source records attributed to O. V. Teryaev.

At least 109 records · Page 6Linked to original sources
arXiv2009

Dispersive Approach to Abelian Axial Anomaly, Mixing of Pseudoscalar Mesons and Symmetries

We suggest a rigorous generalization of the pseudoscalar mesons mixing description in SU(3) basis. It is shown that the appearance of extra massive state nicknamed in the paper as glueball is unavoidable in any scheme with more than one angle. In this framework we develop the dispersive approach to Abelian axial anomaly of isoscalar non-singlet current. Combining it with the analysis of experimental data of charmonium radiative decays ratio we get the number of quite strict constraints for mixing parameters. Our analysis favors the equal values of axial currents coupling constants which may be considered as a manifestation of SU(3) symmetry and possible violation of chiral symmetry based predictions.

hep-ph↗
arXiv2009

Insights on non-perturbative aspects of TMDs from models

Transverse momentum dependent parton distribution functions are a key ingredient in the description of spin and azimuthal asymmetries in deep-inelastic scattering processes. Recent results from non-perturbative calculations in effective approaches are reviewed, with focus on relations among different parton distribution functions in QCD and models.

hep-ph↗
arXiv2009

Diffractive production of chi(c)(0+,1+,2+) mesons at LHC, Tevatron and RHIC

We consider exclusive double diffractive production of scalar χ_c(0^+), axial-vector χ_c(1^+) and tensor χ_c(2^+) charmonia in proton-(anti)proton collisions at different energies. The corresponding amplitudes for these processes are derived within the k_t-factorisation approach and the corresponding cross section is calculated with different unintegrated gluon distribution functions (UGDFs) known from the literature. We compare exclusive production of all charmonium states χ_c(0^+), χ_c(1^+) and χ_c(2^+) including branching fraction for radiative J/Ψ+ γdecay channel. Corresponding experimental consequences are discussed.

hep-ph↗
arXiv2009

Photon-photon collision: ambiguity and duality in QCD factorization theorem

We discuss duality in ``two-photon''-like processes in the scalar $φ^3_E$ model and also in the process $γ^*γ\toππ$ in QCD. Duality implies the equivalence between two distinct nonperturbative mechanisms. These two mechanisms, one involving a twist-3 Generalized Distribution Amplitude, the other employing a leading-twist Transition Distribution Amplitude, are associated with different regimes of factorization. In the kinematical region, where the two mechanisms overlap, duality is observed for the scalar $φ^3_E$ model, while in the QCD case the appearance of duality turns out to be sensitive to the particular nonperturbative model applied and can, therefore, be used as a tool for selecting the most appropriate one.

hep-ph↗
arXiv2009

Thermal Effects for Quark and Gluon Distributions in Heavy-Ion Collisions

In-medium effects for distributions of quarks and gluons in central A+A collisions are considered. We suggest a duality principle, which means similarity of thermal spectra of hadrons produced in heavy-ion collisions and inclusive spectra which can be obtained within the dynamic quantum scattering theory. Within the suggested approach we show that the mean square of the transverse momentum for these partons grows and then saturates when the initial energy increases. It leads to the energy dependence of hadron transverse mass spectra which is similar to that observed in heavy ion collisions.

nucl-th↗
arXiv2009

Elastic double diffractive production of axial-vector χ_c(1^{++}) mesons and the Landau-Yang theorem

We discuss exclusive elastic double diffractive axial-vector χ_c(1^{+}) meson production in proton-antiproton collisions at the Tevatron. The amplitude for the process is derived within the k_t-factorisation approach with unintegrated gluon distribution functions (UGDFs). We show that the famous Landau-Yang theorem is not applicable in the case of off-shell gluons. Differential cross sections for different UGDFs are calculated. We compare exclusive production of χ_c(1^+) and χ_c(0^+). The contribution of χ_c(1^+) to the J/Ψ+ γchannel is smaller than that of the χ_c(0^+) decay, but not negligible and can be measured. The numerical value of the ratio of the both contributions is almost independent of UGDFs modeling.

hep-ph↗
arXiv2009

Transverse momentum dependent distribution functions in a covariant parton model approach with quark orbital motion

Transverse parton momentum dependent distribution functions (TMDs) of the nucleon are studied in a covariant model, which describes the intrinsic motion of partons in terms of a covariant momentum distribution. The consistency of the approach is demonstrated, and model relations among TMDs are studied. As a byproduct it is shown how the approach allows to formulate the non-relativistic limit.

hep-ph↗
arXiv2009

Generalized Parton Distributions and Description of Electromagnetic and Graviton form factors of nucleon

The new parameterization of the generalized parton distributions t-dependence is proposed. It allows one to reproduce sufficiently well the electromagnetic form factors of the proton and neutron at small and large momentum transfer. The description of the data obtained by the Rosenbluth method and the polarization method are compared. The results obtained by the latter method are shown to be compatible with the correspondent neutron data. The impact parameter dependence of the neutron charge density is examined. The quark contributions to gravitational form factors of the nucleons are obtained.

hep-ph↗
arXiv2008

Duality between different mechanisms of QCD factorization in γ^*γcollisions

We study the phenomenon of duality in hard exclusive reactions to which QCD factorization applies. Considering "two-photon"-like processes in the scalar $ϕ^3_E$ model and also hadron-pair production from the collisions of a real (transversely polarized) and a highly virtual, longitudinally polarized, photon in QCD, we identify two regimes of factorization each of them associated with a distinct nonperturbative mechanism. One mechanism involves twist-3 Generalized Distribution Amplitudes, whereas the other one employs leading-twist Transition Distribution Amplitudes. In the case of the scalar $ϕ^3_E$ model, we find duality in that kinematical region where the two mechanisms overlap. In the QCD case, the appearance of duality is sensitive to the particular nonperturbative model applied and can, therefore, be used as an additional adjudicator.

hep-ph↗
arXiv2008

The pretzelosity distribution function and intrinsic motion of the constituents in nucleon

The pretzelosity distribution function $h_{1T}^\perp$ is studied in a covariant the quark-parton model which describes the structure of the nucleon in terms of 3D quark intrinsic motion. This relativistic model framework supports the relation between helicity, transversity and pretzelosity observed in other relativistic models {\sl without} assuming SU(6) spin-flavor symmetry. Numerical results and predictions for SIDIS experiments are presented.

hep-ph↗
arXiv2008

Duality and Factorization Theorem in QCD

We find that in "two-photon"-like processes in the scalar $φ^3_E$ model and also in hadron-pair production arising from the collisions of a real (transversely polarized) and a highly virtual, longitudinally polarized, photon in QCD, there is duality between two distinct nonperturbative mechanisms. These two mechanisms, one involving a twist-3 Generalized Distribution Amplitude, the other employing a leading-twist Transition Distribution Amplitude, are associated with different regimes of factorization. In the kinematical region, where the two mechanisms overlap, duality is observed for the scalar $φ^3_E$ model, while in the QCD case the appearance of duality turns out to be sensitive to the particular nonperturbative model applied and can, therefore, be used as a tool for selecting the most appropriate one.

hep-ph↗
arXiv2008

Dispersive Approach to Abelian Axial Anomaly and $η-η'$ Mixing

We investigate what can be learnt about the $η$ -$η'$ mixing by means of dispersive representation of axial anomaly. We show that our method leads to the strong bounds for the $η-η'$ mixing angle: $θ= -15.3^o \pm 1^o$. Moreover, our result manifests also a dramatic dependence of the width $Γ_{η\to 2γ}$ on the mixing angle $θ$. This property explains how the relatively small mixing strongly effects the decay width.

hep-ph↗
arXiv2008

Gravimagnetic nucleon form-factors in the impact parameter representation

In the framework of the new t-dependence of the General Parton Distributions (GPDs), which reproduce the electromagnetic form factors of the proton and neutron at small and large momentum transfer, the gravitational form factors of the nucleons and a separate contribution of the quarks to them are obtained.

hep-ph↗
arXiv2008

Dispersion relations and QCD factorization in hard reactions

We study analytical properties of the hard exclusive process amplitudes. We found that QCD factorization for deeply virtual Compton scattering and hard exclusive vector meson production results in the subtracted dispersion relation with the subtraction constant determined by the Polyakov-Weiss $D$-term.

hep-ph↗
arXiv2007

Generalized Parton Distrbutions and Nucleon Form Factors

The Dirac and Pauli form factors of the proton and neutron are obtained in the framework of the generalized parton distributions (GPDs) with some simple momentum transfer dependence. It is shown that both sets of the existing experimental data of the form factors, obtained by the Rosenbluth and polarization transfer, can be described by changing only the slope of the GPDs $E$. The description of neutron form factors is substantially better when the proton data obtained by the studies of polarization transfer are used.

hep-ph↗
arXiv2007

Dispersion relations and subtractions in hard exclusive processes

We study analytical properties of the hard exclusive processes amplitudes. We found that QCD factorization for deeply virtual Compton scattering and hard exclusive vector meson production results in the subtracted dispersion relation with the subtraction constant determined by the Polyakov-Weiss $D$-term. The relation of this constant to the fixed pole contribution found by Brodsky, Close and Gunion and defined by parton distributions is proved, while its manifestation is spoiled by the small $x$ divergence. The continuation to the real photons limit is considered and the numerical correspondence between lattice simulations of $D$-term and low energy Thomson amplitude is found.

hep-ph↗
arXiv2007

Equivalence principle and experimental tests of gravitational spin effects

We study the possibility of experimental testing the manifestations of equivalence principle in spin-gravity interactions. We reconsider the earlier experimental data and get the first experimental bound on anomalous gravitomagnetic moment. The spin coupling to the Earth's rotation may also be explored at the extensions of neutron EDM and g-2 experiments. The spin coupling to the terrestrial gravity produces a considerable effect which may be discovered at the planned deuteron EDM experiment. The Earth's rotation should also be taken into account in optical experiments on a search for axionlike particles.

gr-qc↗