arXiv subjects

O. Teryaev

Publications and source records attributed to O. Teryaev.

17 recordsLinked to original sources

arXiv2026

Complementary Approach to Anisotropic Flows in Heavy-Ion Collisions

We introduce a no-reaction-plane (no-RP) method for extracting directed ($v_1$) and elliptic ($v_2$) flows in heavy-ion collisions, which eliminates the need for event-plane reconstruction. %by scanning over fixed test angles and using simple count asymmetries. The method is validated with PHSD model simulations of Au+Au collisions at $\sqrt{s_{NN}} = 9.2$ GeV at freeze-out (for impact parameters $b = 4-8$ fm). We demonstrate that the two asymmetries for each harmonic contribute equally, i.e., $\langle A_{\mathrm{ud}}^2\rangle \approx \langle A_{\mathrm{lr}}^2\rangle$ and $\langle A_1^2\rangle \approx \langle A_2^2\rangle$, so that a single asymmetry measurement suffices for a good flow estimate. Event-by-event comparisons with direct calculations using the true reaction plane yield Pearson correlation coefficients of 0.956 for $v_2$ and 0.834 for $v_1$, confirming that the no-RP method captures flow fluctuations well enough.

nucl-th↗

arXiv2025

Three-dimensional imaging of hadrons with hard exclusive reactions: advances in experiment, theory, phenomenology, and lattice QCD

Generalized Parton Distributions (GPDs) have emerged as a powerful framework for exploring the internal structure of hadrons in terms of their partonic constituents. Over the past three decades, the field has witnessed significant theoretical and experimental advancements. The interpretation of GPDs in impact parameter space offers a vivid three-dimensional visualization of hadron structure, correlating longitudinal momentum and transverse spatial distributions, thereby enabling tomographic imaging of hadrons. Furthermore, the link between GPDs and the matrix elements of the QCD energy-momentum tensor provides access to fundamental properties of hadrons, including spin decomposition and internal pressure distributions. Notably, recent analyses of Deeply Virtual Compton Scattering (DVCS) data have enabled the empirical extraction of the quark pressure profile inside the proton. Motivated by the rapidly evolving experimental landscape, this white paper provides a timely and focused overview of recent developments in GPD theory, phenomenology, and lattice QCD studies. Its scope is shaped by the needs and opportunities of forthcoming experimental programs, and it highlights advances that are particularly relevant for the next generation of dedicated measurements, including the extended Jefferson Lab 12 GeV program and its potential 22 GeV upgrade, J-PARC, COMPASS/AMBER, LHC ultra-peripheral collisions, and the future electron-ion colliders EIC and EicC.

hep-ph↗

arXiv2021

On the physics potential to study the gluon content of proton and deuteron at NICA SPD

The Spin Physics Detector (SPD) is a future multipurpose experiment foreseen to run at the NICA collider, which is currently under construction at the Joint Institute for Nuclear Research (JINR, Dubna, Russia). The physics program of the experiment is based on collisions of longitudinally and transversely polarized protons and deuterons at $\sqrt{s}$ up to 27 GeV and luminosity up to 10$^{32}$ cm$^{-2}$ s$^{-1}$. The SPD will operate as a universal facility for comprehensive study of unpolarized and polarized gluon content of the nucleon, using different complementary probes such as: charmonia, open charm, and prompt photon production processes. The aim of this work is to make a thorough review of the physics objectives that can potentially be addressed at the SPD, underlining related theoretical aspects and discussing relevant experimental results when available. Among different pertinent phenomena particular attention is drawn to the study of the gluon helicity, gluon Sivers and Boer-Mulders functions in the nucleon, as well as the gluon transversity distribution in the deuteron, via the measurement of specific single and double spin asymmetries.

hep-ex↗

arXiv2020

Lepton-pair production in hard exclusive hadron-hadron collisions

We investigate lepton-pair production in hard exclusive hadron-hadron collisions. We consider a double handbag (DH) mechanism in which the process amplitude factorizes in hard subprocesses, qq -> qq gamma* and qg -> qg gamma*, and in soft hadron matrix elements parameterized as generalized parton distributions (GPDs). Employing GPDs extracted from exclusive meson electroproduction, we present predictions for the lepton-pair cross section at kinematics typical for the LHC, NICA and FAIR. It turns out from our numerical studies that the quark-gluon subprocess dominates by far, the quark-quark (antiquark) subprocesses are almost negligible.

hep-ph↗

arXiv2018

On axial current in rotating and accelerating medium

Statistical average of the axial current is evaluated on the basis of the covariant Wigner function. In the resulting formula, chemical potential $μ$, angular velocity $Ω$ and acceleration $a$ enter in combination $μ\pm (Ω\pm ia)/2$. The limiting cases of zero mass and zero temperature are investigated in detail. In the zero-mass limit, the axial current is described by a smooth function only at temperatures higher than the Unruh temperature. At zero temperature, the axial current, as a function of the angular velocity and chemical potential, vanishes in a two-dimensional plane region.

hep-th↗

arXiv2016

Axial anomaly and energy dependence of hyperon polarization in Heavy-Ion Collisions

We address the issue of energy and charge dependence of global polarization of $Λ$ hyperons in peripheral $Au-Au$ collisions recently observed by the STAR collaboration at RHIC. We compare different contributions to the anomalous mechanism relating polarization to vorticity and hydrodynamic helicity in QCD matter. We stress that the suppression of the gravitational anomaly contribution in strongly correlated matter observed in lattice simulations confirms our earlier prediction of rapid decrease of polarization with increasing collision energy. Our mechanism leads to polarization of $\bar Λ$ of the same sign and larger magnitude than the polarization of $Λ$. The energy and charge dependence of polarization is suggested as a sensitive probe of fine details of QCD matter structure.

nucl-th↗

arXiv2016

Analysis of the $e^{+}e^{-}\rightarrowπ^{0}γ$ process using anomaly sum rules approach

The process $e^{+}e^{-}\rightarrowγ^{*}\rightarrow π^{0}γ$ was considered using time-like pion transition form factor, obtained in the approach of the Anomaly Sum Rules(ASR). The total cross section and angular distribution of the process was calculated. As the result of the comparison with the data it was shown that ASR approach provides their good description in the regions far from the pole. Also there was proposed a method allowing to give reasonable description of data in the region of pole within the ASR approach. The strong restrictions for the parameters of the modified ASR approach were obtained.

hep-ph↗

arXiv2015

Parity-odd effects in heavy-ion collisions in the HSD model

Helicity separation effect in non-central heavy ion collisions is investigated using the Hadron-String Dynamics (HSD) model. Computer simulations are done to calculate velocity and hydrodynamic helicity on a mesh in a small volume around the center of the reaction. The time dependence of hydrodynamic helicity is observed for various impact parameters and different calculation methods. Comparison with a similar earlier work is carried out. A new quantity is used to ananlyze particles in the final state. It is used to probe for p-odd effects in the final state.

nucl-th↗

arXiv2011

Quarkonium production in high energy proton-proton and proton-nucleus collisions

We present a brief overview of the most relevant current issues related to quarkonium production in high energy proton-proton and proton-nucleus collisions along with some perspectives. After reviewing recent experimental and theoretical results on quarkonium production in pp and pA collisions, we discuss the emerging field of polarisation studies. Thereafter, we report on issues related to heavy-quark production, both in pp and pA collisions, complemented by AA collisions. To put the work in a broader perspective, we emphasize the need for new observables to investigate quarkonium production mechanisms and reiterate the qualities that make quarkonia a unique tool for many investigations in particle and nuclear physics.

hep-ph↗

arXiv2009

The relevance of positivity in spin physics

Positivity reduces substantially the allowed domain for spin observables. We briefly recall some methods used to determine these domains and give some typical examples for exclusive and inclusive spin-dependent reactions.

hep-ph↗

arXiv1998

Positivity Constraints for off-Forward Parton Distributions

Off-Forward Parton Distributions (OFPD's) are new hadronic objects which may be measured in various exclusive reactions. We derive non-trivial positivity constraints for them that should allow to get extra restrictions for model inputs.

hep-ph↗

arXiv1998

Sum Rules and Positivity Constraints on Nucleon Spin Structure

The spin structure of nucleon at twist 2 and 3 levels is analyzed. The contribution of quark and gluon spins to nucleon spin are Lorentz invariant, while it is not sure for orbital angular momentum. The conserved fractional moments of transversity distribution are considered. The scenario of decoupled total angular momentum, determined predominantly by the unpolarized scattering, is discussed.

hep-ph↗

arXiv1998

Probing partonic structure in gamma* gamma -> pi pi near threshold

Hadron pair production gamma* gamma -> h hbar in the region where the c.m. energy is much smaller than the photon virtuality can be described in a factorized form, as the convolution of a partonic handbag diagram and generalized distribution amplitudes which are new non-perturbative functions describing the exclusive fragmentation of a quark-antiquark pair into two hadrons. Scaling behavior and a selection rule on photon helicity are signatures of this mechanism. The case where h is a pion is emphasized.

hep-ph↗

arXiv1997

Double Spin Asymmetries in Charmonium Hadroproduction at HERA-$\vec N$

We discuss the double spin asymmetries in charmonium hadroproduction with nonzero transverse momenta at fixed target energies, $\sqrt{s}\simeq40$ GeV, within the framework of the factorization approach. It is shown that the color octet contribution is dominant in the asymmetries. The size of the asymmetries and the projected statistical errors in a future option of HERA with longitudinally polarized protons scattering off a polarized target (HERA-$\vec N$) should allow to distinguish between different parametrizations for the polarized gluon distribution in the proton.

hep-ph↗

arXiv1996

Single spin asymmetry for the Drell-Yan process

We calculated the single spin asymmetries for the reaction $P+P(\uparrow)\rightarrow l \overline{l}+X$ in the framework of twist-3 QCD for HERA energies. The necessary imaginary phase is produced by the on-shell contribution of the quark propagator, while the long distance part is analogous to that providing the direct photon asymmetry calculated by J. Qiu and G. Sterman. The asymmetry turns out to be generally of the order percent.

hep-ph↗

arXiv1996

Neutron spin-dependent structure function, Bjorken sum rule, and first evidence for singlet contribution at low x

We perform the isospin decomposition of proton and neutron SLAC data in the region $0.01 \leq x \leq 0.1$. The isovector part is well described by a power behaviour $x^α$, where $α$ leads to the validity of Bjorken sum rule and it is consistent with the power extracted from all previous data using NLO evolution. The isoscalar part behaviour may be interpreted as a partial cancellation between a positive non-singlet contribution and a singlet one strongly negative.

hep-ph↗

arXiv1996

On the Physics Potential of Polarized Nucleon-Nucleon Collisions at HERA

The physics of polarized nucleon--nucleon collisions originating from an internal polarized target in the HERA proton beam is investigated. Based on 240 pb^-1 integrated luminosity at 40 GeV c.m. energy, statistical sensitivities are given over a wide (x_F, p_T) range for a variety of inclusive and exclusive final states. By measuring single spin asymmetries unique information can be obtained on higher twist contributions and their p_T-dependence. From double spin asymmetries in both photon and J/psi production it appears possible to measure the polarized gluon distribution in the range 0.1<x_gluon<0.4 with a good statistical accuracy.

hep-ph↗