arXiv subjects

Anton Karpishkov

Publications and source records attributed to Anton Karpishkov.

13 recordsLinked to original sources

arXiv2024

Associated production of $J/ψ$ and direct photon in the NRQCD and the ICEM using the high-energy factorization

We study the associated $J/ψ$ and direct photon production in the high-energy factorization, as it is formulated in the parton Reggeization approach, using two different models for the hadronization of a heavy quark-antiquark pair into a heavy quarkonium, namely the non-relativistic quantum chromodynamics (NRQCD) and the improved color evaporation model (ICEM). We find essential differences in the predictions for cross-section and transverse momenta spectra obtained using the NRQCD and the ICEM, which can be used to discriminate between these models. Our prediction for cross-sections of the associated $J/ψ$ and direct photon production at the LHC energies slightly overestimates the results obtained early in the next-to-leading order (NLO) calculation in the collinear parton model (CPM). We predict different two-particle correlation spectra in the associated $J/ψ$ and direct photon production which may be of interest for experimental study.

hep-ph↗

arXiv2023

Probing Gluons at the Spin Physics Detector

The Spin Physics Detector (SPD) at the Nuclotron based Ion Collider fAcility (NICA) is a multi-purpose experiment designed to study nucleon spin structure in the three dimensions. With capabilities to collide polarized protons and deuterons with center of mass energy up to 27 GeV and luminosity up to $10^{32} \rm cm^{-2} \ s^{-1}$ for protons (an order of magnitude less for deuterons), the experiment will allow measurements of cross-sections and spin asymmetries of hadronic processes sensitive to the unpolarized and various polarized (helicity, Sivers, Boer-Mulders) gluon distributions inside the nucleons. Results from the SPD will be complementary to the present high energy spin experiments at the RHIC facility or future experiments like the EIC (at BNL) and AFTER (at LHC). SPD will provide data in moderate and large Bjorken-x for much improved global analyses of spin structures of the basic building blocks of Nature. With polarized deuteron collisions, SPD will be the unique laboratory for probing tensor polarized gluon distributions. In addition, there are also possibilities of colliding other light nuclei like Carbon at reduced collision energy and luminosity at the first stage of the experiment.

hep-ex↗

arXiv2022

On transverse single-spin asymmetries in $D$-meson production at the SPD NICA experiment

In the present study we are interested in the Sivers effect in process $p^{\uparrow}p\to DX$. We calculate the transverse single-spin asymmetry (TSSA) of $D$-meson production within two phenomenological models, namely the Generalized Parton Model (GPM) and it's Colour Gauge-Invariant formulation (CGI-GPM), which takes into account the transverse momenta of initial partons. The last one allows us to study process-independent Sivers functions. To predict production cross-section of $D$-mesons we use a fragmentation approach with scale-independent Peterson fragmentation function, taking in mind nonzero masses of $c$-quark and $D$-mesons. Estimates for the TSSAs, as a function of transverse momentum and Feynman variable $x_F$ of $D$-meson, within the conditions of the planned SPD NICA experiment are presented for the first time.

hep-ph↗

arXiv2022

Production of three isolated photons in the parton Reggeization approach at high energies

We study a large-$p_T$ three-photon production in proton-proton collisions at the LHC. We use the leading order (LO) approximation of the parton Reggeization approach consistently merged with the next-to-leading order corrections originated from the emission of additional jet. For numerical calculations we use the parton-level generator KaTie and modified KMR-type unintegrated parton distribution functions which satisfy exact normalization conditions for arbitrary $x$. We compare our prediction with data from ATLAS collaboration at the center-of-mass energy $\sqrt{s}=8$ TeV. We find that the inclusion of the real next-to-leading-order corrections leads to a good agreement between our predictions and data with the same accuracy as for the next-to-next-to-leading calculations based on the collinear parton model of QCD. At higher energies ($\sqrt{s}=13$ and 27 TeV) parton Reggeization approach predicts larger cross sections, up to $\sim 15$ \% and $\sim 30$ \%, respectively.

hep-ph↗

arXiv2021

Estimates for the single-spin asymmetries in $p^{\uparrow}p \to J/ψX$ process at PHENIX RHIC and SPD NICA

We study the transverse single-spin asymmetry (TSSA) in $p^{\uparrow}p \to J/ψX$ reaction, incorporating both transverse-momentum and spin effects. To predict production cross section of prompt $J/ψ$ we use two different approaches, the non-relativistic QCD (NRQCD) factorization approach and the Improved Color Evaporation Model (ICEM), and show how the predicted results for TSSAs depend on choice of hadronization model. For initial-state factorization we consider two models: the standard Generalized Parton Model (GPM) and the Colour Gauge-Invariant version of it (CGI-GPM). We demonstrate that PHENIX collaboration data on TSSA in the process $p^{\uparrow}p \to J/ψX$ constrain the gluon Sivers function of the proton and rule-out one of existing parameterizations. Estimates for the TSSAs in $p^{\uparrow}p \to J/ψX$ process for the conditions of the future SPD NICA experiment are presented for the first time.

hep-ph↗

arXiv2019

Angular decorrelations in $γ+ 2 jet$ events at high energies in the parton Reggeization approach

We study associated production of prompt photon and two jets at high energies in the framework of the parton Reggeization approach, which is based on multi-Regge factorization of hard processes and Lipatov's effective theory of Reggeized gluons and quarks. In this approach, initial-state off-shell effects and transverse momenta of initial partons are included in a gauge-invariant way. We compute azimuthal angle difference spectra in $γ+ 2 jets$ events and compare results with data from D0 Collaboration at the Tevatron. It was found that agreement between predictions and data can be achieved only under assumption on strong violation in transverse momentum ordering during initial-state QCD evolution which corresponds multi-Regge kinematical regime instead of DGLAP picture.

hep-ph↗

arXiv2019

Evidence in favor of Single Parton Scattering mechanism in $Υ$ and $D$ associated production at the LHC

Associated production of prompt $Υ(1S)$ and $D^{+,0}$ mesons has been proposed as a golden channel for the search of Double Parton Scattering, because Single Parton Scattering contribution to the cross-section is believed to be negligible on a basis of leading order calculations in the Collinear Parton Model. We study this process in the leading order approximation of the Parton Reggeization Approach. Hadronization of $b\bar{b}$-pair into bottomonium states is described within framework of the NRQCD-factorization approach while production of $D$ mesons is described in the fragmentation model with scale-dependent fragmentation functions. We have found good agreement with LHCb data for various normalized differential distributions, except for the case of spectra on azimuthal angle differences at the small $Δφ$ values. Crucially, the total cross-section in our Single Parton Scattering model accounts for more than one half of observed cross-section, thus dramatically shrinking the room for Double Parton Scattering mechanism.

hep-ph↗

arXiv2018

Correlation observables in $ΥD$ pair production at the LHC within the parton Reggeization approach

We study angular correlations in associated hadroproduction of $Υ(1S)$ with the $D^{\pm}$ and $D^0$-mesons at the LHC in the Leading Order of the parton Reggeization approach. Hadronization of $b\bar{b}$-pair to $Υ(1S)$ is described within the NRQCD-factorization framework. Production of $D-$mesons is described in the fragmentation model with scale-dependent fragmentaion functions. We have found good agreement with LHCb data for various differential distributions, except for the case of spectra on azimuthal angle differences at the small $\triangleφ$ values. The total cross-section in our Single Parton Scattering model, calculated under conservative assumptions, accounts for almost one half of observed cross-section, thus dramatically shrinking the room for Double Parton Scattering mechanism.

hep-ph↗

arXiv2017

$B{\bar B}$ angular correlations at the LHC in parton Reggeization approach merged with higher-order matrix elements

We calculate the angular distribution spectra between beauty ($B$) and anti-beauty ($\bar B$) mesons in proton-proton collisions in the leading order approximation of the parton Reggeization approach consistently merged with the next-to-leading order corrections from the emission of additional hard gluon. To describe b-quark hadronization we use the universal scale-depended parton-to-meson fragmentation functions extracted from the world $e^+e^-$ annihilation data. We have obtained good agreement between our predictions and data from the CMS Collaboration at the energy $\sqrt{S}=7$ TeV for $B \bar B$ angular correlations within uncertainties and without free parameters. Predictions for analogous correlation observables at $\sqrt{S}=13$ TeV are provided.

hep-ph↗

arXiv2017

Heavy quark production at the LHC in the Parton Reggeization Approach

We present the general introduction to the Parton Reggeization Approach and discuss some new results on large-p_T production for heavy quarks at the LHC. We concentrate here on study of different correlation spectra for b\barb-jet pairs, D\barD-meson pairs and DD-meson pairs.

hep-ph↗

arXiv2016

Large-p_T production of D mesons at the LHCb in the parton Reggeization approach

The production of D mesons in proton-proton collisions at the LHCb detector is studied. We consider the single production of D^0, D^+, D^star, and D_s^+ mesons and correlation spectra in the production of DbarD and DD pairs at the sqrt{S}=7 TeV and sqrt{S}=13 TeV. In case of the single D-meson production we calculate differential cross sections over transverse momentum p_T while in the pair DbarD,DD-meson production the cross sections are calculated over the azimuthal angle difference, rapidity difference, invariant mass of the pair M and over the p_T of the one meson from a pair. The cross sections are obtained at the leading order of the parton Reggeization approach using Kimber-Martin-Ryskin unintegrated parton distribution functions in a proton. To describe the D-meson production we use universal scale-dependent c-quark and gluon fragmentation functions fitted to e^+e^- annihilation data from CERN LEP1. Our predictions find a good agreement with the LHCb Collaboration data within uncertainties and without free parameters.

hep-ph↗

arXiv2014

B-meson production in the Parton Reggeization Approach at Tevatron and the LHC

We study the inclusive hadroproduction of $B^0$, $B^+$, and $B_s^0$ mesons at leading order in the parton Reggeization approach using the universal fragmentation functions extracted from the combined $e^+e^-$ annihilation data from CERN LEP1 and SLAC SLC colliders. We have described $B$-meson transverse momentum distributions measured in the central region of rapidity by the CDF Collaboration at Fermilab Tevatron and CMS Collaboration at LHC within uncertainties and without free parameters, applying Kimber-Martin-Ryskin unintegrated gluon distribution function in a proton. The forward $B$-meson production ($2.0<y<4.5$) measured by the LHCb Collaboration also has been studied and expected disagreement between our theoretical predictions and data has been obtained.

hep-ph↗

arXiv2014

Open charm production in the parton Reggeization approach: from Tevatron to LHC

We study the inclusive hadroproduction of D^0, D^+, D^star+, and D_s^+ mesons at leading order in the parton Reggeization approach endowed with universal fragmentation functions fitted to $e^+e^-$ annihilation data from CERN LEP1. We have described $D$-meson transverse momentum distributions measured in the central region of rapidity by the CDF Collaboration at Tevatron (|y|<1) and ALICE Collaboration at LHC (|y|<0.5) within uncertainties and without free parameters, using Kimber-Martin-Ryskin unintegrated gluon distribution function in a proton. The forward D-meson production (|y|>2.0) measured by the LHCb Collaboration also has been studied and expected disagreement between our theoretical predictions and data has been obtained.

hep-ph↗