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SUMMARY:Angular distributions of $D$-meson in the $D\\bar D-$pair producti
 on at high energy
DTSTART;VALUE=DATE-TIME:20261030T091500Z
DTEND;VALUE=DATE-TIME:20261030T093000Z
DTSTAMP;VALUE=DATE-TIME:20261030T193855Z
UID:indico-contribution-6165@cern.ch
DESCRIPTION:Speakers: Lev Alimov (Samara University)\nThe process of $D$-m
 eson production is usually considered an important probe for investigating
  gluon parton distribution functions in the proton\, as well as the heavy 
 quark hadronization mechanism in QCD. In this report\, we demonstrate that
  studying the angular distribution of the $D$-meson in the $D\\bar{D}$-pai
 r production can be used to check the applicability of different factoriza
 tion approaches\, such as the collinear parton model (CPM)[1]\, TMD-factor
 ization (TMD)[2]\, and high-energy factorization (HEF)[3]. First\, angular
  distributions are sensitive to the ratio $r=p_T/M$\, where $p_{T}$ is the
  $D\\bar{D}$-pair  transverse momentum and $M$ is its invariant mass. Sign
 ificantly different azimuthal angle spectra were found in two regions\, $r
  \\ll 1$ and $r \\gg 1$\, which correspond to the applicability regions of
  TMD and CPM\, respectively. At large $r \\gg 1$\, where TMD is inapplicab
 le\, we found different angular distributions predicted by the fixed-order
  NLO CPM and by HEF\, where all-order resummation is applied using uninteg
 rated parton distribution functions in the proton [4].\n\nReferences:\n\n[
 1] J. Collins\, Foundations of Perturbative QCD (Cambridge\nUniversity Pre
 ss\, Cambridge\, 2011).\n\n[2] J. C. Collins\, D. E. Soper\, and G. F. Ste
 rman\,  Adv. Ser. Dir. High Energy Phys.\n5\, 1 (1989).\n\n[3] J. C. Colli
 ns and R. K. Ellis\, Nucl. Phys. B360\, 3 (1991).\nS. Catani and F. Hautma
 nn\, Nucl. Phys. B427\, 475 (1994)\; L.V. Gribov\, E. M. Levin\, and M. G.
  Ryskin\, Phys. Rep. 100\, 1 (1983)\;\n\n[4] M. A. Nefedov\, V. A. Saleev\
 , and A. V. Shipilova\, Phys. Rev. D 87\, 094030 (2013)\; A. V. Karpishkov
 \, M. A. Nefedov\, and V. A. Saleev\, Phys. Rev. D 96\, 096019 (2017)\; M.
 A. Nefedov and V.A. Saleev\, Phys. Rev. D102 (2020)\, 114018\;\n\nhttps://
 indico.particle.mephi.ru/event/626/contributions/6165/
LOCATION: Conference Hall 3
URL:https://indico.particle.mephi.ru/event/626/contributions/6165/
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