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Roman Pasechnik

Senior lecturer

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Spin rotation effects in diffractive electroproduction of heavy quarkonia

Author

  • Michal Krelina
  • Jan Nemchik
  • Roman Pasechnik
  • Jan Čepila

Summary, in English


In this work we present for the first time the comprehensive study of the Melosh spin rotation effects in diffractive electroproduction of S-wave heavy quarkonia off a nucleon target. Such a study has been performed within the color dipole approach using, as an example and a reference point, two popular parametrizations of the dipole cross section and two potentials describing the interaction between Q and Q¯ and entering in the Schrödinger equation based formalism for determination of the quarkonia wave functions. We find a strong onset of spin rotation effects in 1S charmonium photoproduction which is obviously neglected in present calculations of corresponding cross sections. For photoproduction of radially excited ψ

(2 S) these effects are even stronger leading to an increase of the photoproduction cross section by a factor of 2 ÷ 3 depending on the photon energy. Even in production of radially excited Υ

(2 S) and Υ
′ ′
(3 S) they can not be neglected and cause the 20–30% enhancement of the photoproduction cross section. Finally, we predict that the spin effects vanish gradually with photon virtuality Q
2
following universality properties in production of different heavy quarkonia as a function of Q2+MV2.

Department/s

  • Theoretical Particle Physics

Publishing year

2019-02-20

Language

English

Publication/Series

European Physical Journal C

Volume

79

Issue

2

Document type

Journal article

Publisher

Springer

Topic

  • Subatomic Physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 1434-6044