Spin rotation effects in diffractive electroproduction of heavy quarkonia

0503168 - ÚJF 2020 RIV US eng J - Journal Article
Křelina, M. - Nemchik, J. - Pasechnik, Roman - Čepila, J.
Spin rotation effects in diffractive electroproduction of heavy quarkonia.
European Physical Journal C. Roč. 79, č. 2 (2019), č. článku 154. ISSN 1434-6044. E-ISSN 1434-6052
R&D Projects: GA MŠMT EF16_013/0001569; GA MŠMT(CZ) LTT17018; GA MŠMT LTT18002
Institutional support: RVO:61389005
Keywords : nucleon * diffractive electroproduction * quarkonia
OECD category: Particles and field physics
Impact factor: 4.389, year: 2019
Method of publishing: Open access
https://doi.org/10.1140/epjc/s10052-019-6666-y

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 Schrodinger 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 (2S) these effects are even stronger leading to an increase of the photoproduction cross section by a factor of 2 divided by 3 depending on the photon energy. Even in production of radially excited ?(2S) and ?(3S) 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 Q2 following universality properties in production of different heavy quarkonia as a function of Q2+MV2.
Permanent Link: http://hdl.handle.net/11104/0294982