Contribution of exclusive diffractive processes to the measured azimuthal asymmetries in SIDIS

0532580 - ÚPT 2021 RIV NL eng J - Journal Article
Agarwala, J. - Alexeev, M. G. - Alexeev, G. D. - Srnka, Aleš … Total 208 authors
Contribution of exclusive diffractive processes to the measured azimuthal asymmetries in SIDIS.
Nuclear Physics. B. Roč. 956, JUL (2020), č. článku 115039. ISSN 0550-3213. E-ISSN 1873-1562
Institutional support: RVO:68081731
Keywords : deep-inelastic scattering
OECD category: Particles and field physics
Impact factor: 2.759, year: 2020
Method of publishing: Open access
https://www.sciencedirect.com/science/article/pii/S0550321320301255

Hadron leptoproduction in Semi-Inclusive measurements of Deep-Inelastic Scattering (SIDIS) on unpolarised nucleons allows one to get information on the intrinsic transverse momentum of quarks in a nucleon and on the Boer-Mulders function through the measurement of azimuthal modulations in the cross section. These modulations were recently measured by the HERMES experiment at DESY on proton and deuteron targets, and by the COMPASS experiment using the CERN SPS muon beam and a (LiD)-Li-6 target. In both cases, the amplitudes of the cos phi(h) and cos 2 phi(h) modulations show strong kinematic dependences for both positive and negative hadrons. It has been known since some time that the measured final-state hadrons in those SIDIS experiments receive a contribution from exclusive diffractive production of vector mesons, particularly important at large values of z, the fraction of the virtual photon energy carried by the hadron. In previous measurements of azimuthal asymmetries this contribution was not taken into account, because it was not known that it could distort the azimuthal modulations. Presently, a method to evaluate the contribution of the exclusive reactions to the azimuthal asymmetries measured by COMPASS has been developed. The subtraction of this contribution results in a better understanding of the kinematic effects, and the remaining non-zero cos 2 phi(h) modulation gives indication for a non-zero Boer-Mulders effect.
Permanent Link: http://hdl.handle.net/11104/0311023