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Transverse-spin-dependent azimuthal asymmetries of pion and kaon pairs produced in muon-proton and muon-deuteron semi-inclusive deep inelastic scattering

Publication at Faculty of Mathematics and Physics, Central Library of Charles University |
2023

Abstract

A set of measurements of azimuthal asymmetries in the production of pairs of identified hadrons in deep-inelastic scattering of muons on transversely polarised 6LiD (deuteron) and NH3 (proton) targets is presented. All available data collected in the years 2003-2004 and 2007/2010 with the COMPASS spectrometer using a muon beam of 160GeV/c at the CERN SPS were analysed.

The asymmetries provide access to the transversity distribution functions via a fragmentation function that in principle may be independently obtained from e+e- annihilation data. Results are presented, discussed and compared to existing measurements as well as to model predictions.

Asymmetries of π+π- pairs measured with the proton target as a function of the Bjorken scaling variable are sizeable in the range x>0.032, indicating non-vanishing transversity distribution and di-hadron interference fragmentation functions. As already pointed out by several authors, the small asymmetries of π+π- measured on the 6LiD target can be interpreted as indication for a cancellation of u and d-quark transversity distributions.