9-14 September 2018
University of Ferrara
Europe/Rome timezone

COMPASS results on measurement of the spin-dependent structure function g_2 of the proton. (on behalf of the COMPASS Collaboration)

Not scheduled
University of Ferrara

University of Ferrara

Polo degli Adelardi Via Adelardi 33 Ferrara Italy
Parallel Sessions Nucleon Helicity Structure


Andrea Bressan (TS)


The spin-dependent structure function g_2 of the proton has been exacted by the COMPASS experiment (SPS, CERN) from DIS data collected in 2010 using 160 GeV/c muon beam and transversely polarized NH_3 target. Within the so-called Wandzura-Wilczek approximation, g2 can be related to the spin-dependent structure function g_1 while from the constraints imposed by Lorentz invariance relations, it is expected to be linked to the first k_T-moment of the g_{1T} TMD PDF. The extraction of g_2 virtual photon-absorption asymmetry A_2 was based on the measurement of A_{T}^{cos(\phi_S)} asymmetry and on the available global fit results on g_1 and ratio of longitudinal and transverse photoabsorption cross sections R. Compared to the previous measurements performed by SLAC and HERMES experiments, COMPASS covers larger kinematic range (0.003 < x < 0.9), providing access to the previously unexplored low-x domain. In this talk COMPASS preliminary results on g_2 will be presented along with relevant details of the analysis and comparison with previous measurements.

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