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

Experimental studies of GPDs at COMPASS

10 Sep 2018, 15:05
A5 (Polo degli Adelardi - Via Adelardi, 33)


Polo degli Adelardi - Via Adelardi, 33

Parallel Sessions 3D Structure of the Nucleon: GPDs and Form Factors 3D Structure of the Nucleon: GPDs and Form Factors


Mr Andrea Ferrero (CEA-Saclay/IRFU/DPhN)


Together, GPDs and TMDs provide the most complete description of the partonic structure of the nucleon, and their study represents the major goal of the COMPASS-II program. GPDs are experimentally accessible via lepton-induced exclusive reactions, in particular DVCS and DVMP. At COMPASS, these processes are investigated using a 160 GeV high intensity muon beam impinging on a 2.5~m long liquid hydrogen target. In order to optimize the selection of exclusive reactions at these energies, the target is surrounded by a new barrel-shaped time-of-flight system to detect the recoiling particles. The pure DVCS cross-section and its $|t|$-dependence are extracted from the sum of cross-sections measured with opposite beam charges and polarizations. From this measurement, the first estimate of the transverse size of the nucleon in the uncharted $x_{Bj}$ domain from 0.02 to 0.20 will be given. COMPASS is also capable of accessing several DVMP channels, from which different combinations of quark and gluon GPDs can be extracted. In this talk we will report on the first measurement of the exclusive $\pi^0$ cross section and its $|t|$-dependence in the same $x_{Bj}$ domain from 0.02 to 0.20.

Primary author

Mr Andrea Ferrero (CEA-Saclay/IRFU/DPhN)

Presentation Materials