CERN Accelerating science

Published Articles
Title	The new spin physics program of the COMPASS experiment
Author(s)	Silva, Luís (LIP, Lisbon)
Collaboration	COMPASS Collaboration
Publication	2015
Number of pages	9
In:	EPJ Web Conf. 95 (2015) 04063
In:	3rd International Conference on New Frontiers in Physics, Kolymbari, Crete, Greece, 28 Jul - 06 Aug 2014, pp.04063
DOI	10.1051/epjconf/20159504063
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN SPS ; COMPASS NA58
Abstract	The COMPASS experiment, at CERN SPS, has been compiling for more than a decade successful and precise results on nucleon structure and hadron spectroscopy, leading to statistical errors much smaller than previously measured. The new COMPASS spin physics program, starting this year, aims to a rather complete nucleon structure description; this new representation goes beyond the collinear approximation by including the quark intrinsic transverse momentum distributions. The theoretical framework, for this new picture of the nucleon, is given by the Transverse Momentum Dependent distributions (TMDs) and by the Generalised Parton Distributions (GPDs). The TMDs, in particular Sivers, Boer-Mulders, pretzelosity and transversity functions will be obtained through the polarised Drell-Yan process, for the first time. The results will be complementary to those already obtained via polarised Semi-Inclusive Deep Inelastic Scattering (SIDIS). Also unpolarised SIDIS will be studied, allowing the knowledge improvement of the strange quark PDF and the access to the kaon fragmentation functions (FFs). Deeply Virtual Compton Scattering (DVCS) off an unpolarised hydrogen target will be used to study the GPDs, in a kinematic region not yet covered by any existing experiment.
Copyright/License	CC-BY-4.0

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