Results on longitudinal spin physics at COMPASS

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• 作者：Malte Wilfert¹ ; ² ; ^{mwilfert@cern.ch" class="auth_mail" title="E-mail the corresponding author} ; on behalf of the COMPASS Collaboration
• 关键词：COMPASS ; deep inelastic scattering ; spin ; A1 ; g1 ; structure function ; polarised parton distribution functions ; QCD analysis ; Bjorken sum rule ; ALL ; ΔG
• 刊名：Nuclear and Particle Physics Proceedings
• 出版年：2016
• 出版时间：January-March 2016
• 年：2016
• 卷：270-272
• 期：Complete
• 页码：41-45
• 全文大小：432 K

文摘

The COMPASS experiment at the CERN SPS has taken data for deep inelastic scattering of polarised muons off a polarised NH₃ target in 2007 and 2011 and off a polarised ⁶LiD target in 2002–2004 and 2006.

We present our new results on the longitudinal double spin asymmetry $A_1^{\mathrm{p}}$ and the spin-dependent structure function $g_1^{\mathrm{p}}$ obtained from the 2011 data set. These results are used in a NLO QCD fit to the world data to obtain the polarised parton distributions. Also an update on our results on the Bjorken sum rule, connecting the integral of the non-singlet spin-dependent structure function with the ratio of the weak coupling constants, is given.

The gluon polarisation can be accessed directly via the photon gluon fusion process in semi-inclusive deep inelastic scattering. This process is studied using the p_T$p_T$ dependence of charged hadron asymmetries. The latest results indicate a positive gluon polarisation in the kinematic region of COMPASS.