On the asymmetry in electroproduction of pions in double longitudinally polarized process

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• 作者：Wenjuan Mao^a ; ^b ; Xiaoyu Wang^a ; Xiaozhen Du^b ; Zhun Lu^a ; ^{zhunlu@seu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Bo-Qiang Ma^b ; ^c ; ^d ; ^{mabq@pku.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Semi-inclusive deep inelastic scattering ; Transverse momentum dependent distributions ; Spin asymmetry ; Spectator diquark model
• 刊名：Nuclear Physics A
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：945
• 期：Complete
• 页码：153-167
• 全文大小：716 K

文摘

We study the cos⁡ϕ_h$\cos {\varphi }_h$ azimuthal asymmetry in double polarized semi-inclusive pion production by considering the twist-3 effects directly from a quark–quark correlator. In particular, we evaluate the role of the transverse momentum dependent distributions $e_L(x,{\mathit{k}}_T^2)$ and $g_L^{\perp }(x,{\mathit{k}}_T^2)$ on the asymmetry. Using two different sets of spectator model results for these distributions, we predict the cos⁡ϕ_h$\cos {\varphi }_h$ asymmetry of π⁺${\pi }^{+}$, π⁻${\pi }^{-}$, and π⁰${\pi }^0$ at the kinematic configuration available at CLAS, HERMES. Our estimate shows that the asymmetries for charged and neutral pions are sizable and could be accessed by CLAS and HERMES. We also calculate the asymmetries for charged hadrons at the kinematics of COMPASS and compare them with the experimental data. We find that the asymmetry at COMPASS in our model is small which is consistent with the COMPASS data. We also find that $g_L^{\perp }$ gives the dominant contribution to the cos⁡ϕ_h$\cos {\varphi }_h$ asymmetry, while the contribution of e_L$e_L$ is almost negligible.