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arXiv · 1305.4694

Glauber gluons in pion-induced Drell-Yan processes

Chun-peng Chang·Hsiang-nan Li
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Abstract

We point out that the existence of Glauber gluons in the $k_T$ factorization theorem can account for the violation of the Lam-Tung relation, namely, the anomalous lepton angular distribution, observed in pion-induced Drell-Yan processes. Radiations, that balance the lepton-pair transverse momentum, cause the responsible spin-transverse-momentum correlation in the Glauber-gluon background. It is argued that the Glauber effect is significant in the pion due to its unique role of being a Nambu-Goldstone boson and a $q\bar q$ bound state simultaneously. This mechanism is compared to other resolutions in the literature by means of vacuum effects and Boer-Mulders functions. We propose to discriminate the above resolutions by measuring the $p\bar p$ Drell-Yan process at GSI and J-PARC.

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BibTeXRIS

Chun-peng Chang, Hsiang-nan Li. 2013-06-19. Glauber gluons in pion-induced Drell-Yan processes. https://doi.org/10.1016/j.physletb.2013.08.016

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