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Longitudinal virtual photons and the interference terms in ep collisions

Urszula Jezuita-Dabrowska·Maria Krawczyk
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Abstract

The importance of the contributions of the longitudinally polarized virtual photon in ep collisions is investigated. We derive the factorization formulae for the unpolarized inclusive and semi-inclusive ep collisions in an arbitrary reference frame. The numerical calculations for the prompt photons production in the unpolarized Compton process (e p --> e gamma X) at the ep HERA collider are performed in the Born approximation. We studied various distributions in the ep centre-of-mass frame and found that the differential cross section for the longitudinally polarized intermediate photon and the term due to the interference between the longitudinal- and transverse- polarization states of the photon are small, i.e. below 10% of the cross section. Moreover, these two contributions almost cancel one another, leading to a stronger domination of the transversely polarized virtual photon, even for its large virtuality. Relevance of the resolved longitudinal photon in a jet production in DIS events at HERA is commented. A relatively large (about 30%) effect due to the longitudinal-transverse interference term was found in the azimuthal-angle distribution in the Breit frame.

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Urszula Jezuita-Dabrowska, Maria Krawczyk. 2002-11-08. Longitudinal virtual photons and the interference terms in ep collisions. https://arxiv.org/abs/hep-ph/0211112

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