Measurement of the generalized form factors near threshold via gamma* p -> n pi(+) at high Q(2)статья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:We report the first extraction of the pion-nucleon multipoles near the production threshold for the n pi(+) channel at relatively high momentum transfer (Q(2) up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G(1) within the light-cone sum-rule (LCSR) framework as well as the axial form factor G(A). The data analyzed in this work were collected by the nearly 4 pi CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the pi-N multipole E0+/G(D) were measured using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q(2) independent.