Measurement of Exclusive $π^0$ Electroproduction Structure Functions and their Relationship to Transversity GPDsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация: Exclusive π0 electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q2, xB, t, and ϕπ, in the Q2 range from 1.0 to 4.6 GeV2,\ −t up to 2 GeV2, and xB from 0.1 to 0.58. Structure functions σT+ϵσL,σTT and σLT were extracted as functions of t for each of 17 combinations of Q2 and xB. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates σT+ϵσL and fails to account for σTT and σLT, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive π0 electroproduction offers direct experimental access to the transversity GPDs.