761 articles – 7594 Notices  [english version]
 HAL : in2p3-00712762, version 1
 arXiv : 1206.6355
 Physical Review Letters 109 (2012) 112001
 Measurement of Exclusive $\pi^0$ Electroproduction Structure Functions and their Relationship to transverse generalized parton distributions
 CLAS Collaboration(s)
 (2012)
 Exclusive $\pi^0$ 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 $Q^2$, $x_B$, $t$, and $\phi_\pi$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$,\ $-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $\sigma_T +\epsilon \sigma_L, \sigma_{TT}$ and $\sigma_{LT}$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $\sigma_T +\epsilon \sigma_L$ and fails to account for $\sigma_{TT}$ and $\sigma_{LT}$, 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 $\pi^0$ electroproduction offers direct experimental access to the transversity GPDs.
 Thème(s) : Physique/Physique des Hautes Energies - ExpériencePhysique/Physique des Hautes Energies - PhénoménologiePhysique/Physique Nucléaire Expérimentale
 Lien vers le texte intégral : http://fr.arXiv.org/abs/1206.6355
 in2p3-00712762, version 1 http://hal.in2p3.fr/in2p3-00712762 oai:hal.in2p3.fr:in2p3-00712762 Contributeur : Emmanuelle Vernay <> Soumis le : Jeudi 28 Juin 2012, 08:40:13 Dernière modification le : Mercredi 24 Octobre 2012, 09:35:53