We report the first extraction of the pion-nucleon multipole s near the production threshold for the nπ+ channel at relatively high momentum transfer (Q2 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 G1 within the light-cone sum rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754 GeV electron beam on a prot on target. The differential cross section and the π−N-multipole E0+/GD 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 Q2 independent.
Measurement of the generalized form factors near threshold via gamma* p -> n pi(+) at high Q(2)
CONTALBRIGO, Marco;PAPPALARDO, Luciano Libero;
2012
Abstract
We report the first extraction of the pion-nucleon multipole s near the production threshold for the nπ+ channel at relatively high momentum transfer (Q2 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 G1 within the light-cone sum rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754 GeV electron beam on a prot on target. The differential cross section and the π−N-multipole E0+/GD 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 Q2 independent.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
