Physical Review C
We report the measurement of near-threshold neutral pion electroproduction cross sections and the extraction of the associated structure functions on the proton in the kinematic range Q(2) from 2 to 4.5 GeV2 and W from 1.08 to 1.16 GeV. These measurements allow us to access the dominant pion-nucleon s-wave multipoles E0+ and S0+ in the near-threshold region. In the light-cone sum-rule framework (LCSR), these multipoles are related to the generalized form factors G(1)(pi 0p) (Q(2)) and G(2)(pi 0p) (Q(2)). The data are compared to these generalized form factors and the results for G(1)(pi 0p) (Q(2)) are found to be in good agreement with the LCSR predictions, but the level of agreement with G(2)(pi 0p) (Q(2)) is poor. DOI: 10.1103/PhysRevC.87.045205
Khetarpal, P., Stoler, P., Aznauryan, I. G., Kubarovsky, V., Adhikari, K. P., Adikaram, D., ... & Anghinolfi, M. (2013). Near-threshold neutral pion electroproduction at high momentum transfers and generalized form factors. Physical Review C, 87(4), 045205.