Determination of the Charged Pion Form Factor at Q2=1.60 and 2.45 (GeV/c)2

Fpi2 collaboration; Horn, T.; Aniol, K.; Arrington, J.; Barrett, B.; Beise, E. J.; Blok, H. P.; Boeglin, W.; Brash, E. J.; Breuer, H.; Chang, C. C.; Christy, M. E.; Ent, R.; Gaskell, D.; Gibson, E.; Holt, R. J.; Huber, G. M.; Jin, S.; Jones, M. K.; Keppel, C. E.; Kim, W.; King, P. M.; Kovaltchouk, V.; Liu, J.; Lolos, G. J.; Mack, D. J.; Margaziotis, D. J.; Markowitz, P.; Matsumura, A.; Meekins, D.; Miyoshi, T.; Mkrtchyan, H.; Niculescu, I.; Okayasu, Y.; Pentchev, L.; Perdrisat, C.; Potterveld, D.; Punjabi, V.; Reimer, P.; Reinhold, J.; Roche, J.; Roos, P. G.; Sarty, A.; Smith, G. R.; Tadevosyan, V.; Tang, L. G.; Tvaskis, V.; Vidakovic, S.; Volmer, J.; Vulcan, W.; Warren, G.; Wood, S. A.; Xu, C.; Zheng, X.

Determination of the Charged Pion Form Factor at Q2=1.60 and 2.45 (GeV/c)2

Authors

Description

The H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F_pi) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F_pi is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative Quantum Chromo-Dynamics prediction.
4 pages, 3 figures, submitted to Physical Review Letters