Determination of the pion charge form factor at Q2=1.60 and 2.45 (GeV/c)2

Phys Rev Lett. 2006 Nov 10;97(19):192001. doi: 10.1103/PhysRevLett.97.192001. Epub 2006 Nov 6.


The 1H(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 chromodynamics prediction.