S.D. Holmes

Electroproduction of single pions at low E and a measurement of the pion form factor up to Q = 10 G~V~

We report measurements of the electroproduction of single charged pions from hydrogen and deuterium targets for values of epsilon in the range 0.35 < epsilon < 0.45. Data were taken with a hydrogen target at the (W,Q/sup 2/) points (2.15 GeV, 1.2 GeV/sup 2/), (2.65, 2.0), (2.65, 3.4), (2.65, 6.0), and (2.65, 10.0). Data were taken with a deuterium target at the (W, Q/sup 2/) points (2.15, 1.2) and (2.65, 2.0). The transverse cross section obtained by using these data in conjunction with earlier data at high epsilon to separate the longitudinal and transverse components is used in conjunction with the new data and the t-channel Born term to determine the pion form factor and to re-evaluate previously reported measurements. In the range 0.15 GeV/sup 2/ < Q/sup 2/ < 10.0 GeV/sup 2/ the pion form factor can be described by the simple pole form (1 + Q/sup 2//(0.462 +- 0.024))/sup -/1.

Electroproduction of single pions at low epsilon and a measurement of the pion form factor up to Q/sup 2/ = 10 GeV/sup 2/

We report measurements of the electroproduction of single charged pions from hydrogen and deuterium targets for values of epsilon in the range 0.35 < epsilon < 0.45. Data were taken with a hydrogen target at the (W,Q/sup 2/) points (2.15 GeV, 1.2 GeV/sup 2/), (2.65, 2.0), (2.65, 3.4), (2.65, 6.0), and (2.65, 10.0). Data were taken with a deuterium target at the (W, Q/sup 2/) points (2.15, 1.2) and (2.65, 2.0). The transverse cross section obtained by using these data in conjunction with earlier data at high epsilon to separate the longitudinal and transverse components is used in conjunction with the new data and the t-channel Born term to determine the pion form factor and to re-evaluate previously reported measurements. In the range 0.15 GeV/sup 2/ < Q/sup 2/ < 10.0 GeV/sup 2/ the pion form factor can be described by the simple pole form (1 + Q/sup 2//(0.462 +- 0.024))/sup -/1.

Hadronic Final States in Electroproduction

We present data on electroproduction off protons in which a hadron moving in approximately the same direction as the virtual photon is detected. Measurements were made at data points with nominal (Q2,W) values of (0.6,2.68), (1.2,2.68), (2.0,2.68) and (1.2,2.15) in (GeV2,GeV). The virtual photoproduction cross sections for (π±, K+, p) + Missing Mass are studied as a function of missing mass, Feynman scaling variables, Q2 and W. The results suggest a simple scaling behavior for pions. The data for the channel π+ n are used to determine values for the pion form factor. Protons show a simple behavior as a function of Q2 but not W. The K+ data show that the K+Σo cross section falls more rapidly than the K+Λ cross section as Q2 increases. There is evidence for hyperon resonance production in the missing mass distributions.