New Measurement of Parity Violation in Elastic Electron-Proton Scattering and Implications for Strange Form Factors

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The result is A = -15.05 +- 0.98(stat) +- 0.56(syst) ppm at the kinematic point theta_lab = 12.3 degrees and Q^2 = 0.477 (GeV/c)^2. The measurement implies that the value for the strange form factor (G_E^s + 0.392 G_M^s) = 0.025 +- 0.020 +- 0.014, where the first error is experimental and the second arises from the uncertainties in electromagnetic form factors. This measurement is the first fixed-target parity violation experiment that used either a `strained' GaAs photocathode to produce highly polarized electrons or a Compton polarimeter to continuously monitor the electron beam polarization.Comment: 8 pages, 4 figures, Tex, elsart.cls; revised version as accepted for Phys. Lett.

Display of probability densities for data from a continuous distribution

Based on cumulative distribution functions, Fourier series expansion and Kolmogorov tests, we present a simple method to display probability densities for data drawn from a continuous distribution. It is often more efficient than using histograms.Comment: 5 pages, 4 figures, presented at Computer Simulation Studies XXIV, Athens, GA, 201

Measurement of the Generalized Polarizabilities of the Proton in Virtual Scattering at Q2=0.92 and 1.76 GeV2: I. Low Energy Expansion Analysis

Virtual Compton Scattering is studied at the Thomas Jefferson National Accelerator Facility at low Center-of-Mass energies, below pion threshold. Following the Low Energy Theorem for the $ep \to ep \gamma$ process, we obtain values for the two structure functions Pll-Ptt/epsilon and Plt at four-momentum transfer squared Q2=0.92 and 1.76 GeV2.Comment: 4 pages, 2 figures, to be submitted to PRL. Figs 1 and 2, lettering enlarge

Measurement of the induced proton polarization P-n in the C-12(e,e `(p)over-right-arrow) reaction

The first measurements of the induced proton polarization P-n for the C-12(e,e’(p) over right arrow) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (w, q) approximate to (294 MeV, 756 MeV/c) and sampled a missing momentum range of 0-250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. The distorted-wave impulse approximation provides good agreement with data fur the 1p(3/2) shelf. The data for the continuum suggest that both the 1s(1/2) shell and underlying l > 1 configurations contribute

Measurement of recoil proton polarizations in the electrodisintegration of deuterium by polarized electrons

In order to test modem theories of two-nucleon bound and scattering states, we have measured the spin polarization of ejectile protons in the electrodisintegration reaction d((e) over right arrow, e’(p) over right arrow)n. Compared with spin-averaged observations, these observables offer the potential of enhanced sensitivity to details of the reaction process. The experiment was carried out in quasielastic kinematics (q(mu)q(mu)= -2m(p) omega= -0.38GeV(2)/c(2)). Protons were detected at two angles corresponding to neutron recoil momenta p(r) of 0 and 100MeV/c. Full nonrelativistic calculations of the polarization transfer components s(l) and s(t), including leading order relativistic contributions, describe our measurements well, but calculations of the induced polarization s(n) at p(r) = 100 MeV/c underpredict the experimental result. (C) 1999 Published by Elsevier Science B.V. All rights reserved