Aron M. Bernstein

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A review of photo-pion experiments on the nucleon in the near threshold region is presented. Comparisons of the results are made with the predictions of the low energy theorems of QCD calculated using chiral perturbation theory (ChPT) which is based on the spontaneous breaking of chiral symmetry as well as its explicit breaking due to the finite quark(More)
It is demonstrated that there is a dynamic isospin breaking effect in the near threshold γ * N → πN reaction due to the mass difference of the up and down quarks, which also causes isospin breaking in the πN system. The photopion reaction is affected through final state πN interactions (formally implemented by unitarity and time reversal invariance). It is(More)
Introduction This document presents a summary of the scientific motivations for the 12 GeV Upgrade of the CEBAF facility at Jefferson Lab. It is based on the document originally prepared for the April 2005 DOE Science Review of the project, and incorporates relatively minor edits and updates. We will revise it more throughly following the discussions(More)
We report in this thesis the simultaneous measurement of the logitudinal-transverse response functions, fLT and fLT', and the transverse-transverse response function fTT of the deuteron. The quasi-elastic 2 H(',e'p)n experiment reported here was conducted at the MIT/Bates Linear Accelerator Center in February, 1997. The experiment was carried out with a 40%(More)
Contributions of D waves to physical observables for neutral pion photoproduction from the proton in the near-threshold region are studied and means to isolate them are proposed. Various approaches to describe the multipoles are employed—a phenomenological one, a unitary one, and heavy baryon chiral perturbation theory. The results of these approaches are(More)
In this article we address the physical basis of the deviation of hadron shapes from spherical symmetry (non-spherical amplitudes) with focus on the nucleon and ∆. An overview of both the experimental methods and results and the current theoretical understanding of the issue is presented. At the present time the most quantitative method is the γ * p → ∆(More)
The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q2 = 0.057 GeV2/c2 are in agreement with O(p3) heavy baryon chiral(More)
College students rated protagonists of vignettes involved in extra-marital affairs in two separate studies. In the first study, where the affair resulted in the errant spouse falling in love, both the husband and wife were perceived more favorably when they cheated than when they were being cheated. The results of the second study, where the affair did not(More)
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