In-Medium rho^0 Spectral Function Study via the 2H, 3He, 12C(gamma,pi+pi-) Reaction
Abstract
We report a helicity analysis of sub-threshold rho^0 production on 2H, 3He and 12C at low photo-production energies. The results are indicative of a large longitudinal rho^0 polarization (l=1, m=0) and are consistent with a strong helicity-flip production mechanism. This signature is used to extract in-medium rho^0_L invariant mass distributions for all three nuclei in a manner which is less model-dependent than previous measurements. The results are compared to kinematic and phenomenological models of the rho^0 spectral function. The 2H and 3He data distributions support the role of N*(1520) excitation in shaping the in-medium rho^0_L invariant mass distribution, while the 12C distributions are consistent with quasi-free rho^0_L production. The data support an in-medium modification of the rho^0_L invariant mass distribution.
Keywords
Cite
@article{arxiv.nucl-ex/0310011,
title = {In-Medium rho^0 Spectral Function Study via the 2H, 3He, 12C(gamma,pi+pi-) Reaction},
author = {G. M. Huber and G. J. Lolos and Z. Papandreou and A. Shinozaki and E. J. Brash and M. Iurescu and G. Garino and K. Maruyama and K. Maeda and T. Suda and A. Toyofuku and B. K. Jennings and A. Sasaki and H. Yamashita},
journal= {arXiv preprint arXiv:nucl-ex/0310011},
year = {2009}
}
Comments
29 pages, 23 figures