Differential Cross Section and Photon-Beam Asymmetry for the {gamma}(vector sign)n{yields}K{sup +}{sigma}{sup -} Reaction at E{sub {gamma}}=1.5-2.4 GeV
/ Authors
H. Kohri, D. S. Ahn, J. Ahn, H. Akimune, Y. Asano, We-Fu Chang, S. Daté, H. Ejiri, S. Fukui, H. Fujimura
and 47 more authors
M. Fujiwara, S. Hasegawa, K. Hicks, T. Hotta, K. Imai, T. Ishikawa, T. Iwata, H. Kawai, Z. Kim, K. Kino, N. Kumagai, S. Makino, T. Mart, T. Matsuda, T. Matsumura, N. Matsuoka, T. Mibe, M. Miyabe, Y. Miyachi, M. Morita, N. Muramatsu, T. Nakano, M. Niiyama, M. Nomachi, Y. Ohashi, H. Ohkuma, T. Ooba, D. Oshuev, C. Rangacharyulu, A. Sakaguchi, T. Sasaki, P. Shagin, Y. Shiino, A. Shimizu, H. Shimizu, Y. Sugaya, M. Sumihama, Y. Toi, H. Toyokawa, A. Wakai, Chun-Chieh Wang, Song Wang, K. Yonehara, T. Yorita, M. Yoshimura, M. Yosoi, R. Zegers
/ Abstract
Differential cross sections and photon-beam asymmetries have been measured for the {gamma}(vector sign)n{yields}K{sup +}{sigma}{sup -} and {gamma}(vector sign)p{yields}K{sup +}{sigma}{sup 0} reactions separately using liquid deuterium and hydrogen targets with incident linearly polarized photon beams of E{sub {gamma}}=1.5-2.4 GeV at 0.6<cos{theta}{sub cm}{sup K}<1. The cross section ratio of {sigma}{sub K{sup +}}{sub {sigma}{sup -}}/{sigma}{sub K{sup +}}{sub {sigma}{sup 0}}, expected to be 2 on the basis of the isospin 1/2 exchange, is found to be close to 1. For the K{sup +}{sigma}{sup -} reaction, large positive asymmetries are observed, indicating the dominance of K* exchange. The large difference between the asymmetries for the K{sup +}{sigma}{sup -} and K{sup +}{sigma}{sup 0} reactions cannot be explained by simple theoretical considerations based on Regge model calculations.
Journal: Physical Review Letters