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

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.