Speaker
Description
Coherent photoproduction of vector mesons is sensitive to the shape of the target nucleus, as probed at Q^2 ~ (M_V/2)^2. Previously STAR presented a high-statistics measurement of d\sigma/dt for rho^0 photoproduction in ultra-peripheral Au+Au collisions, and made a two-dimensional Fourier-Bessel (Hanckel) transformation to give the distribution of targets in the nucleus. Here, we study the Q^2 evolution of d\sigma/dt and the target distribution by dividing the rho^0 signal into three different mass bins, to see how d\sigma/dt evolves with Q^2, and see the effect on the target distribution. With increasing Q^2, we expect to see a decrease in multiple interactions, which should emphasize the interior of the nucleus cmpared to measurements at lower Q^2.
