Using coherent dipion photoproduction to image gold nuclei

Abstract

Vector meson photoproduction offers the opportunity to image target nuclei. The two-dimensional Fourier transform d\sigma_{coherent}/dtdσcoherent/dt of coherent vector meson photoproduction gives the two-dimensional distribution of interaction sites in the target. Since vector meson photoproduction occurs, at lowest order, via two-gluon exchange, this is sensitive to gluon shadowing. We present an analysis of \pi^+\pi^-π+π− photoproduction using data from the STAR detector and a study of d\sigma_{coherent}/dtdσcoherent/dt, with an emphasis on probing the nuclear shape and its systematic uncertainties.