The Ratio Sigma0/Lambda at RHIC

Abstract

While yields of Sigma0 have been measured in many different colliding systems, no measurements exist in high energy nuclear collisions. It also remains unexplored whether the relative yields of Sigma0 and Lambda change in collisions of heavy ions where a dense medium may permit alternate production mechanisms, such as quark coalescence. The STAR detector at RHIC is able to reconstruct the electromagnetic Sigma0 decay into Lambda plus gamma via the weak decay of the Lambda and gamma conversions into e+e- pairs in the detector material. We report here on our measurement of the ratio Sigma0/Lambda in minimum bias 200 GeV d+Au collisions. We also compare the measured ratio to expectations from various models.