Measurements of Differential Transverse Momentum Correlation Function from the STAR Experiment

The event anisotropy measurements at RHIC have revealed that the matter created in heavy ion collisions flows with very little viscosity. The estimation of ``viscosity-to-entropy'' ratio is currently a subject of extensive study [1]. In order to find quantitative experimental information on the viscosity of the medium we present measurements of differential transverse momentum correlation function from the STAR experiment in $Au + Au$ collisions at $\sqrt{s_{NN}} = $ 200 GeV. We study the correlation function of the particles as a function of pseudo-rapidity and azimuthal angle in the range $0.2