STAR results on high transverse momentum, heavy flavour and electromagnetic probes

Abstract

We summarize here recent results from the STAR collaboration focusing on processes involving large momentum transfers. Measurements of angular correlations of di-hadrons are explored in both the pseudorapidity (η) and azimuthal (ϕ) projections. In central Au+Au, an elongated structure is found in the η projection which persists up to the highest measured p⊥. After quantifying the particle yield in this structure and subtracting it from the near-side yield, we observe that the remainder exhibits a behaviour strikingly similar to that of the near-side yield in d+Au. For heavy flavour production, using electron–hadron correlations in p + p collisions, we obtain an estimate of the b-quark contribution to the non-photonic electrons in the p⊥ region 3–6 GeV/c, and find it consistent with FONLL calculations. Together with the observed suppression of non-photonic electrons in Au+Au, this strongly suggests suppression of b-quark production in Au+Au collisions. We discuss results on the mid-rapidity ϒ cross-section in p + p collisions. Finally, we present a proof-of-principle measurement of photon–hadron (γ–h) correlations in p + p collisions, paving the way for the tomographic study of the matter produced in central Au+Au via γ-jet measurements.