Non-monotonicity of $p_T$ correlations from meson-baryon mixing

Abstract

The STAR experiment has recently reported data on the $\sqrt{⟨\hat{I}”p_{T,i}\hat{I}”p_{T,j}⟩}/⟨⟨p_T⟩⟩$ charged hadron correlation in Au+Au reactions from $\sqrt{s_{NN}}=3-200$ GeV. The beam energy dependence of this quantity is non-monotonic, showing a pronounced minimum at $\sqrt{s_{NN}}\approx 7.7$ GeV, while being essentially flat at lower and higher energies. It has been proposed that such a non-monotonicity would be consistent with increased momentum correlations due to a critical point of QCD. In the present work it is shown, using a simplified model, that the observed structure can be consistently explained by the transition from a baryon dominated system to a meson dominated system and is therefore not a good observable for the critical point of QCD.

8 pages, 4 figures,