Comparing correlation predictions from a glasma flux-tube model with measurements

A Glasma flux-tube model has been proposed to explain strong elongation on relative pseudorapidity ($\eta$) of the same-side 2D peak in minimum-bias angular correlations from $\sqrt{s_{NN}}$ = 200 GeV Au-Au collisions. In this model the same-side peak, or ``soft ridge,'' is said to arise from coupling of the flux tubes to radial flow. Gluons radiated transversely from the flux tubes are boosted by radial flow to form a narrow structure or ridge on azimuth. We have tested this conjecture by comparing predictions for particle production, spectra and transverse momentum correlations [1] from the Glasma model and conventional fragmentation processes with measurements. We conclude that the Glasma model is not relevant for understanding the same-side $\eta$-elongated correlations in Au-Au collisions at RHIC. A two-component model (soft plus hard) of hadron production, including minimum-bias parton fragmentation, provides a quantitative description of most data although the $\eta$ elongation remains unexplained. \\[4pt] [1] T. Lappi, arXiv:1011.0821 [hep-ph] (2010).