Long-range rapidity correlations in high energy AA collisions in Monte Carlo model with string fusion

The magnitude of long-range correlations between observables in two separated rapidity windows, proposed as a signature of the string fusion and percolation phenomenon, is studied in the framework of non-Glauber Monte Carlo string-parton model, based on the picture of elementary collisions of color dipoles. The predictions, obtained with and without string fusion, demonstrate effects of color string fusion on the observables in Pb-Pb collisions at the LHC: decrease of n-n correlation coefficient with centrality and negative pt-n correlations, if the sufficiently effective centrality estimator is applied. In general case it is shown that the values of n-n and pt-n correlation coefficients strongly depend on the method of collision centrality fixation. In contrast, the predictions obtained for pt-pt correlation have almost no effect of centrality determination method and the corresponding experimental data would produce the strong limitation on the transverse radius of a string.Comment: 5 pages, 4 figures, to be published in EPJ Web of Conferences (INPC2013 proceedings

Forward-backward multiplicity correlations in pp collisions at high energy in Monte Carlo model with string fusion

The correlations between multiplicities in two separated rapidity windows, is studied in the framework of the Monte Carlo model based on the picture of string formation in elementary collisions of colour dipoles. The hardness of the elementary collisions is defined by a transverse size of the interacting dipoles. The dependencies of the forward-backward correlation strength on the width and position of the pseudorapidity windows, as well as on transverse momentum range of observed particles were studied. It is demonstrated that taking into account of the string fusion effects improves the agreement with the available experimental data.Comment: 4 pages, 3 figures, proc. PANIC 201