Quark Gluon Fusion

Introduction

Studies of the collisions of various hadrons and nuclei at different centrality and energy enable to explore the QCD phase diagram over a wide range of temperature and baryon density in search for the deconfinement and chiral phase transitions and critical point.

The existing calculations of the QCD equation of state [1,2,3,4], which are mostly performed on the lattice by the calculation of the path integrals numerically, predict a smooth crossover phase transition at small net-baryon density between hadron resonances and quark-gluon plasma phases. At high net-baryon density, it is expected that this transition is the phase transition of the first order with the same boundary of deconfined and chirally symmetric phases. Consequently,

Around percolation threshold, strong fluctuations in colors of strings appear what lead to large fluctuations in some observables, which one can find by the event by event analysis [8].

In the present study, we calculated long-range correlation coefficients in a Monte Carlo model with string fusion for proton-proton, proton-nucleus, and nucleus-nucleus collisions at the energy range from a few up to several hundred GeV per nucleon, where the critical effects are expected.

The paper is organized as follows: in the next section we very briefly describe the main features of the Monte Carlo model with string fusion. Then, we discuss the observables selected for study. After that, we present the results we give our

A model for the string fusion accounting finite rapidity width of strings for pp, pA and AA collisions is developed and applied to center-of-mass energy range from a few to hundred GeV per nucleon. Long-range correlation coefficients between transverse momenta and multiplicities are studied. Smooth monotonic behaviour of n-n and pt-n correlation with energy was found. A non-monotonic pt-pt correlations as a function of energy in forward rapidity window was obtained in Ar+Ca collisions in the forward region. In the future, more detailed scan, including calculation of correlations in narrow centrality classes, is required, as well as an extension of the model for study of other correlation and fluctuation observables, available for the