Evidence on the absence of critical transition in AMPT for Pb-Pb   collisions at $sqrt{s_{\rm{NN}}}$ = 2.76 TeV
  Event-by-event fluctuations in the spatial patterns in charged particles generated in Pb--Pb collisions at the center-of-mass energy $\sqrt{S_{\rm{NN}}}$ = 2.76 TeV are studied within A MultiPhase Transport (AMPT) model. The spatial patterns of the particles generated in the ($\eta, \phi$) space for $|\eta| \le 0.8$ are studied using the methodology of intermittency and erraticity analysis. We find negative intermittency for charged particles generated in a range of $p_{\rm{T}}$ windows. This result contrasts sharply from what is expected for a quark-gluon plasma undergoing hadronization by a second-order phase transition. Appropriate scaling behavior is examined, resulting in definitive scaling exponent $\nu_{-}$. Event-by-event fluctuations in the spatial patterns quantified by an index, named erraticity index are determined for different $p_{\rm{T}}$ bins $\leq 1$ GeV/c, for AMPT model. This is the first time that the intermittency and erraticity indices are determined for any model at such high energies. The results presented here can be used for comparison with the fluctuation properties of the experimental data and hence can help the development of a wider scope of understanding of validity of the particle production process by AMPT at these energies on the one hand, and of the true nature of the real data on the other. 
Ramni Gupta and Rohni Sharma
nucl-ex hep-ph nucl-th