Correlations of conserved charges and QCD phase structure

Correlations of conserved charges,i.e.,the baryon number,electric charge,and strangeness,are calculated at finite temperature and chemical potentials up to the fourth order.The calculations are done ina 2+1 flavor low energy effective theory,in which the quantum and thermal fluctuations are encoded through the evolution of flow equations within the functional renormalization group approach.Strangeness neutrality and a fixed ratio of the electric charge to the baryon number density are implemented throughout the computation.We find that higher-order correlations incorporate more sensitive critical dynamics than the quadratic ones.In addition,a non-monotonic dependence of the fourth-order correlations between the baryon number and strangeness,i.e.,-χ₃₁^BS/χ₂^Sand χ₂₂^BS/χ₂^S,on the collision energy is also observed.     

Reconstruction of baryon number distributions

The maximum entropy method(MEM) and Gaussian process(GP) regression,which are both wellsuited for the treatment of inverse problems,are used to reconstruct net-baryon number distributions based on a finite number of cumulants of the distribution.B ary on number distributions across the chiral phase transition are reconstructed.It is deduced that with the increase of the order of cumulants,distribution in the long tails,i.e.,far away from the central number,would become increasingly important.We ...     

Chiral criticality and glue dynamics

The chiral order-parameter σ field and its higher-order cumulants of fluctuations are calculated within the functional renormalization group approach by adopting the local potential approximation in this study. The influence of glue dynamics on fluctuations of the σ field is investigated, and we find that they are weakly affected. This is in sharp contrast to the baryon number fluctuations, which are sensitive to the glue dynamics and involve information on the color confinement. The implications of our calculated results are discussed from the viewpoint of the theoretical and experimental efforts in the search for the QCD critical end point.