Universal scaling of non-equilibrium critical fluctuations from Langevin dynamics of model A

Within the framework of the Kibble-Zurek Mechanism, we investigate the universal behavior of the non-equilibrium critical fluctuations, using the Langevin dynamics of model A. With properly located typical time, length and angle scales, \tau_{\mbox{KZ}}, l_{\mbox{KZ}}, and \theta_{\mbox{KZ}}, the constructed functions \bar{f}_n((\tau-\tau_c)/\tau_{\mbox{KZ}},\theta_{\mbox{KZ}}) (n=1...4) for the cumulants of the sigma field show universal behavior near the critical point, which are independent from some non-universal factors, such as the relaxation time or the evolution trajectory.Comment: 6 pages, 3 figures, CPOD 2017 proceeding

Dynamical fluctuations in critical regime and across the 1st order phase transition

In this proceeding, we study the dynamical evolution of the sigma field within the framework of Langevin dynamics. We find that, as the system evolves in the critical regime, the magnitudes and signs of the cumulants of sigma field, $C_{3}$ and $C_{4}$, can be dramatically different from the equilibrated ones due to the memory effects near $T_c$. For the dynamical evolution across the 1st order phase transition boundary, the supercooling effect leads the sigma field to be widely distributed in the thermodynamical potential, which largely enhances the cumulants $C_3, \ C_4$, correspondingly.Comment: 4 pages, 2 figures, proceedings for Quark Matter 201

Enhancements of high order cumulants across the 1st order phase transition boundary

In this proceeding, we investigate the dynamical evolution of the $\sigma$ field with a trajectory across the 1st order phase transition boundary, using Langevin dynamics from the linear sigma model. We find the high order cumulants of the $\sigma$ field are largely enhanced during the dynamical evolution, compared with the equilibrium values, due to the supercooling effect of the first order phase transition.Comment: 4 pages, 2 figures, SQM proceeding, with minor change

Dynamical critical fluctuations near the QCD critical point with hydrodynamic expansion rate

In this paper, we investigate the critical slowing down effects on the critical fluctuations driven by the expanding quark-gluon plasma with a trajectory and expanding rate obtained from hydrodynamics. Within model A, we numerically solved the Langevin dynamics of the non-conserved order parameter field and find that, compared with commonly used Hubble-like expansion, the expansion rate of a realistic hydrodynamic system is pretty large and the associated critical slowing down effects strongly suppress the higher-order cumulants. For an evolving system that approaches the critical point, such critical slowing down suppression overcomes the enhancement of the critical fluctuations, which indicates that the observed maximum fluctuations do not necessarily associate with the evolving trajectory closest to the critical point.Comment: 7 pages,5 figure

Collective flow and the fluid behavior in p/d/3^3He+Au collisions at sNN=200\sqrt{s_{NN}} = 200 GeV

By varying the intrinsic initial geometry, the p/d/$^3$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) provide a unique opportunity to understand the collective behavior in the small systems. In this paper, we employ the hybrid model iEBE-VISHNU with TRENTO initial conditions to study the collective flow and the fluid behavior in p/d/$^3$He+Au collisions. With fine-tuned parameters, iEBE-VISHNU can describe the $v_2(p_T)$ and $v_3(p_T)$ data from the PHENIX and STAR collaborations. However, for these parameter sets tuned to fit the STAR data, the hydrodynamic simulations have already beyond their limits with the average Knudsen number $\langle K_n \rangle$ obviously larger than one. Our calculations demonstrate that, for a meaningful evaluation of the fluid behavior in the small systems, model simulations should also pay attention to the validity range of hydrodynamics

Spatiotemporal expression of histone acetyltransferases, p300 and CBP, in developing embryonic hearts

Histone acetyltransferases (HATs), p300 and cAMP response element binding protein (CREB)-binding protein (CBP) are two structurally related transcriptional co-activators that activate expression of many eukaryotic genes involved in cellular growth and signaling, muscle differentiation and embryogenesis. However, whether these proteins play important and different roles in mouse cardiogenesis is not clear. Here, we investigate the protein distributions and mRNA expression of the two HATs in embryonic and adult mouse heart during normal heart development by using immunohistochemical and RT-PCR techniques. The data from immunohistochemical experiments revealed that p300 was extensively present in nearly every region of the hearts from embryonic stages to the adulthood. However, no CBP expression was detected in embryonic hearts at day E7.5. CBP expression appeared at the later stages, and the distribution of CBP was less than that of p300. In the developmental hearts after E10.5, both for p300 and CBP, the mRNA expression levels reached a peak on day E10.5, and then were gradually decreased afterwards. These results reveal that both p300 and CBP are related to embryonic heart development. The dynamic expression patterns of these two enzymes during mouse heart development indicate that they may play an important role on heart development. However, there is a difference in spatiotemporal expression patterns between these two enzymes during heart development. The expression of p300 is earlier and more predominate, suggesting that p300 may play a more important role in embryonic heart development especially during cardiac precursor cell induction and interventricular septum formation