118647633
Trace initial interaction from final state observable in relativistic heavy ion collisions
sNN = 200 GeV by using the Monte Carlo models RQMD with hadron re-scattering and AMPT with and without string melting, we observe that the correlation patterns change gradually from out-of-plane preferential one to in-plane preferential one when the centrality of collision shifts from central to peripheral, meanwhile the anisotropic collective flow v2 keeps positive in all cases. This regularity is found to be model and collision energy independent. The physics behind the two opposite trends of correlation patterns, in particular, the presence of out-of-plane correlation patterns at RHIC energy, are discussed.
118547741
Statistical and dynamical fluctuations of Binder ratios in heavy ion collisions
Higher moments of the net-proton Binder ratio, which is suggested to be a good observation to locate the QCD critical point, is measured in relativistic heavy ion collisions. We first estimate the effect of statistical fluctuations of the third- and fourth-order Binder ratios. Then the dynamical Binder ratio is proposed and investigated in both transport and statistical models. The energy dependence of dynamical Binder ratios with different system sizes at RHIC beam scan energies is presented and discussed.
120866499
FRACTALITY IN ELEMENTARY COLLISIONS
Different fractality in hadron–hadron and e+e- collisions and its experimental observation are reviewed. The discussions on related underlying dynamics are presented.
116833066
Locating the critical point of QCD phase transition by finite-size scaling
It is pointed out that in relativistic heavy ion collisions, critical related observable in the vicinity of critical point should follow finite-size scaling. The methods of finding and locating critical point are established for the first time by finite-size scaling and its critical characteristics, in particular, the fixed-point and straight-line behavior. As an application of the method, the critical behavior at RHIC data is demonstrated.
123369286
Local charge nonequilibrium and anomalous energy dependence of normalized moments in narrow rapidity windows
16991538
On the Dominance of Statistical Fluctuation in the Factorial-Moment Study of Chaos in Low Multiplicity Events of High Energy Collisions
It is shown using Monte Carlo simulation that for low multiplicity events the single-event factorial moments are saturated by the statistical fluctuations. The diverse of the event-space moments $C_{p,q}$ of single-event moments with the diminishing of phase space scale, called ``erraticity'', observed in experiment can readily be reproduced by a flat probability distribution with only statistical fluctuations and therefore does not indicate the existence of chaos as suggested. The possibility of studying chaos in high multiplicity events using erraticity analysis is discussed.
120274935
THE EVOLUTION OF GENERALIZED CHAPLYGIN GAS
We consider the generalized Chaplygin gas (GCG) proposal for the unification of dark matter and dark energy with p = pde and ρ = ρdm+ρde. The unified equation of state for GCG has been obtained: . On the basis of the function χ(z), some cosmological quantities such as the fractional contributions of different components of the universe Ωi (i respectively denotes baryons, dark matter and dark energy) to the critical density, the equation of state for dark energy ωde, the deceleration parameter q are all obtained, which are consistent with observations. In addition, the transition from deceleration to acceleration is described in our model. We find that the behavior of GCG will be like ΛCDM in the future. So, it has been ruled out in our model that our universe will end up with Big Rip in the future.
123064936
An interacting dark energy model in a non-flat universe
In this paper, an interacting dark energy model in a non-flat universe is studied, with taking interaction form $$C=\alpha H\rho _{de}$$C=αHρde. And in this study a property for the mysterious dark energy is aforehand assumed, i.e. its equation of state $$w_{\Lambda }=-1$$wΛ=-1. After several derivations, a power-law form of dark energy density is obtained $$\rho _{\Lambda } \propto a^{-\alpha }$$ρΛ∝a-α, here $$a$$a is the cosmic scale factor, $$\alpha $$α is a constant parameter introducing to describe the interaction strength and the evolution of dark energy. By comparing with the current cosmic observations, the combined constraints on the parameter $$\alpha $$α is investigated in a non-flat universe. For the used data they include: the Union2 data of type Ia supernova, the Hubble data at different redshifts including several new published datapoints, the baryon acoustic oscillation data, the cosmic microwave background data, and the observational data from cluster X-ray gas mass fraction. The constraint results on model parameters are $$\Omega _{K}=0.0024\,(\pm 0.0053)^{+0.0052+0.0105}_{-0.0052-0.0103}, \alpha =-0.030\,(\pm 0.042)^{+0.041+0.079}_{-0.042-0.085}$$ΩK=0.0024(±0.0053)-0.0052-0.0103+0.0052+0.0105,α=-0.030(±0.042)-0.042-0.085+0.041+0.079 and $$\Omega _{0m}=0.282\,(\pm 0.011)^{+0.011+0.023}_{-0.011-0.022}$$Ω0m=0.282(±0.011)-0.011-0.022+0.011+0.023. According to the constraint results, it is shown that small constraint values of $$\alpha $$α indicate that the strength of interaction is weak, and at $$1\sigma $$1σ confidence level the non-interacting cosmological constant model can not be excluded.
122648799
STUDY ON A UNIFIED MODEL OF DARK MATTER AND DARK ENERGY FROM DBI THEORY
In this paper, we study a unified model of dark matter and dark energy obtained from Dirac–Born–Infeld (DBI) action in string theory. Two accelerated expansions in universe can be unified in this action. By using the Markov Chain Monte Carlo method, we fit the current observational data to constrain the model parameters in this unified model, where various density parameters as model parameters are included, and their constraint values are: , , and . In addition, the Hubble constant and cosmic age are and (Gyr), respectively. According to the constraint results on model parameters we discuss the evolutions of some cosmological quantities in structure formation, such as the density contrast and the growth variable. At last, the evolution of geometrical quantity is studied to distinguish the unified models of dark sectors with the cosmological constant model. It is shown that this unified model of dark matter and dark energy is attractive to interpret the accelerating universe.
119108135
Lifshitz Scaling Effects on Holographic Superconductors
Via numerical and analytical methods, the effects of the Lifshitz dynamical exponent z on the holographic superconductor models are studied in some detail, including s-wave and p-wave models. Working in the probe limit, we calculate the condensation and conductivity in both Lifshitz black hole and soliton backgrounds with a general z. For both the s-wave and p-wave models in the black hole backgrounds, as z increases, the phase transition becomes difficult and the conductivity is suppressed. For the Lifshitz soliton background, when z increases, the critical chemical potential increases in both the s-wave model (with a fixed mass of the scalar field) and p-wave model. For the p-wave model in both the Lifshitz black hole and soliton backgrounds, the anisotropy between the AC conductivity in different spatial directions is suppressed when z increases. In all cases, we find that the critical exponent of the condensation is always 1/2, independent of z and spacetime dimension. The analytical results from the Sturm-Liouville variational method uphold the numerical calculations. The implications of these results are discussed. (C) 2014 The Authors. Published by Elsevier B.V.
122877762
Analysis on modified Chaplygin gas as dark energy model
In this paper, we will continue to study the modified Chaplygin gas (MCG) based on Ref. 25. Concretely, we not only discuss both the change rates of the energy densities and the Hubble parameter H(z) as a function of the model parameters, which is compared and consistent with the related data in Ref. 27, but also perform the Om diagnostic in order to geometrically differentiate the MCG model from the ΛCDM, GCG and CG models. Moreover, we plot the evolutionary trajectories of MCG model with different interaction terms in Om planes, and find that the coupling intensity b2 plays an important role in the MCG model. Furthermore, we also reconstruct the potential of MCG scalar field as well as the dynamics of the scalar field according to the evolution of the MCG dark energy. It is worth stressing that the results given by us can include the ones without interaction as the special cases.