121991332
RAPIDITY DEPENDENCE OF CHARGE FLUCTUATIONS AND CORRELATIONS IN HADRONIC AND NUCLEAR COLLISIONS
Size and position of rapidity window dependence of charge fluctuations and correlations are studied by PYTHIA and RQMD models for hadron–hadron and nucleus–nucleus collisions respectively. The results show that all the measures for charge fluctuations and correlations depend on the size of central rapidity windows and most of them depend on the position of the rapidity windows, which is not expected. Only charge balance function in hadron–hadron collisions is independent of the position of rapidity window, i.e. boost-invariant, in consistent with corresponding experimental data, while charge fluctuations measured by D(Q) is not boost-invariant in contrast to the experimental data. The measures for three kind of charge correlations (R++, R--, R+-) show a good account for the behavior of charge correlations and global charge conservation in longitudinal phase space in both PYTHIA and RQMD.
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.
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.
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.
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.
123369286
Local charge nonequilibrium and anomalous energy dependence of normalized moments in narrow rapidity windows
123490615
COSMOLOGICAL EVOLUTION OF MODIFIED CHAPLYGIN GAS INTERACTING WITH BAROTROPIC BACKGROUND FLUID
Based on the observation that the equation of state parameter ω can cross the phantom dividing ω = -1 and has a 99% probability of being ω < -1, we introduce an interaction between the modified Chaplygin gas and the barotropic background fluid. By studying the dynamical evolution of the MCG model with interaction and the statefinder diagnostic in autonomous system, we find that the MCG vacuum-energy-dominated phase is the only stable attractor, the universe evolves from the matter-dominated phase to the MCG vacuum-energy-dominated phase, and the effect of the transfer strength parameter c is evident. In addition, we have plotted the evolution trajectories of the interacting CG, GCG and MCG models with barotropic background fluid in the statefinder parameter (s - r)-plane to illustrate the discriminations among these scenarios.
118477157
TIME VARIABLE COSMOLOGICAL CONSTANT OF HOLOGRAPHIC ORIGIN WITH INTERACTION IN BRANS–DICKE THEORY
Time variable cosmological constant (TVCC) of holographic origin with interaction in Brans–Dicke theory is discussed in this paper. We investigate some characters for this model, and show the evolutions of deceleration parameter and equation of state (EOS) for dark energy. It is shown that in this scenario an accelerating universe can be obtained and the evolution of EOS for dark energy can cross over the boundary of phantom divide. In addition, a geometrical diagnostic method, jerk parameter, is applied to this model to distinguish it with cosmological constant.
118569311
Modified f(G) gravity models with curvature–matter coupling
A modified f(G) gravity model with coupling between matter and geometry is proposed, which is described by the product of the Lagrange density of the matter and an arbitrary function of the Gauss–Bonnet term. The field equations and the equations of motion corresponding to this model show the non-conservation of the energy-momentum tensor, the presence of an extra force acting on test particles and non-geodesic motion. Moreover, the energy conditions and the stability criterion at the de Sitter point in modified f(G) gravity models with curvature–matter coupling are derived, which can degenerate to the well-known energy conditions in general relativity. Furthermore, in order to get some insight in the meaning of these energy conditions, we apply them to the specific models of f(G) gravity and the corresponding constraints on the models are given. In addition, the conditions and the candidate for late-time cosmic accelerated expansion in modified f(G) gravity are studied by means of conditions of power-law expansion and the equation of state of matter ω smaller than $-\frac{1}{3}$.
122566445
CONSTRAINT ON THE KINEMATICAL AND DYNAMICAL MODEL FROM THE LATEST OBSERVATIONAL DATA
The kinematical model j(z) = j0 and dynamical model wde(z) = w0, are constrained from the latest observational data: Union2 data including 557 type Ia supernovae (SNIa), 15 observational Hubble data (OHD), baryon acoustic oscillation (BAO) data from Sloan Digital Sky Survey (SDSS) and Two-degree Field Galaxy Redshift Survey (2dFGRS) and CMB data from seven-year WMAP. We get the current values of deceleration parameter q0, jerk parameter j0, dimensionless matter density Ωm, equation of state for dark energy w0 and transition redshift zT. Furthermore, it is shown that for both kinematical and dynamical models, the constraint results support for the cosmic concordance model, ΛCDM.
119216015
More on QCD ghost dark energy
The difference between the vacuum energy of quantum fields in Minkowski space and in a Friedmann-Robertson-Walker universe might be related to the observed dark energy. The vacuum energy of the Veneziano ghost field introduced to solve the U(1)(A) problem in QCD is of the form H + O(H-2). Based on this, we study the dynamical evolution of a phenomenological dark energy model whose energy density is of the form alpha H + beta H-2. In this model, the universe approaches a de Sitter phase at late times. We fit the model with current observational data, including SnIa, BAO, CMB, BBN, the Hubble parameter, and the growth rate of matter perturbation. It shows that the universe begins to accelerate at redshift z similar to 0.75, and this model is consistent with current data. In particular, this model fits the data of the growth factor well as the Lambda CDM model.