124740049
Longitudinal boost invariance of the charge balance function in hadron-hadron and nucleus-nucleus collisions
Using Monte Carlo generators of the PYTHIA model for hadron-hadron collisions and a multiphase transport (AMPT) model for nucleus-nucleus collisions, the longitudinal boost invariance of charge balance function and its transverse-momentum dependence are carefully studied. It shows that the charge balance function is boost invariant in both p+p and Au+Au collisions in these two models, consistent with experimental data. The balance function properly scaled by the width of the pseudorapidity window is independent of the position or the size of the window and is corresponding to the balance function of the whole pseudorapidity range. This longitudinal property of balance function also holds for particles in small transverse-momentum ranges in the PYTHIA and the AMPT default models, but is violated in the AMPT with string melting. The physical origin of the results is discussed.
123369286
Local charge nonequilibrium and anomalous energy dependence of normalized moments in narrow rapidity windows
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.
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.
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.
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.
121493612
GEOMETRICAL DIAGNOSTICS FOR THE NEW AGEGRAPHIC DARK ENERGY MODEL WITH INTERACTION
In this paper, on the basis of Ref. 24 we will further study the new agegraphic dark energy (NADE) model with interaction term Γ = 3b2Hρc. Concretely, not only can the evolutions of some related cosmological quantities be described, but also the two geometrical diagnostic approaches are performed to this model, i.e. statefinder and Om diagnostics. By illustrating the evolutionary trajectories in r-s, r-q, w'-w and Om planes, we find that the constant n and coupling intensity b2 play very important roles in the NADE model, and the Om curves of the NADE model are more sensitive to the constants than ones of the OADE model. In addition, we also plot the LCDM horizonal lines in Om diagrams, and show the discrimination among the NADE, OADE and LCDM models.
121500515
The dynamic evolutions of the generalized Hobbit model and structure formation
In this paper a more general phenomenological model is proposed on the basis of the Hobbit model in Cardone et al. (Phys Rev D 69:083517, 2004). The main purpose of constructing our model is to make this model can not only mimic the ΛCDM model, but also describe a four-phase smooth transition of the universe, namely the inflationary phase, a radiation-dominated phase, a matter-dominated phase and a de Sitter-like phase. In order to check whether this model is a viable one, the evolutions of the universe are respectively discussed in the two cases, and the possible physical interpretations for this model are also respectively shown by using the scalar fields. Finally, the structure formations in our model are simply discussed for the both cases, and the results given by us reconfirm that our model can be regarded as a fit to the ΛCDM model, if we choose the proper conditions.
118408012
Measurement of Cosmic Ray Flux in China JinPing underground Laboratory
China JinPing underground Laboratory (CJPL) is the deepest underground laboratory presently running in the world. In such a deep underground laboratory, the cosmic ray flux is a very important and necessary parameter for rare event experiments. A plastic scintillator telescope system has been set up to measure the cosmic ray flux. The performance of the telescope system has been studied using the cosmic ray on the ground laboratory near CJPL. Based on the underground experimental data taken from November 2010 to December 2011 in CJPL, which has effective live time of 171 days, the cosmic ray muon flux in CJPL is measured to be (2.0+-0.4)*10^(-10)/(cm^2)/(s). The ultra-low cosmic ray background guarantees CJPL's ideal environment for dark matter experiment.
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.
118403322
Reduced modified Chaplygin gas cosmology
A bstractIn this paper, we study cosmologies containing the reduced modified Chaplygin gas (RMCG) fluid which is reduced from the modified Chaplygin gas p = Aρ − Bρ−α for the value of α = −1/2. In this special case, dark cosmological models can be realized for different values of model parameter A. We investigate the viabilities of these dark cosmological models by discussing the evolutions of cosmological quantities and using the currently available cosmic observations. It is shown that the special RMCG model (A = 0 or A = 1) which unifies the dark matter and dark energy should be abandoned. For A = 1/3, RMCG which unifies the dark energy and dark radiation is the favorite model according to the objective Akaike information criteria. In the case of A < 0, RMCG can achieve the features of the dynamical quintessence and phantom models, where the evolution of the universe is not sensitive to the variation of model parameters.