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.
121919817
A Parametric Dynamic Model of Dark Energy
The double complex symmetric gravitational theory is extended to the parametric symmetric gravitational theory by introducing a parameter β. Hence parametric Friedmann–Robertson–Walker equations are obtained and some characters of dark energy in corresponding spaces are discussed by taking different values of β. In our method some previous results can be included as the special case of our results. It is worth noting that some characters of dark energy can be more intuitively described in our model. By analysis, we can predict that the fate of universe would be a Big Rip in the future, and also find that the state parameters for the two different constraint conditions ωΦ are consistent with the present cosmological observations.
121574004
The double coupling of the Ashtekar gravitational field to the Dirac spinoral fields
By introducing the double spacetime manifold, the double gamma matrices and Dirac spinors, the action of the Dirac spinoral fields is doubled. Furthermore, the double coupling of the Dirac fields to the Ashtekar gravitational fields is studied.
116800851
Parametric (Anti-) Self-Dual Variables and a Related Parametric Yang–Mills–Like Action in Four-Dimensional Gravity
Internal and external parametric dualtransformations as well as (anti-) self-dual variablesin four-dimensional gravity are presented in a unifiedway via a parameter. The double complex (anti-)self-dual variables including the double complex Ashtekarvariables are studied by using the double complexfunction method. Concretely, a parametricYang–Mills-like action is proposed and theanalytic continuation from a double action to the Euclidean action isdiscussed. Some results of previous gravitationaltheories are extended to a parametric form.
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.
204012276
Evolution of Holographic Dark Energy in Interacting Modified Chaplygin Gas Model
We investigate the modified Chaplygin gas (MCG) with interaction between holographic dark energy proposed by Li and dark matter. In this model, evolution of the universe is described in detail, which is from deceleration to acceleration. Specifically, the evolutions of related cosmological quantities such as density parameter, the equation of state of holographic dark energy, deceleration parameter and transition redshift are discussed. Moreover, we also give their present values which are consistent with the lately observations. Furthermore, the results given by us show such a model can accommodate a transition of the dark energy from a normal state wX > – 1 to wX < – 1 phantom regimes.
17896194
On the Intermittency and Chaos in High Energy Collisions
It is shown that an event sample from the Monte Carlo simulation of a random cascading \alpha model with fixed dynamical fluctuation strength is intermittent but not chaotic, while the variance of dynamical fluctuation strength in different events will result in both the intermittency and the chaotic behavior. This shows that fractality and chaoticity are two connected but different features of non-linear dynamics in high energy collisions.
8561645
Parton branching in the color mutation model
The soft production problem in hadronic collisions as described in the eikonal color mutation branching model is improved in the way that the initial parton distribution is treated. Furry branching of the partons is considered as a means of describing the nonperturbative process of parton reproduction in the soft interaction. The values of all the moments, {l_angle}n{r_angle} and C{sub q}, for q=2,{hor_ellipsis},5, as well as their energy dependences, can be correctly determined by the use of only two parameters. {copyright} {ital 1999} {ital The American Physical Society}
117033219
Critical behavior of Binder ratios and ratios of higher order cumulants of conserved charges in QCD deconfinement phase transition
Binder liked ratios of baryon number are firstly suggested in relativistic heavy ion collisions. Using 3D-Ising model, the critical behavior of Binder ratios and ratios of high order cumulants of order parameter are fully presented. Binder ratio is shown to be a step function of temperature. The critical point is the intersection of the ratios of different system sizes between two platforms. From low to high temperature through the critical point, the ratios of third order cumulants change their values from negative to positive in a valley shape, and ratios of fourth order cumulants oscillate around zero. The normalized ratios, like the Skewness and Kurtosis, do not diverge with correlation length, in contrary with corresponding cumulants. Applications of these characters in search critical point in relativistic heavy ion collisions are discussed.
119782208
The influence of statistical fluctuations on the erraticity behavior of multiparticle system
Abstract It is demonstrated that in a low-multiplicity sample, the increase of the fluctuation of event factorial moments with decreasing phase-space scale, called “erraticity”, is dominated by the statistical fluctuations. The erraticity behavior observed in the NA27 experiment can be readily reproduced by purely statistical fluctuations. Applying the erraticity analysis to a high-multiplicity sample is, however, recommended and the method is improved for the very-high-multiplicity case.
14219139
Lifetimes and sizes from two particle correlation functions
Abstract We discuss the Yano-Koonin-Podgoretskii (YKP) parametrization of the two-particle correlation function for azimuthally symmetric expanding sources. We derive model-independent expressions for the YKP fit parameters and discuss their physical interpretation. We use them to evaluate the YKP fit parameters and their momentum dependence for a simple model for the emission function and propose new strategies for extracting the source lifetime. Longitudinal expansion of the source can be seen directly in the rapidity dependence of the Yano-Koonin velocity.