119275903
Lifshitz effects on holographic p-wave superfluid
Abstract In the probe limit, we numerically build a holographic p -wave superfluid model in the four-dimensional Lifshitz black hole coupled to a Maxwell-complex vector field. We observe the rich phase structure and find that the Lifshitz dynamical exponent z contributes evidently to the effective mass of the matter field and dimension of the gravitational background. Concretely, we obtain that the Cave of Winds appeared only in the five-dimensional anti-de Sitter (AdS) spacetime, and the increasing z hinders not only the condensate but also the appearance of the first-order phase transition. Furthermore, our results agree with the Ginzburg–Landau results near the critical temperature. In addition, the previous AdS superfluid model is generalized to the Lifshitz spacetime.
121684801
THE VARIABLE GENERALIZED CHAPLYGIN GAS MODEL WITH INTERACTION
In this paper a variable generalized Chaplygin gas (VGCG) proposal for unification of dark matter and dark energy is considered, in which dark energy interacts with dark matter. The equation of state of the VGCG is given by p = -A0a-n/ρα, where a is the scale factor. By calculations some cosmological quantities such as density parameters of baryons, dark matter and dark energy as well as the deceleration parameter are all obtained. Furthermore, the transition from deceleration to acceleration is described and the interaction between dark energy and dark matter is considered in this model. We find the behavior of VGCG is similar to dust-like matter at early times and will be quintessence or phantom at late stage. In addition the evolution trajectory of the VGCG model in the statefinder parameter s-r plane is plotted and the discrimination between this scenario and the generalized Chaplygin gas (GCG) model is illustrated.
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.
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.
118457694
Combined constraints on modified Chaplygin gas model from cosmological observed data: Markov Chain Monte Carlo approach
We use the Markov Chain Monte Carlo method to investigate a global constraints on the modified Chaplygin gas (MCG) model as the unification of dark matter and dark energy from the latest observational data: the Union2 dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. In a flat universe, the constraint results for MCG model are, $${\Omega_{b}h^{2}\,{=}\,0.02263^{+0.00184}_{-0.00162} (1\sigma)^{+0.00213}_{-0.00195} (2\sigma)}$$, $${B_{s}\,{=}\,0.7788^{+0.0736}_{-0.0723}(1\sigma)^{+0.0918}_{-0.0904} (2\sigma)}$$, $${\alpha\,{=}\,0.1079^{+0.3397}_{-0.2539} (1\sigma)^{+0.4678}_{-0.2911} (2\sigma)}$$, $${B\,{=}\,0.00189^{+0.00583}_{-0.00756}(1\sigma)^{+0.00660}_{-0.00915} (2\sigma)}$$, and $${H_{0}=70.711^{+4.188}_{-3.142} (1\sigma)^{+5.281}_{-4.149}(2\sigma)}$$.
122914830
THE MODIFIED CHAPLYGIN GAS AS A UNIFIED DARK SECTOR MODEL
A modified Chaplygin gas (MCG) model of unifying dark energy and dark matter is considered in this paper. Concretely, the evolution of such a unified dark sector model is studied and the statefinder diagnostic to the MCG model is performed in our model. By analysis, it is shown that the state parameter of dark energy can cross the so-called phantom divide ω = -1, the behavior of MCG will be like ΛCDM in the future and therefore our universe will not end up with Big Rip in the future. In addition, we plot the evolution trajectory of the MCG model in the statefinder parameter r–s plane and show the discrimination between this scenario and other dark energy models.
120731900
On the random cascading model study of anomalous scaling in multiparticle production with continuously diminishing scale
The anomalous scaling of factorial moments with continuously diminishing scale is studied using a random cascading model. It is shown that the model currently used have the property of anomalous scaling only for descrete values of elementary cell size. A revised model is proposed which can give good scaling property also for continuously varying scale. It turns out that the strip integral has good scaling property provided the integral regions are chosen correctly, and that this property is insensitive to the concrete way of self-similar subdivision of phase space in the models.
53370258
Two-particle azimuthal angle correlations and azimuthal charge balance function in relativistic heavy ion collisions
The two-particle azimuthal angle correlation (TPAC) and azimuthal charge balance function (ACBF) are used to study the anisotropic expansion in relativistic heavy ion collisions. It is demonstrated by the relativistic quantum molecular dynamics (RQMD) model and a multi-phase transport (AMPT) model that the small-angle correlation in TPAC indeed presents anisotropic expansion, and the large-angle (or back-to-back) correlation is mainly due to global momentum conservations. The AMPT model reproduces the observed TPAC, but the RQMD model fails to reproduce the strong correlations in both small and large azimuthal angles. The width of ACBF from RQMD and AMPT models decreases from peripheral to central collisions, consistent with experimental data, but in contrast to the expectation from thermal model calculations. The ACBF is insensitive to anisotropic expansion. It is a probe for the mechanism of hadronization, similar to the charge balance function in rapidity.
1326666
Critical behavior of hadronic fluctuations and the effect of final-state randomization
The critical behaviors of the quark-hadron phase transition are explored by use of the Ising model adapted for hadron production. Various measures involving the fluctuations of the produced hadrons in bins of various sizes are examined with the aim of quantifying the clustering properties that are universal features of all critical phenomena. Some of the measures involve wavelet analysis. Two of the measures are found to exhibit the canonical power-law behavior near the critical temperature. The effect of final-state randomization is studied by requiring the produced particles to take random walks in the transverse plane. It is demonstrated that for the measures considered the dependence on the randomization process is weak. Since temperature is not a directly measurable variable, the average hadronic density of a portion of each event is used as the control variable that is measurable. The event-to-event fluctuations are taken into account in the study of the dependence of the chosen measures on that control variable. Phenomenologically verifiable critical behaviors are found and are proposed for use as a signature of quark-hadron phase transition in relativistic heavy-ion collisions.
122405855
Erraticity analysis of multiparticle production in π+p and K+p collisions at 250 GeV/c
Abstract The erraticity behavior of multiparticle production is analyzed in π + p and K + p collisions at 250 GeV/ c . It is demonstrated that, for these low-multiplicity final states, the erraticity measure based on event-to-event fluctuation of factorial moments is dominated by statistical fluctuations.
119487881
ON THE RELATION BETWEEN MULTIPLICITY AND TRANSVERSE ENERGY IN HIGH ENERGY HADRON-HADRON AND NUCLEUS-NUCLEUS COLLISIONS
The relation between multiplicity and transverse energy in high energy h-h and A-A collisions is investigated using a Monte Carlo generator of nondiffractive processes. The width of multiplicity fluctuation D/ for fixed E⊥ is found to be small and approximately constant for a wide range of E⊥.