Imprints of energy limitation in transverse momentum distributions of jets

Using a Tsallis nonextensive approach, we analyse distributions of transverse spectra of jets. We discuss the possible influence of energy conservation laws on these distributions. Transverse spectra of jets exhibit a power-law behavior of $1/p_T^n$ with the power indices $n$ similar to those for transverse spectra of hadrons

Correspondence of multiplicity and energy distributions

The evaluation of the number of ways we can distribute energy among a collection of particles in a system is important in many branches of modern science. In particular, in multiparticle production processes the measurements of particle yields and kinematic distributions are essential for characterizing their global properties and to develop an understanding of the mechanism for particle production. We demonstrate that energy distributions are connected with multiplicity distributions by their generating functions.Comment: Matches published versio

Fluctuating initial conditions in heavy-ion collisions from the Glauber approach

In the framework of the Glauber approach we analyze the shape parameters of the early-formed system and their event-by-event fluctuations. We test a variety of models: the conventional wounded nucleon model, a model admixing binary collisions to the wounded nucleons, a model with hot spots, as well as the hot-spot model where the deposition of energy occurs with a superimposed probability distribution. We look in detail at the so-called participant multipole moments, obtained by an averaging procedure where in each event the system is translated to its center of mass and aligned with the major principal axis of the ellipse of inertia. Quantitative comparisons indicate substantial relative effects for eccentricity in variants of Glauber models. On the other hand, the dependence of the scaled standard deviation of the participant eccentricity on the chosen model is weak. For all models the values range from about 0.5 for the central collisions to about 0.3-0.4 for peripheral collisions, both for the gold-gold and copper-copper collisions. They are dominated by statistics and change only by 10-15% from model to model. We provide an approximate analytic expansion for the multipole moments and their fluctuations given in terms of the fixed-axes moments. For central collisions and in the absence of correlations it gives the simple formula for the scaled standard deviation of the participant eccentricity: sqrt(4/pi-1). Similarly, we obtain expansions for the radial profiles of the multipole distributions. We investigate the relevance of the shape-fluctuation effects for jet quenching and find them important only for very central events. Finally, we argue how smooth hydro leads to the known result v_4 ~ v_2^2, and further to the prediction Delta v_4/v_4 = 2 Delta v_2/v_2.Comment: 20 pages, 15 figures, additions include comparison to the CGC result

Single-freeze-out model for ultra relativistic heavy-ion collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV and the LHC proton puzzle

The single-freeze-out model with parametrized hypersurface and flow geometry is employed to analyze the transverse-momentum spectra of hadrons produced in the Pb+Pb collisions at the collision energy of {$\sqrt{s_{\rm NN}}=2.76$ TeV} at the CERN Large Hadron Collider (LHC). With the notable exception for protons and antiprotons, we find a very good agreement between the model results and the data for the measured hadron species. The additional analysis of the HBT radii of pions helps us to select, from several different types of freeze-out studied in this work, the most realistic form of the freeze-out hypersurface. We find that discrepancy ratio between the model and experiment for the proton/antiproton spectra depends on $p_T$, dropping from 2 in the soft region to 1 around $p_T=1.5$ GeV.Comment: 9 pages, 10 figure

Locally anisotropic momentum distributions of hadrons at freeze-out in relativistic heavy-ion collisions

A spheroidal anisotropic local momentum distribution is implemented in the statistical model of hadron production. We show that this form leads to exactly the same ratios of hadronic abundances as the equilibrium distributions, if the temperature is identified with a characteristic transverse-momentum scale. Moreover, to a very good approximation the transverse-momentum spectra of hadrons are the same for isotropic and anisotropic systems, provided the size of the system at freeze-out is appropriately adjusted. We further show that this invariance may be used to improve the agreement between the model and experimental HBT results.Comment: 7 pages, 4 figure