Transverse hydrodynamics with sudden hadronization -- production of strangeness

We consider a physical scenario for ultra-relativistic heavy-ion collisions where, at the early stage, only transverse degrees of freedom of partons are thermalized, while the longitudinal motion is described by free streaming. When the energy density of the partonic system drops to a certain critical value, the partons hadronize and the newly formed hadronic system freezes out. This sudden change is described with the help of the Landau matching conditions followed by the simulations done with THERMINATOR. The proposed scenario reproduces well the transverse-momentum spectra, the elliptic flow coefficient v2, and the HBT radii of pions and kaons studied at RHIC (Au+Au collisions at the top beam energy). It also reproduces quite well the transverse-momentum spectra of hyperons.Comment: talk presented by WF at the Strangeness in Quark Matter Conference, Buzios, Brazil, Sept. 27 - oct. 2, 200

Valuing House and Landscape Attributes: Application of the Hedonic Pricing Technique

Hedonic pricing is used to determine the effect of a landscape element such as the lawn area on the home selling price of single-family homes in Athens, Georgia. Results show that lawn area and the use of zoysiagrass as the dominant species positively and significantly influenced the selling price.Land Economics/Use,

Homogeneous Relaxation at Strong Coupling from Gravity

Homogeneous relaxation is a ubiquitous phenomenon in semiclassical kinetic theories where the quasiparticles are distributed uniformly in space, and the equilibration involves only their velocity distribution. For such solutions, the hydrodynamic variables remain constant. We construct asymptotically AdS solutions of Einstein's gravity dual to such processes at strong coupling, perturbatively in the amplitude expansion, where the expansion parameter is the ratio of the amplitude of the non-hydrodynamic shear-stress tensor to the pressure. At each order, we sum over all time derivatives through exact recursion relations. We argue that the metric has a regular future horizon, order by order in the amplitude expansion, provided the shear-stress tensor follows an equation of motion. At the linear order, this equation of motion implies that the metric perturbations are composed of zero wavelength quasinormal modes. Our method allows us to calculate the non-linear corrections to this equation perturbatively in the amplitude expansion. We thus derive a special case of our previous conjecture on the regularity condition on the boundary stress tensor that endows the bulk metric with a regular future horizon, and also refine it further. We also propose a new outlook for heavy-ion phenomenology at RHIC and ALICE.Comment: 60 pages, a section titled "Outlook for RHIC and ALICE" has been added, accepted for publication in Physical Review

Calculation of Screening Masses in a Chiral Quark Model

We consider a simple model for the coordinate-space vacuum polarization function which is often parametrized in terms of a screening mass. We discuss the circumstances in which the standard result for the screening mass, $m_{sc}=\pi T$, is obtained. In the model considered here, that result is obtained when the momenta in the relevant vacuum polarization integral are small with respect to the first Matsubara frequency.Comment: 6 pages, 2 figure

Resonance Production in RHIC Collisions

Results of resonance particle production measured at RHIC in $\sqrt{s_{\rm NN}} =$ 200 GeV Au+Au collisions are compared to measurements in p+p and d+Au collisions in order to verify the existence of an extended hardronically interacting medium. Yield and momentum distributions of resonances maybe modified during the fireball lifetime due to resonance decay and the subsequent rescattering of their decay daughters as well as the regeneration of resonances from their decay products. Modified momentum spectra in heavy ion collisions may change the nuclear modification factor R$_{\rm AA}$. The influence on the elliptic flow v$_{2}$ due to late regeneration of resonances is discussed.Comment: 6 pages, 6 figures, Proceedings of the 22st Winter Workshop on Nuclear Dynamics, San Diago, California, 12-18 March, 200

Lambda(1520) production in d+Au collisions at RHIC

Recent results of $\Lambda$(1520) resonance production in d+Au collisions at $\sqrt{s_{\rm NN}} =$ 200 GeV are presented and discussed in terms of the evolution and freeze-out conditions of a hot and dense fireball medium. Yields and spectra are compared to results from p+p and Au+Au collisions. The $\Lambda$(1520)/$\Lambda$ ratio in d+Au collisions ratio is consistent with the ratio in p+p collisions. This suggests a short time for elastic interactions between chemical and thermal freeze-out. One can conclude that the interaction volume in d+Au collisions is small.Comment: 4 Pages, 3 figures, conference proceedings Quark Matter 200

Comment on ``Relativistic kinetic equations for electromagnetic, scalar and pseudoscalar interactions''

It is found that the extra quantum constraints to the spinor components of the equal-time Wigner function given in a recent paper by Zhuang and Heinz should vanish identically. We point out here the origin of the error and give an interpretation of the result. However, the principal idea of obtaining a complete equal-time transport theory by energy averaging the covariant theory remains valid. The classical transport equation for the spin density is also found to be incorrect. We give here the correct form of that equation and discuss briefly its structure.Comment: 5 pages LaTe

Particle Ratios as a Probe of the QCD Critical Temperature

We show how the measured particle ratios can be used to provide non-trivial information about the critical temperature of the QCD phase transition. This is obtained by including the effects of highly massive Hagedorn resonances on statistical models, which are used to describe hadronic yields. The inclusion of Hagedorn states creates a dependence of the thermal fits on the Hagedorn temperature, $T_H$, which is assumed to be equal to $T_c$, and leads to an overall improvement of thermal fits. We find that for Au+Au collisions at RHIC at $\sqrt{s_{NN}}=200$ GeV the best square fit measure, $\chi^2$, occurs at $T_c \sim 176$ MeV and produces a chemical freeze-out temperature of 172.6 MeV and a baryon chemical potential of 39.7 MeV.Comment: 6 pages, 4 figure

Strong Color Field Baryonic Remnants in Nucleus-Nucleus Collisions at 200A GeV

The effects of strong color electric fields (SCF) on the baryon production at RHIC are studied in the framework of HIJING/B\=B (v2.0) model. The particle species dependence of nuclear modification factors (NMF) are analyzed for Au+Au collisions at 200A GeV. A doubling of the string tension leading to a modification of the strangeness suppression according to Schwinger mechanism is shown to provide an alternate explanation to coalescence models for the interpretation of the observed baryon and meson production at moderate $p_T$ and results in a predicted enhancement in the (multi)strange (anti)hyperon production.Comment: 6 pages, Latex(Revtex), 4 figures;Added new references, one figure, text slightly modified. final version accepted for publication in Pnys. Rev. C (october,05

Simultaneous Matrix Diagonalization for Structural Brain Networks Classification

This paper considers the problem of brain disease classification based on connectome data. A connectome is a network representation of a human brain. The typical connectome classification problem is very challenging because of the small sample size and high dimensionality of the data. We propose to use simultaneous approximate diagonalization of adjacency matrices in order to compute their eigenstructures in more stable way. The obtained approximate eigenvalues are further used as features for classification. The proposed approach is demonstrated to be efficient for detection of Alzheimer's disease, outperforming simple baselines and competing with state-of-the-art approaches to brain disease classification