Linear maps on the space of all bounded observables preserving maximal deviation

In this paper we determine all the bijective linear maps on the space of bounded observables which preserve a fixed moment or the variance. Nonlinear versions of the corresponding results are also presented.Comment: 27 pages. To appear in J. Funct. Ana

The fate of the Mach cone in covariant transport theory

An intriguing potential signature of hydrodynamic behavior in relativistic A+A reactions at Relativistic Heavy Ion Collider (RHIC) energies is conical flow induced by fast supersonic particles traversing the hot and dense medium. Here I present first results on the evolution of Mach shocks in 2->2 covariant transport theory, in a static uniform medium.Comment: Presentation at CIPANP 2009 (Tenth Conference on the Intersections of Particle and Nuclear Physics), May 26-31, 2009, Torrey Pines, California, US

Freeze out in narrow and wide layers

The freeze out of particles from a layer of finite thickness is discussed in a phenomenological kinetic model. The proposed model, based on the Modified Boltzman Transport Equation, is Lorentz invariant and can be applied equally well for the freeze out layers with space-like and time-like normal vectors. It leads to non-equilibrated post freeze out distributions. The dependence of the resulting distribution on the thickness of the layer is presented and discussed for a space-like freeze out scenario.Comment: Minor corrections to improve the presentation. 4 pages, 2 figures, to appear in the Proceedings of "Quark Matter 2005", August 4-9, 2005, Budapest, Hungar

Effects of Multiple Scattering in Cold Nuclear Matter on J/psi Suppression and <p_T^2> in Heavy Ion Collisions

Coherent multiple scatterings of c and cbar quark pairs in the environment of heavy ion collisions have been used in a previous work by Qiu et al. [Qiu:1998rz] to study J/psi suppression. That model suggests that heavy quark re-scatterings in a cold nuclear medium can completely explain the centrality dependence of the observed J/psi suppression in Pb+Pb collisions at the SPS [Abreu:2001kd]. Their calculations also revealed significant differences under the assumptions of a color singlet or color octet production mechanism. A more recent analytic calculation [Fujii:2003fq], which includes incoherent final-state re-scatterings with explicit momentum transfer fluctuations in three dimensions, indicates much less suppression and little sensitivity to the production mechanism. In this article, we study simultaneously both the J/psi suppression and p_T modifications, at SPS and RHIC energies. We mainly focus on incoherent momentum transfer fluctuations in two dimensions, which is more appropriate for the heavy-ion collision kinematics. Our analytic and Monte-Carlo calculations reinforce the analytic results in [Fujii:2003fq]. Additionally, we find that the experimental J/psi suppression and from nucleus-nucleus collisions at the SPS or RHIC cannot simultaneously be described in this incoherent multiple scattering framework for any value of the fluctuation strength parameter .Comment: 8 pages, 6 figures, submitted for publication; v2:10 pages, 7 figures, accepted for publication in Physics Letters B Added comparison with SPS p+A dat

Covariant kinetic freeze out description through a finite space-time layer

We develop and analyze a covariant FO probability valid for a finite space-time layer.Comment: Proceedings of "Quark Matter 2005", 4 pages, 3 figures, with correction

Jet-like correlations between Forward- and Mid- rapidity in p+p, d+Au and Au+Au collisions from STAR at 200 GeV

In this proceedings we present STAR measurements of two particle azimuthal correlations between trigger particles at mid-rapidity ($|\eta|<$ 1) and associated particles at forward rapidities (2.7 $<|\eta|<$ 3.9) in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV. Two particle azimuthal correlations between a mid-rapidity trigger particle and forward-rapidity associated particles preferably probe large-x quarks scattered off small-x gluons in RHIC collisions. Comparison of the separate d- and Au-side measurements in d+Au collisions may potentially probe gluon saturation and the presence of Color Glass Condensate. In Au+Au collisions quark energy loss can be probed at large rapidities, which may be different from gluon energy loss measured at mid-rapidity.Comment: Quark Matter 06 Conference proceedings, submitted to Journal of Phys.

THE WETTABILITY OF A DNAPL/SURFACTANT SOLUTION ON QUARTZ AND IRON OXIDE SURFACES

DNAPLs in the subsurface may contain surface-active compounds that impact DNAPL migration and distribution. A number of studies to-date have focused on the role surface active compounds play in altering the wettability of quartz sands without examining the implications for other minerals commonly present in the subsurface. This study aims to extend the understanding of DNAPL/surfactant wettability to iron oxide surfaces. Specifically the objective was to compare the changes in the wettability of quartz and iron oxide sands in a tetrachloroethylene/water system containing a representative organic base. Wettability was assessed through: contact angles; Pc-S curves; and a two- dimensional flow cell experiment. It was discovered that quartz and iron oxide surfaces may exhibit different wetting characteristics under similar subsurface conditions. At neutral pH the quartz was strongly NAPL-wetting while the iron oxide remained hydrophilic. This study concludes that the isoelectric point, the pH at which there is a net zero surface charge, plays a major role in governing cationic surfactant sorption