Color Decoherence in In-Medium QCD Cascades

The talk, based on \cite{LN10}, analyzes the consequences of the assumption that the effects of quantum coherence and the resulting angular ordering in QCD cascades are disrupted within the hot fireball created in ultrarelativistic heavy ion collisions.Comment: Presented at Hard Probes 2010, Eilat, Israe

Decoherence and energy loss in QCD cascades in nuclear collisions

The medium modifications in the properties of QCD cascades are considered. In particular, the changes in the intrajet rapidity distributions due to medium-induced decoherence, collisional losses of cascade gluons and those of final prehadrons are analyzed

Local equilibrium of the quark-gluon plasma

Within kinetic theory, we look for local equilibrium configurations of the quark-gluon plasma by maximizing the local entropy. We use the well-established transport equations in the Vlasov limit, supplemented with the Waldmann-Snider collision terms. Two different classes of local equilibrium solutions are found. The first one corresponds to the configurations that comply with the so-called collisional invariants. The second one is given by the distribution functions that cancel the collision terms, representing the most probable binary interactions with soft gluon exchange in the t-channel. The two sets of solutions agree with each other if we go beyond these dominant processes and take into account subleading quark-antiquark annihilation/creation and gluon number non-conserving processes. The local equilibrium state appears to be colorful, as the color charges are not locally neutralized. Properties of such an equilibrium state are analyzed. In particular, the related hydrodynamic equations of a colorful fluid are derived. Possible neutralization processes are also briefly discussed.Comment: 20 pages; minor changes, to be published in Phys. Rev.

The Ter-Mikayelian Effect on QCD Radiative Energy Loss

The color dielectric modification of the gluon dispersion relation in a dense QCD medium suppresses both the soft and collinear gluon radiation associated with jet production. We compute both the longitudinal and transverse plasmon contributions to the zeroth order in opacity radiative energy loss. This QCD analog of the Ter-Mikayelian effect in QED leads to $\sim 30$ reduction of the energy loss of high transverse momentum charm quarks produced in a QCD plasma with a characteristic Debye mass $\mu\sim 0.5$ GeV.Comment: 18 Pages, 16 Figure

Yb(II) Triple-Decker Complex with the μ-Bridging Naphthalene Dianion [CpBn5Yb(DME)]2(μ-η4:η4-C10H8). Oxidative Substitution of [C10H8]2- by 1,4-Diphenylbuta-1,3-diene and P4 and Protonolysis of the Yb-C10H8 Bond by PhPH2

International audienceTwo synthetic approaches to the new three-decker Yb(II) complex [CpBn5Yb(DME)]2[μ-C10H8] (1) were successfully employed: the reaction of [CpBn5Yb(DME)(μ-I)]2 (2) with 2 molar equiv of [C10H8]-·K in DME and the reaction of [YbI(DME)2]2[μ-C10H8] (3) with CpBn5K in a 1:2 molar ratio in DME. Complex 1 was proved to be a Yb(II) binuclear triple-decker complex containing a dianionic naphthalene ligand bridging two CpBn5Yb(DME) fragments in a μ- η4:η4 fashion. An oxidative substitution of (C10H8)2- by trans-(1E,3E)-1,4-diphenylbuta-1,3-diene afforded the three-decker Yb(II) complex [CpBn5Yb(DME)]2(μ- η4:η4 -PhCHCHCHCHPh) (4) with a dianionic μ- η4:η4-bridging diphenylbutadiene ligand and naphthalene. The reaction of 1 with excess P4 also occurs with oxidation of (C10H8)2-, whereas Yb remains divalent. The reaction results in the formation of the trinuclear Yb(II) complex with a μ-bridging P7 3- ligand [CpBn5Yb(DME)]3(P7) (5). Protonation of the Yb-C10H8 bond in 1 with PhPH2 (1:2 molar ratio) afforded the dimeric phosphido complex [CpBn5Yb(THF)(μ2-PHPh)]2 (6) in 64% yield, while an attempt to obtain a phosphinidene Yb(II) species by reacting equimolar amounts of 1 and PhPH2 in DME resulted in the isolation of the metallocene complex CpBn5 2Yb(DME) (7). © 2016 American Chemical Society