Jet Studies in STAR via Di-jet Triggered (2+1) Multi-hadron Correlations

We explore jet-medium interactions via the recently developed multi-hadron correlation or "2+1" technique. We restrict the di-jet kinematics by selecting a pair of approximately back-to-back high pT hadron triggers and study associated particles. Here we present our study of di-jet systematics comparing the measurements of associate yields and spectra in 200 GeV Au+Au and d+Au collisions in two different scenarios. We present Sum(pT) as an estimate for energy loss. First findings indicate little to no energy loss in the symmetric "2+1" scenario whereas model predictions are about 2 GeV.Comment: 4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

Three-Particle Azimuthal Correlations

Two-particle azimuthal correlations in central Au+Au collisional at RHIC have revealed a broadened away-side structure, with respect to perpherial Au+Au, pp, and d+Au. This could be explained by different physics mechanisms such as: large angle gluon radiation, deflected jets, Cerenkov gluon radiation, and conical flow generated by hydrodynamic shock-waves. We can discriminate the scenarios with conical emission, Cerenkov radiation and conical flow, from the other mechanisms though three-particle correlations. In addition, the associated particle pT dependence can be used to distinguish conical flow from simple Cerenkov gluon radiation. We will discuss three-particle correlation analyses that have been performed at RHIC and what can be done at the LHC.Comment: Talk given at 'High p_T physics at the LHC', Jyvaskyla, Finland, March 200

Cumulant versus jet-like three-particle correlations

Two-particle jet-like azimuthal correlations have revealed intriguing modifications to the away-side of high pt trigger particles in relativistic heavy-ion collisions. Three-particle jet-like azimuthal correlation and three-particle azimuthal cumulant have been analyzed in experiments in attempt to distinguish conical emission of jet-correlated particles from other physics mechanisms. We investigate the difference between three-particle jet-like correlation and three-particle cumulant in azimuth. We show, under the circumstance where the away-side two-particle correlation is relatively flat in azimuth and similar in magnitude to the azimuthal average of the two-particle correlation signal, that the three-particle cumulant cannot distinguish conical emission from other physics mechanisms. The three-particle jet-like correlation, on the other hand, retains its discrimination power.Comment: 13 pages, 8 figures. published versio

Analysis Method for Jet-Like Three-Particle Azimuthal Correlations

Jet-like three-particle azimuthal correlations can discriminate various physical scenarios that have been proposed to explain the observed strong modification to two-particle azimuthal correlations. The three-particle correlation analysis is notoriously difficult in heavy-ion collisions due to the large combinatoric backgrounds. We describe the general idea behind the jet-like three-particle azimuthal correlation analysis, with emphasis put on the subtraction of the combinatoric backgrounds. We discuss in detail the various systematic effects in such an analysis.Comment: This is the final published version in NIM

Evangelical Visitor - March 29, 1943 Vol. LVI. No. 7.

Vol. LVI. No. 7

Energy deposition in hard dihadron triggered events in heavy-ion collisions

The experimental observation of hadrons correlated back-to-back with a (semi-)hard trigger in heavy ion collisions has revealed a splitting of the away side correlation structure in a low to intermediate transverse momentum (P_T) regime. This is consistent with the assumption that energy deposited by the away side parton into the bulk medium produced in the collision excites a sonic shockwave (a Mach cone) which leads to away side correlation strength at large angles. A prediction following from assuming such a hydrodynamical origin of the correlation structure is that there is a sizeable elongation of the shockwave in rapidity due to the longitudinal expansion of the bulk medium. Using a single hadron trigger, this cannot be observed due to the unconstrained rapidity of the away side parton. Using a dihadron trigger, the rapidity of the away side parton can be substantially constrained and the longitudinal structure of the away side correlation becomes accessible. However, in such events several effects occur which change the correlation structure substantially: There is not only a sizeable contribution due to the fragmentation of the emerging away side parton, but also a systematic bias towards small energy deposition into the medium and hence a weak shockwave. In this paper, both effects are addressed.Comment: 5 pages, 2 figure

Evangelical Visitor - February 01, 1943 Vol. LVI. No. 3.

Vol. LVI. No. 3

Evangelical Visitor - April 12, 1943 Vol. LVI. No. 8.

Vol. LVI. No. 8

Evangelical Visitor - March 01, 1943 Vol. LVI. No. 5.

Vol. LVI. No. 5