Comparison of model predictions for elliptic flow with experiment for Pb+Pb collisions at sqrt{sNN}=2.76 TeV

A simple kinematic model based on the superposition of p+p collisions, relativistic geometry and hadronic rescattering is used to predict the elliptic flow observable in sqrt{sNN} = 2.76 TeV Pb+Pb collisions. A short proper time for hadronization is assumed. The predictions are compared with recent experimental measurements of elliptic flow which have been made for this colliding system and energy. It is found that the model predictions do a reasonable job in describing the experimental results, suggesting that the parton phase in these collisions may be short-lived.Comment: 4 pages, 2 figures, submitted to Physical Review, typo corrected, discussion augmente

Hadronic observables from Au+Au collisions at s(NN)**(1/2)=200 GeV and Pb+Pb collisions at s(NN)**(1/2)=5.5 TeV from a simple kinematic model

A simple kinematic model based on superposition of p+p collisions, relativistic geometry and final-state hadronic rescattering is used to calculate various hadronic observables in s(NN)**(1/2) = 200 GeV Au+Au collisions and s(NN)**(1/2) = 5.5 TeV Pb+Pb collisions. The model calculations are compared with experimental results from several s(NN)**(1/2) = 200 GeV Au+Au collision studies. If a short hadronization time is assumed in the model, it is found that this model describes the trends of the observables from these experiments surprisingly well considering the model's simplicity. This also gives more credibility to the model predictions presented for s(NN)**(1/2) = 5.5 TeV Pb+Pb collisions.Comment: 32 pages, 21 figures, figure and text added for version of paper published in Physical Review

Signatures for Black Hole production from hadronic observables at the Large Hadron Collider

The concept of Large Extra Dimensions (LED) provides a way of solving the Hierarchy Problem which concerns the weakness of gravity compared with the strong and electro-weak forces. A consequence of LED is that miniature Black Holes (mini-BHs) may be produced at the Large Hadron Collider in p+p collisions. The present work uses the CHARYBDIS mini-BH generator code to simulate the hadronic signal which might be expected in a mid-rapidity particle tracking detector from the decay of these exotic objects if indeed they are produced. An estimate is also given for Pb+Pb collisions.Comment: 11 pages, 9 figures, ISHIP 2006 conference proceedin

Mini black holes at the LHC : discovery through di-jet suppression, mono-jet emission and a supersonic boom in the quark-gluon plasma in ALICE, ATLAS and CMS

We examine experimental signatures of TeV-mass black hole formation in heavy ion collisions at the LHC. We find that the black hole production results in a complete disappearance of all very high p_T (> 500 GeV) back-to-back correlated di-jets of total mass M > M_f ~ 1 TeV. We show that the subsequent Hawking-decay produces multiple hard mono-jets and discuss their detection. We study the possibility of cold black hole remnant (BHR) formation of mass ~ M_f and the experimental distinguishability of scenarios with BHRs and those with complete black hole decay. Finally we point out that a Heckler-Kapusta-Hawking plasma may form from the emitted mono-jets. In this context we present new simulation data of Mach shocks and of the evolution of initial conditions until the freeze-out

Can hadronic rescattering explain the "jet quenching" at RHIC?

Recent RHIC data have shown novel nuclear modifications of moderate to high pt particle production in central Au+Au collisions, including a suppression of hadron production and a disappearance of back-to-back hadron pairs. In this paper, we investigate whether final-state hadronic interactions of the jet fragments can reproduce the RHIC data. We find that hadronic rescattering can account for the disappearance of back-to-back hadron pairs, but cannot reproduce other features of the RHIC data.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

Femtoscopic signatures of collective behavior as a probe of the thermal nature of relativistic heavy ion collisions

Femtoscopy measures space-time characteristics of the particle emitting source created in relativistic heavy-ion collisions. It is argued that collective behavior of matter (radial flow) produces specific femtoscopic signatures. The one that is best known, the m_T dependence of the pion ``HBT radii'', can be explained by the alternative scenario of temperature gradients in an initial state thermal model. We identify others that can invalidate such alternatives, such as non-identical particle correlations and m_T scaling for particles of higher mass. Studies with a simple rescattering code show that as the interaction cross-section is increased the system develops collective behavior and becomes more thermalized at the same time, the two effects being the natural consequence of increased number of particle rescatterings. Repeating calculations with a more realistic rescattering model confirmed all of these conclusions and provided deeper insight into the mechanisms of collectivity buildup, showing a preference for a thermal model with uniform temperature.Comment: 9 pages, 11 figures ver2: added CERN report no., added references to relevant previous works on transport model

Partonic flow and ϕ\phi-meson production in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

We present first measurements of the $\phi$-meson elliptic flow ($v_{2}(p_{T})$) and high statistics $p_{T}$ distributions for different centralities from $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions at RHIC. In minimum bias collisions the $v_{2}$ of the $\phi$ meson is consistent with the trend observed for mesons. The ratio of the yields of the $\Omega$ to those of the $\phi$ as a function of transverse momentum is consistent with a model based on the recombination of thermal $s$ quarks up to $p_{T}\sim 4$ GeV/$c$, but disagrees at higher momenta. The nuclear modification factor ($R_{CP}$) of $\phi$ follows the trend observed in the $K^{0}_{S}$ mesons rather than in $\Lambda$ baryons, supporting baryon-meson scaling. Since $\phi$-mesons are made via coalescence of seemingly thermalized $s$ quarks in central Au+Au collisions, the observations imply hot and dense matter with partonic collectivity has been formed at RHIC.Comment: 6 pages, 4 figures, submit to PR

Studies of di-jet survival and surface emission bias in Au+Au collisions via angular correlations with respect to back-to-back leading hadrons

We report first results from an analysis based on a new multi-hadron correlation technique, exploring jet-medium interactions and di-jet surface emission bias at RHIC. Pairs of back-to-back high transverse momentum hadrons are used for triggers to study associated hadron distributions. In contrast with two- and three-particle correlations with a single trigger with similar kinematic selections, the associated hadron distribution of both trigger sides reveals no modification in either relative pseudo-rapidity or relative azimuthal angle from d+Au to central Au+Au collisions. We determine associated hadron yields and spectra as well as production rates for such correlated back-to-back triggers to gain additional insights on medium properties.Comment: By the STAR Collaboration. 6 pages, 2 figure