Pion quenching and tomography from RHIC to LHC in the WHDG model

May 26, 2011, 3:40 PM
Salle de l'Europe (Centre Bonlieu)

Salle de l'Europe

Centre Bonlieu

Parallel Jets Jets


William Horowitz (University of Cape Town)


We present parameter-free predictions from the WHDG (radiative+elastic+geometric fluctuation) energy loss model for high pT pion suppression in A+A at 2.76 and 5.5 ATeV. The input density is constrained from a rigorous statistical analysis of RHIC pi0 quenching data. The predictions are consistent with the recent _charged_ hadron RAA data from ALICE only within the current very large systematic uncertainty (due to the unmeasured reference p + p spectrum). However, our constrained prediction of central to peripheral pion R_cp(pT), in which reference p + p spectra uncertainties cancel, is found to be over-quenched by ~two sigma relative to the charged hadron ALICE R_cp data at all pT<20 GeV. The basic tomographic assumptions in WHDG are (1) the energy loss scales linearly with the initial QGP density, rho0, and (2) that rho0 scales linearly with charge particle multiplicity dNch/dy. Under these assumptions, WHDG predicts significant difference in magnitude and pt slope pf pion RAA between RHIC and LHC. Future ALICE identified pi,K,p hadron RAA data (as well as accurate p + p and p + Pb reference data) will enable more quantitative jet tomographic tests of hard probe dynamics in strongly interacting quark gluon plasmas.

Primary author

Miklos Gyulassy (Columbia University)


Prof. William Horowitz (University Cape Town)

Presentation materials