Energy Loss of Leading Partons in a Thermal QCD Medium

Abstract

We consider bremsstrahlung energy loss for hard partons traversing a quark-gluon plasma. Accounting correctly for the probabilistic nature of the energy loss, and making a leading-order accurate treatment of bremsstrahlung, we find that the suppression of the spectrum is nearly flat, with the most suppression at energies $E \sim 30 T$ ($T$ the QGP temperature), in contrast to previous literature but in agreement with experimental data. This flat pattern should also be observed at the LHC.

Figures (3)

• Figure 1: Time evolution of an initially monoenergetic ensemble of quarks. For comparison, vertical bars show the energy of the quarks if we take the energy loss to be a steady process, determined by Eq. (\ref{['eq:dEdt']}).
• Figure 2: The ratios of the final and the initial momentum spectra for quarks. The black and red (solid) curves are calculated by solving Eq.(\ref{['eq:Fokker']}) directly. The blue and green (dashed) curves are calculated by first calculating $dE/dt$.
• Figure 3: The ratios of the final and the initial momentum spectra for quarks. The solid curves are calculated by solving Eq.(\ref{['eq:Fokker']}) directly. The dashed curves are calculated by first calculating $dE/dt$. The evolution time is $2/T$. The integer $n$ corresponds to having initial spectrum $f_0 \propto 1/(p_0^2 + p^2)^n$.