RHIC-tested predictions for low-p(TT) and high-p(TT) hadron spectra in nearly central Pb + Pb collisions at the CERN LHC

Jun, 2005
46 pages
Published in:
  • Phys.Rev.C 72 (2005) 044904
e-Print:
Report number:
  • HIP-2005-24-TH

Citations per year

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Abstract:
We study the hadron spectra in nearly central AA+AA collisions at RHIC and LHC in a broad transverse momentum range. We cover the low-pTp_T spectra using longitudinally boost-invariant hydrodynamics with initial energy and net-baryon number densities from the perturbative QCD (pQCD)+saturation model. Build-up of the transverse flow and sensitivity of the spectra to a single decoupling temperature \Tdec are studied. Comparison with RHIC data at \ssNN=130 and 200 GeV suggests a rather high value \Tdec=150 MeV. The high-pTp_T spectra are computed using factorized pQCD cross sections, nuclear parton distributions, fragmentation functions, and describing partonic energy loss in the quark-gluon plasma by quenching weights. Overall normalization is fixed on the basis of p+pˉ\bar{\rm p}(p) data and the strength of energy loss is determined from RHIC Au+Au data. Uncertainties are discussed. With constraints from RHIC data, we predict the pTp_T spectra of hadrons in 5 % most central Pb+Pb collisions at the LHC energy \ssNN=5500 GeV. Due to the closed framework for primary production, we can also predict the net-baryon number at midrapidity, as well as the strength of partonic energy losses at the LHC. Both at the LHC and RHIC, we recognize a rather narrow crossover region in the pTp_T spectra, where the hydrodynamic and pQCD fragmentation components become of equal size. We argue that in this crossover region the two contributions are to a good approximation mutually independent. In particular, our results suggest a wider pTp_T-region of applicability for hydrodynamical models at the LHC than at RHIC.
  • 24.85.+p
  • 25.75.Nq
  • 12.38.Bx
  • 24.10.NZ
  • scattering: heavy ion
  • lead
  • gold
  • hadron: multiple production
  • central region
  • transverse momentum: spectrum
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