Examining a reduced jet-medium coupling in Pb+Pb collisions at the Large Hadron Collider

2012/01/31 by Barbara Betz, Miklos Gyulassy, Miklós Gyulassy · 53 citations
Physics and Astronomy · #Coupling (piping) #Elliptic flow #Energy (signal processing) #Hadron #High-Energy Particle Collisions Research #Jet (fluid) #Large Hadron Collider #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Quark–gluon plasma #Range (aeronautics) #Thermodynamics #hep-ph #nucl-ex #nucl-th

paper · pdf · doi:10.1103/physrevc.86.024903

published in Physical Review C 86(2) (American Institute of Physics) · 10 pages, 7 figures, version published in Physical Review C

openalex publication_date 2012/08/06 · arxiv created 2012/08/07 · arxiv updated 2013/05/29 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

Recent data on the nuclear modification factor R_AA of jet fragments in 2.76 ATeV Pb+Pb collisions at the Large Hadron Collider (LHC) indicate that the jet-medium coupling in a quark-gluon plasma (QGP) is reduced at LHC energies and not compatible with the coupling deduced from data at the Relativistic Hadron Collider (RHIC). We estimate the reduction factor from a combined fit to the available data on R_AA(√(s),p_T,b) and the elliptic flow v₂(√(s),p_T,b) at √(s)=0.2,2.76 ATeV over a transverse momentum range p_T\ensuremath∼10--100 GeV and a broad impact parameter, b, range. We use a simple analytic ``polytrope'' model (dE/dx=\ensuremath-\ensuremathκE^ax^zT^c) to investigate the dynamical jet-energy loss model dependence. Varying a=0--1 interpolates between weakly coupled and strongly coupled models of jet-energy dependence while z=0--2 covers a wide range of possible jet-path dependencies from elastic and radiative to holographic string mechanisms. Our fit to LHC data indicates an approximate 40% reduction of the coupling \ensuremathκ from RHIC to LHC and excludes energy-loss models characterized by a jet-energy exponent with a>1/3. In particular, the rapid rise of R_AA with p_T\ensuremath≥10 GeV combined with the slow variation of the asymptotic v₂(p_T) at the LHC rules out popular exponential geometric optics models (a=1). The LHC data are compatible with 0\ensuremath≤a\ensuremath≤1/3 pQCD-like energy-loss models where the jet-medium coupling is reduced by approximately 10% between RHIC and LHC.

Citations

• Fourier harmonics of high-pTparticles probing the fluctuating initial condition geometries in heavy-ion collisions
• Medium-induced jet absorption in relativistic heavy-ion collisions
• Manifestations of high density QCD in the first RHIC data
• Heavy-flavour production in Pb–Pb collisions at the LHC, measured with the ALICE detector
• New forms of QCD matter discovered at RHIC
• Experimental and theoretical challenges in the search for the quark–gluon plasma: The STAR Collaboration's critical assessment of the evidence from RHIC collisions
• The large N limit of superconformal field theories and supergravity

Cited by

• OBSERVATION OF A RIDGE CORRELATION STRUCTURE IN HIGH MULTIPLICITY PROTON–PROTON COLLISIONS: A BRIEF REVIEW
• Jet modifications in event-by-event hydrodynamically evolving media
• Quantifying a Possibly Reduced Jet-Medium Coupling of the sQGP at the LHC
• Azimuthal jet tomography at RHIC and LHC
• Single top quark production in heavy ion collisions at energies available at the CERN Large Hadron Collider