How robust is a thermal photon interpretation of the ALICE low-p_T data?
arXiv:1307.7034 · doi:10.1007/JHEP10(2013)119
Abstract
We present a rigorous theoretical analysis of the ALICE measurement of low-p_T direct-photon production in central lead-lead collisions at the LHC with a centre-of-mass energy of \sqrt{s_{NN}}=2.76 TeV. Using NLO QCD, we compute the relative contributions to prompt-photon production from different initial and final states and the theoretical uncertainties coming from independent variations of the renormalisation and factorisation scales, the nuclear parton densities and the fragmentation functions. Based on different fits to the unsubtracted and prompt-photon subtracted ALICE data, we consistently find T = 304 \pm 58 MeV and 309 \pm 64 MeV for the effective temperature of the quark-gluon plasma (or hot medium) at p_T \in [0.8;2.2] GeV and p_T \in [1.5;3.5] GeV as well as a power-law (p_T^{-4}) behavior for p_T > 4 GeV as predicted by QCD hard scattering.
arXiv comment18 pages, 7 figures, 1 table
References in corpus (42)
- Parton distributions for the LHC
- New Generation of Parton Distributions with Uncertainties from Global QCD Analysis
- EPS09 - a New Generation of NLO and LO Nuclear Parton Distribution Functions
- Inclusive Jet Production, Parton Distributions, and the Search for New Physics
- Enhanced production of direct photons in Au+Au collisions at sqrt(s_NN)=200 GeV and implications for the initial temperature
- Tevatron Run-1 Z Boson Data and Collins-Soper-Sterman Resummation Formalism
- Determination of nuclear parton distribution functions and their uncertainties at next-to-leading order
- Evolution of the nuclear modification factors with rapidity and centrality in d+Au collisions at $\sqrt{s_{NN}} = 200 GeV
- Global Analysis of Nuclear Parton Distributions
- Centrality Dependence of Direct Photon Production in sqrt(s_NN) = 200 GeV Au+Au Collisions
- A new critical study of photon production in hadronic collisions
- Transverse momentum distribution and nuclear modification factor of charged particles in p-Pb collisions at = 5.02 TeV
- Measurement of the Inclusive Upsilon production cross section in pp collisions at sqrt(s)=7 TeV
- Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV
- Measurement of Direct Photons in pp and Pb-Pb Collisions with ALICE
- Thermal photons as a quark-gluon plasma thermometer revisited
- PDF Nuclear Corrections for Charged Lepton and Neutrino Deep Inelastic Scattering Processes
- Higher-Order QCD Corrections in Prompt Photon Production
- Theory of hard photoproduction
- Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data
- Measurement of the Differential Cross Section for Isolated Prompt Photon Production in pp Collisions at 7 TeV
- Measurement of the Isolated Prompt Photon Production Cross Section in pp Collisions at sqrt(s) = 7 TeV
- Elliptic flow of thermal photons from event-by-event hydrodynamic model
- Hard pion and prompt photon at RHIC, from single to double inclusive production
- Induced photon emission from quark jets in ultrarelativistic heavy-ion collisions
- Probing the QCD equation of state with thermal photons in nucleus-nucleus collisions at RHIC
- Enhancement of thermal photon production in event-by-event hydrodynamics
- Massive Lepton Pairs as a Prompt Photon Surrogate
- Distorting the Hump-backed Plateau of Jets with Dense QCD Matter
- Hard scattering cross sections at LHC in the Glauber approach: from pp to pA and AA collisions
- Probing Nuclear Matter with Jet Conversions
- Strong Coupling Constant from the Photon Structure Function
- Large Transverse Momentum Jet Production and DIS Distributions of the Proton
- Centrality dependence of inclusive prompt photon production in d+Au, Au+Au, p+Pb, and Pb+Pb collisions
- Nuclear Broadening Effects on Hard Prompt Photons at Relativistic Energies
- Recoil and Power Corrections in High-x_T Direct-Photon Production
- Meson spectra and m_T scaling in p+p, d+Au and Au+Au collisions at \sqrtS_NN=200 GeV
- Nuclear Shadowing Effects on Prompt Photons at RHIC and LHC
- Spin Dependence of Massive Lepton Pair Production in Proton-Proton Collisions
- Parton densities from LHC vector boson production at small and large transverse momenta
- Medium-modified DGLAP evolution of fragmentation functions from large to small x
- Transverse Resummation for Direct Photon Production
Cited by in corpus (18)
- QCD and strongly coupled gauge theories: challenges and perspectives
- The production of photons in relativistic heavy-ion collisions
- Direct photon production in Pb-Pb collisions at $\sqrt{s_\rm{NN}}$ = 2.76 TeV
- Heavy quarks and jets as probes of the QGP
- Thermal photons as a quark-gluon plasma thermometer revisited
- Collectivity and electromagnetic radiation in small systems
- Production and Elliptic Flow of Dileptons and Photons in the semi-Quark Gluon Plasma
- Heavy-ion collisions at the Large Hadron Collider: a review of the results from Run 1
- An overview of experimental results from ultra-relativistic heavy-ion collisions at the CERN LHC: bulk properties and dynamical evolution
- Probing the small- nuclear gluon distributions with isolated photons at forward rapidities in p+Pb collisions at the LHC
- Nuclear PDFs in the beginning of the LHC era
- A perturbative QCD study of dijets in p+Pb collisions at the LHC
- Photon from the annihilation process with CGC in the collision
- Prompt photon production and photon-jet correlations at the LHC
- Nuclear parton density modifications from low-mass lepton pair production at the LHC
- Radiative hadronization: Photon emission at hadronization from quark-gluon plasma
- Impact of scale, nuclear PDF and temperature variations on the interpretation of medium-modified jet production data from the LHC
- Parton density constraints from massive vector boson production at the LHC