2,237 research outputs found
Jet Fragmentation in Vacuum and Medium with gamma-hadron Correlations in PHENIX
Jet fragmentation in p+p and Au+Au collisions is studied via back-to-back
correlations of direct photons and charged hadrons. The direct photon
correlations are obtained by statical subtraction of the background from decay
photons. Results on the nuclear modification to the associated charged hadron
yields are reviewed. Further studies of jet fragmentation in p+p using isolated
direct photons are also presented. A kT-smeared LO pQCD calculation is used to
interpret the data. The sensitivity of the data to the underlying fragmentation
function is tested and the results are found to be compatible with expectations
of a sample dominated by quark jet fragmentation.Comment: Talk presented at Hot Quarks 2010, June 21-26, La Londe Les Maures,
France. To be published in Journal of Physics: Conference Series (JPCS
INFN What Next: Ultra-relativistic Heavy-Ion Collisions
This document was prepared by the community that is active in Italy, within
INFN (Istituto Nazionale di Fisica Nucleare), in the field of
ultra-relativistic heavy-ion collisions. The experimental study of the phase
diagram of strongly-interacting matter and of the Quark-Gluon Plasma (QGP)
deconfined state will proceed, in the next 10-15 years, along two directions:
the high-energy regime at RHIC and at the LHC, and the low-energy regime at
FAIR, NICA, SPS and RHIC. The Italian community is strongly involved in the
present and future programme of the ALICE experiment, the upgrade of which will
open, in the 2020s, a new phase of high-precision characterisation of the QGP
properties at the LHC. As a complement of this main activity, there is a
growing interest in a possible future experiment at the SPS, which would target
the search for the onset of deconfinement using dimuon measurements. On a
longer timescale, the community looks with interest at the ongoing studies and
discussions on a possible fixed-target programme using the LHC ion beams and on
the Future Circular Collider.Comment: 99 pages, 56 figure
Jet-Medium Interactions with Identified Particles
Identified particles have long been of great interest at RHIC in large part
because of the baryon/meson differences observed at intermediate and the
implications for hadronization via quark coalescence. With recent high
statistics data identified particles are also now central to understanding the
details of the jet-medium interactions and energy loss and hadron formation at
intermediate and high . In particular, high identified particle
spectra along with two-particle correlations triggered with direct photons,
neutral pions or electrons from heavy flavor decay with hadrons can provide
information about how medium modifications to jet fragmentation depend on
parton type. I will review recent results with identified particles both in
heavy ion systems and the reference measurements in p+p collisions.Comment: Proceedings for Quark Matter 2009, Knoxville T
Progress in jet reconstruction and heavy ion collisions
We review recent developments related to jet clustering algorithms and jet
reconstruction, with particular emphasis on their implications in heavy ion
collisions. These developments include fast implementations of sequential
recombination algorithms, new IRC safe algorithms, quantitative determination
of jet areas and quality measures for jet finding, among many others. We also
show how jet reconstruction provides a useful tool to probe the characteristics
of the hot and dense medium created in heavy ion collisions, which allows one
to distinguish between different models of parton-medium interaction.Comment: 7 pages, 4 figures, to appear in the proceedings of the 13th
International Conference on Elastic & Diffractive Scattering, CERN, 29th June
- 3rd July 200
Medium modification of jet fragmentation in Au+Au collisions at sqrt(s_NN)=200 GeV measured in direct photon-hadron correlations
The jet fragmentation function is measured with direct photon-hadron
correlations in p+p and Au+Au collisions at sqrt(s_NN)=200 GeV. The p_T of the
photon is an excellent approximation to the initial p_T of the jet and the
ratio z_T=p_T^h/p_T^\gamma is used as a proxy for the jet fragmentation
function. A statistical subtraction is used to extract the direct photon-hadron
yields in Au+Au collisions while a photon isolation cut is applied in p+p. I_
AA, the ratio of jet fragment yield in Au+Au to that in p+p, indicates
modification of the jet fragmentation function. Suppression, most likely due to
energy loss in the medium, is seen at high z_T. The fragment yield at low z_T
is enhanced at large angles. Such a trend is expected from redistribution of
the lost energy into increased production of low-momentum particles.Comment: 562 authors, 70 insitutions, 8 pages, and 3 figures. Submitted to
Phys. Rev. Lett. v2 has minor changes to improve clarity. Plain text data
tables for the points plotted in figures for this and previous PHENIX
publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Photon and neutral pion production in pp and Pb-Pb collisions at LHC energies in the ALICE experiment
We present the results for direct photon and neutral pion production obtained
from proton-proton and lead-lead collisions in the ALICE experiment.
Measurement of neutral pions in pp collisions allows to test the validity of
QCD-inspired models. The study of neutral pion yields in Pb-Pb collisions
permits to study the medium-induced suppression relative to the pp case. The
yield of direct photons is compared to perturbative QCD calculations. In the
case of central Pb-Pb collisions the observed excess of photons below 4 GeV/c
is used to find the effective temperature of the matter.Comment: Talk presented at LISHEP 2015, 14 pages, 15 figure
Jet-hadron correlations relative to the event plane at the LHC with ALICE
The hot, dense and strongly interacting medium known as the Quark Gluon
Plasma (QGP) is produced in relativistic heavy-ion collisions at the Large
Hadron Collider (LHC). Early in the collisions, quarks and gluons from the
incoming nuclei collide to produce high momentum partons which fragment into
collimated sprays of hadrons called "jets". In pp collisions, jet production is
well understood within the framework of perturbative QCD and acts as a rigorous
baseline measurement for jet quenching measurements. Using pp as a reference,
we can compare to heavy-ion collision systems, and study the modification of
the or angular distributions of jet fragments. A recently developed
background subtraction method to remove the complex, flow dominated, heavy-ion
background will be used in this analysis. Azimuthal angular correlations of
charged hadrons with respect to the axis of a full (charged + neutral)
reconstructed 'trigger' jet in Pb--Pb collisions at TeV in
ALICE will be presented here. The analysis of angular correlations for
different orientations of the trigger relative to the event plane allows for
the study of the path length dependence of medium modifications to jets. The
status of studies of the event plane dependence of angular correlations will be
presented.Comment: 4 pages, 4 figures, Hot Quarks 2016 conferenc
Jet Quenching at LHC
We review up-to-date results on high-pt particles and jets in heavy ion
collisions by three major LHC experiments, ALICE, ATLAS, and CMS. Results of
analyses of 2010 and 2011 Pb+Pb data at TeV are
discussed. We concentrate mainly on results by fully reconstructed jets and
discuss similarities and important differences in measurements among
experiments. We point to the importance of understanding the results in a view
of difference between quark-initiated and gluon-initiated jetsComment: Review prepared for MPL
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