5,119 research outputs found
Initial state nuclear effects for jet production measured in d+Au collisions by STAR
Full jet reconstruction in heavy-ion collisions is a promising tool for
quantitative study of properties of the dense medium produced at RHIC.
Measurements of d+Au collisions are important to disentangle initial state
nuclear effects from medium-induced broadening and jet
quenching. We report measurements of mid-rapidity ()
di-jet correlations in d+Au using high-statistics run 8 RHIC data at
.Comment: 2 pages, 2 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse
Exploring Jet Properties in p-p Collisions at 200 GeV with STAR
The mechanisms underlying hadronization are not well understood, both in
vacuum and in hot QCD matter. Precise characterization of jet fragmentation to
hadrons in p-p collisions will help elucidate the fundamental process of
hadronization, and will serve as essential reference to measure the
modification of hadronization in heavy ion collisions. We present measurements
of fragmentation functions for unidentified particles in jets produced in p-p
collisions at 200 GeV using the STAR detector at RHIC. The results from
different jet reconstruction algorithms are compared, including variations of
the resolution parameter. It is found that the results are largely insensitive
to details of the jet-finding algorithm at RHIC energies. Particle production
inside and outside of these reconstructed jets will be compared to improve our
understanding of the hadronization mechanisms for soft and hard particles in
p-p events at RHIC energies.Comment: 4 pages, 7 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee Final version
after referee's comment
Measurement of jet spectra in Pb-Pb collisions at =2.76 TeV with the ALICE detector at the LHC
We report a measurement of transverse momentum spectra of jets detected with
the ALICE detector in Pb-Pb collisions at sqrt(sNN)=2.76 TeV. Jets are
reconstructed from charged particles using the anti-kt jet algorithm. The
background from soft particle production is determined for each event and
subtracted. The remaining influence of underlying event fluctuations is
quantified by embedding different probes into heavy-ion data. The reconstructed
transverse momentum spectrum is corrected for background fluctuations by
unfolding. We compare the inclusive jet spectra reconstructed with R=0.2 and
R=0.3 for different centrality classes and compare the jet yield in Pb-Pb and
pp events.Comment: * Temporary entry *; 4 pages, 7 figures, proceedings from 5th
International Conference on Hard and Electromagnetic Probes of High-Energy
Nuclear Collisions (Hard Probes 2012) at Cagliari (Italia
Heavy Quarks: Lessons Learned from HERA and Tevatron
We review some of the recent developments which have enabled the heavy quark
mass to be incorporated into both the calculation of the hard-scattering cross
section and the PDFs. We compare and contrast some of the schemes that have
been used in recent global PDF analyses, and look at issues that arise when
these calculations are extended to NNLO.Comment: 11 pages, 9 figures, to appear in the proceedings of the Ringberg
Workshop "New Trends in HERA Physics 2008
Collinear Subtractions in Hadroproduction of Heavy Quarks
We present a detailed discussion of the collinear subtraction terms needed to
establish a massive variable-flavour-number scheme for the one-particle
inclusive production of heavy quarks in hadronic collisions. The subtraction
terms are computed by convoluting appropriate partonic cross sections with
perturbative parton distribution and fragmentation functions relying on the
method of mass factorization. We find (with one minor exception) complete
agreement with the subtraction terms obtained in a previous publication by
comparing the zero-mass limit of a fixed-order calculation with the genuine
massles results in the MSbar scheme. This presentation will be useful for
extending the massive variable-flavour-number scheme to other processes.Comment: 29 pages, 17 figures include
Measurement of charged jet cross sections and jet shapes in proton-proton collisions at sqrt(s) = 2.76 TeV with the ALICE detector at LHC
We present measurements of charged jet cross sections and jet shape
observables in leading jet in proton-proton (pp) collisions at sqrt(s) = 2.76
TeV with the ALICE detector at LHC. Jets are reconstructed at the midrapidity
from charged particle using sequential recombination anti-kT jet finding
algorithm for various R values. The results are compared to measurements from
HERWIG, PHOJET and different tunes of PYTHIA6 and earlier measurements at 7
TeV.Comment: Proceedings of XXII DAE-BRNS High Energy Physics Symposium 2016
conference, 12-16 December, 201
Perturbative and Non-Perturbative Issues in Heavy Quark Fragmentation
We review the state-of-the-art of our understanding of heavy quark
fragmentation. Recent e^+e^- data for B mesons are compared to the most
up-to-date theoretical predictions, and the need for inclusion of a
non-perturbative component is discussed. Experimental analyses in moments space
are suggested, and it is pointed out how perturbative and non-perturbative
contributions are to be properly matched. Failure to do so can result in large
phenomenological discrepancies. An example is given for B^+ hadroproduction at
the Tevatron.Comment: 6 pages, LaTeX2e, Talk given at the 37th Rencontres de Moriond on QCD
and Hadronic Interactions, Les Arcs, France, 16-23 March 2002. To be
published in the Proceeding
QCD Predictions for Charm and Bottom Production at RHIC
We present up-to-date QCD predictions for open charm and bottom production at
RHIC in nucleon-nucleon collisions at \sqrt{S} = 200 GeV. The electron spectrum
resulting from heavy flavor decays is also evaluated for direct comparison to
the PHENIX and STAR data. These predictions seek to establish a rigorous
benchmark, including the theoretical uncertainties, against which nuclear
collision data can be compared to obtain evidence for nuclear effects.Comment: 4 pages, to appear in the proceedings of the International
Europhysics Conference on High Energy Physics, 21-27 July 2005, Lisbon,
Portuga
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