2,913 research outputs found
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
Charm-quark fragmentation with an effective coupling constant
We use a recently proposed non-perturbative model, based on an effective
strong coupling constant and free from tunable parameters, to study c-flavoured
hadron production in e+e- annihilation. Charm-quark production is described in
the framework of perturbative fragmentation functions, with NLO coefficient
functions, NLL non-singlet DGLAP evolution and NNLL large-x resummation. We
model hadronization effects by means of the effective coupling constant in the
NNLO approximation and compare our results with experimental data taken at the
Z0 pole and at the Upsilon(4S) resonance. We find that, within the experimental
and theoretical uncertainties, our model is able to give a reasonable
description of D*+-meson spectra from ALEPH for x<1-Lambda/m_c. More serious
discrepancies are instead present when comparing with D and D^* data from BELLE
and CLEO in x-space. Within the errors, our model is nonetheless capable of
reproducing the first ten Mellin moments of all considered data sets. However,
the fairly large theoretical uncertainties call for a full NNLO/NNLL analysis.Comment: 26 pages, 10 figures. Analysis in Mellin space and few references
adde
Measurement of Heavy Quark cross-sections at CDF
The measurement of heavy quark cross-sections provides important tests of the
QCD theory. This paper reviews recent measurements of single b-quark and
correlated b-quark cross-sections at CDF. Two new measurements of the single
b-quark production at CDF agree with the first result from CDF Run II. This
clarifies the experimental situation and confirms the recent agreement of
theoretical prediction with data. A new measurement of the correlated
cross-section with dimuon events at CDF is presented. It agrees with
theory and it does not confirm the anomalously large cross-section
seen in Run I by CDF and D in dimuon events.Comment: EPS HEP2007 conference held in Mancheste
Jets in 200 GeV p+p and d+Au collisions from the STAR experiment at RHIC
Full jet reconstruction in heavy-ion collisions is a promising tool for the
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 kT broadening and jet quenching. Study of
jet production and properties in d+Au in combination with similar studies in
p+p is an important baseline measurement needed to better understand heavy-ion
results. We present mid-rapidity inclusive jet pT spectra and di-jet
correlations (kT) in 200 GeV p+p and d+Au collisions from the 2007-2008 RHIC
run. We discuss the methods used to correct the data for detector effects and
for background in d+Au collisions.Comment: 4 pages, 5 figures. To appear in Hot Quarks 2010 conference
proceeding
Measurements of the top-antitop production cross section at the Tevatron Run II CDF experiment using b-tagging
We present measurements of the top-antitop production cross section in
b-tagged lepton + jets events from proton-antiproton collisions at 1.96 TeV
using the CDF detector at Fermilab. B-jets are tagged with either a secondary
vertex algorithm, or a soft lepton tagger that identifies muons from B hadron
semileptonic decays. With Tevatron Run II data, we estimate the top-antitop
signal fraction in two different ways: by estimating the various background
contributions, and by fitting directly the leading jet transverse energy
spectrum for the signal and background contributions. A subset of the sample
with two secondary vertex tagged jets yields a production cross section
consistent with the inclusive measurements. Results are consistent with a
Standard Model top-antitop signal and current measurements of the top quark
mass.Comment: 3 pages, 4 figures, DPF 2004 proceedin
Phenomenological study of charm photoproduction at HERA
We present predictions for single inclusive distributions of charmed mesons,
relevant to the HERA experiments. Our results are based upon a computation that
correctly incorporates mass effects up to the next-to-leading order level, and
the resummation of transverse momentum logarithms up to
next-to-leading-logarithmic level. We apply the same acceptance cuts as the H1
and Zeus experiments, and compare our results to their data. We perform a study
of the sensitivity of our predictions on the charm mass, \LambdaQCD,
factorization scale, renormalization scale, and fragmentation parameters.Comment: 15 pages Latex; 25 figures include
Optimal jet radius in kinematic dijet reconstruction
Obtaining a good momentum reconstruction of a jet is a compromise between
taking it large enough to catch the perturbative final-state radiation and
small enough to avoid too much contamination from the underlying event and
initial-state radiation. In this paper, we compute analytically the optimal jet
radius for dijet reconstructions and study its scale dependence. We also
compare our results with previous Monte-Carlo studies.Comment: 30 pages, 11 figures; minor corrections; published in JHE
Mixings, Lifetimes, Spectroscopy and Production of Heavy Flavor at the Tevatron
The Fermilab Tevatron offers unique opportunities to perform measurements of
the heavier B hadrons that are not accessible at the Upsilon(4S) resonance. In
this summary, we describe some recent heavy flavor results from the DO and CDF
collaborations and discuss prospects for future measurements.Comment: To appear in Proceedings of the XXI International Symposium on lepton
and Photon Interactions at High Energies, Fermilab, August 200
The \pt spectrum of heavy quarks in photoproduction
We illustrate a formalism that allows to match the next-to-leading order
cross section for the photoproduction of heavy quarks to the cross section
obtained by resumming logarithms of \pt/m to the next-to-leading accuracy,
thus giving a sensible prediction for any value of \pt. We present a
comparison between our predictions and H1 and ZEUS data.Comment: 4 pages Latex; 3 figures included. Talk given at DIS01, 27 April - 1
May 2001, Bologna, Ital
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