5,515 research outputs found
Quarkonia production with the Hera-B experiment
Measurements of the dependence of the J/Psi production cross section on its
kinematic variables as well as on the target atomic numbers for 920 GeV/c
protons incident on different targets have been made with the Hera-B detector.
The large collected di-lepton sample allows to study the production ratio of
Psi(2S) to J/Psi and of Chic to J/Psi . We also report on measurements of the
b-bbar and Upsilon production cross section.Comment: 9 pages, 11 figure
Cold nuclear effects on heavy flavours (a review)
Before wondering about the quark-gluon plasma (QGP), one has to take into
account various cold (normal) nuclear matter effects, that can be probed
through p+A like collisions. This article aims at reviewing the current results
(and understanding) of these effects on heavy quarks and quarkonia production.Comment: 8 pages, 6x2 figures, SQM08 proceedings, version accepted by
J.Phys.G. Figure 4 left and 5 right remad
Measurement of J/Psi production in pp collisions at sqrt(s)=2.76 and 7 TeV with ALICE
We present results from the ALICE experiment on the inclusive J/Psi
production in pp collisions at sqrt(s)=2.76 and 7 TeV. The integrated and
differential cross sections are evaluated down to pT=0 in two rapidity ranges,
|y|<0.9 and 2.5<y<4, in the dielectron and dimuon decay channel respectively.
The measurement at sqrt(s)=2.76 TeV, the same energy as Pb-Pb collisions,
provides a crucial reference for the study of hot nuclear matter effects on
J/Psi production. The J/Psi yield in pp collisions at sqrt(s)=7 TeV has also
been studied as a function of the charged particle multiplicity and first
results are presented.Comment: 4 pages, 4 figures, parallel talk at Quark Matter 2011, Annecy,
Franc
Heavy Flavor Probes of Quark Matter
A brief survey of the role of heavy flavors as a probe of the state of matter
produced by high energy heavy ion collisions is presented. Specific examples
include energy loss, initial state gluon saturation, thermalization and flow.
The formation of quarkonium bound states from interactions in which multiple
heavy quark-antiquark pairs are initially produced is examined in general.
Results from statistical hadronization and kinetic models are summarized. New
predictions from the kinetic model for J/Psi at RHIC are presented.Comment: Based on invited plenary talk at Strange Quark Matter 2004, Cape
Town, South Africa, September 15-20, 2004, references completed, published in
J. Phys. G: Nucl. Part. Phys. 31 (2005) S641-S64
Status and overview of development of the Silicon Pixel Detector for the PHENIX experiment at the BNL RHIC
We have developed a silicon pixel detector to enhance the physics
capabilities of the PHENIX experiment. This detector, consisting of two layers
of sensors, will be installed around the beam pipe at the collision point and
covers a pseudo-rapidity of | \eta | < 1.2 and an azimuth angle of | \phi | ~
2{\pi}. The detector uses 200 um thick silicon sensors and readout chips
developed for the ALICE experiment. In order to meet the PHENIX DAQ readout
requirements, it is necessary to read out 4 readout chips in parallel. The
physics goals of PHENIX require that radiation thickness of the detector be
minimized. To meet these criteria, the detector has been designed and
developed. In this paper, we report the current status of the development,
especially the development of the low-mass readout bus and the front-end
readout electronics.Comment: 9 pages, 8 figures and 1 table in DOCX (Word 2007); PIXEL 2008
workshop proceedings, will be published in the Proceedings Section of
JINST(Journal of Instrumentation
Quarkonia Production in Hot and Cold Matters
Quarkonia were predicted to be suppressed in the "hot" deconfined matter
known as the Quark Gluon Plasma (QGP), but they were also seen to suffer from
"cold" nuclear matter effects (parton shadowing, nuclear absorption...). Both
at SPS and RHIC, suppression beyond nuclear effects was observed, but the
rapidity dependence of the RHIC result is not easy to interpret. I review here
the current status of these results, their possible interpretations and the new
measurements that could provide insights on quarkonia suppression. Some of them
were presented at this conference.Comment: 8 pages, 4x2 figures, to appear in the proceedings of Quark Matter
2008: 20th International Conference on Ultra-Relativistic Nucleus Nucleus
Collisions (QM 2008), Jaipur, India, 4-10 Feb 2008. Version 3 accepted by
editor. Figure 3 correcte
Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions
This report reviews the study of open heavy-flavour and quarkonium production
in high-energy hadronic collisions, as tools to investigate fundamental aspects
of Quantum Chromodynamics, from the proton and nucleus structure at high energy
to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is
given to the lessons learnt from LHC Run 1 results, which are reviewed in a
global picture with the results from SPS and RHIC at lower energies, as well as
to the questions to be addressed in the future. The report covers heavy flavour
and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus
collisions. This includes discussion of the effects of hot and cold strongly
interacting matter, quarkonium photo-production in nucleus-nucleus collisions
and perspectives on the study of heavy flavour and quarkonium with upgrades of
existing experiments and new experiments. The report results from the activity
of the SaporeGravis network of the I3 Hadron Physics programme of the European
Union 7th Framework Programme
Measurement of the branching ratios of the decays Xi0 --> Sigma+ e- nubar and anti-Xi0 --> anti-Sigma+ e+ nu
From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Xi0
--> Sigma+ e- nubar candidates (with the subsequent Sigma+ --> p pi0 decay) and
555 anti-Xi0 --> anti-Sigma+ e+ nu candidates with background contamination of
215+-44 and 136+-8 events, respectively. From these samples, the branching
ratios BR(Xi0 --> Sigma+ e- nubar)= (2.51+-0.03stat+-0.09syst)E(-4) and
BR(anti-Xi0 --> anti-Sigma+ e+ nu)= (2.55+-0.14stat+-0.10syst)E(-4) were
measured allowing the determination of the CKM matrix element |Vus| =
0.209+0.023-0.028. Using the Particle Data Group average for |Vus| obtained in
semileptonic kaon decays, we measured the ratio g1/f1 = 1.20+-0.05 of the
axial-vector to vector form factors.Comment: 16 pages, 11 figures Submitted to Phys.Lett.
First observation of the KS->pi0 gamma gamma decay
Using the NA48 detector at the CERN SPS, 31 KS->pi0 gamma gamma candidates
with an estimated background of 13.7 +- 3.2 events have been observed. This
first observation leads to a branching ratio of BR(KS->pi0 gamma gamma) = (4.9
+- 1.6(stat) +- 0.9(syst)) x 10^-8 in agreement with Chiral Perturbation theory
predictions.Comment: 10 pages, 4 figures submitted to Phys. Lett.
- …