3,142 research outputs found
Charm and beauty of the Large Hadron Collider
With the acceleration of lead nuclei in the LHC, heavy-ion physics will enter
a new energy domain. One of the main novelties introduced by the 30-fold
energy-jump from RHIC to the LHC is the abundant heavy-quark production. After
discussing a few examples of physics issues that can be addressed using heavy
quarks, we present a selection of results on the expected experimental
capability of ALICE, the dedicated heavy-ion experiment at the LHC, in the
open-heavy-flavour sector.Comment: 10 pages, 5 figures. Invited talk at Strangeness in Quark Matter
(SQM) 2004, Cape Town, South Africa, 15-20 September 2004. Submitted to J.
Phys.
Correlations of Heavy Quarks Produced at Large Hadron Collider
We study the correlations of heavy quarks produced in relativistic heavy ion
collisions and find them to be quite sensitive to the effects of the medium and
the production mechanisms. In order to put this on a quantitative footing, as a
first step, we analyze the azimuthal, transverse momentum, and rapidity
correlations of heavy quark-anti quark () pairs in
collisions at (). This sets the stage for the
identification and study of medium modification of similar correlations in
relativistic collision of heavy nuclei at the Large Hadron Collider. Next we
study the additional production of charm quarks in heavy ion collisions due to
multiple scatterings, {\it viz.}, jet-jet collisions, jet-thermal collisions,
and thermal interactions. We find that these give rise to azimuthal
correlations which are quite different from those arising from prompt initial
production at leading order and at next to leading order.Comment: 26 pages, 15 figures. Three new figures added, comparison to
experimental data included, abstract and discussion expande
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
Measurement of the nuclear modification factor of electrons from heavy-flavour decays at mid-rapidity in Pb-Pb collisions at = 2.76 TeV with ALICE
We present results on inclusive electrons for 1.5 6 GeV/
in {Pb-Pb} collisions at = 2.76 TeV measured with ALICE at
the LHC and compare these to a cocktail of background electron sources. The
excess of electrons beyond the cocktail at high momenta ({ 3.5
GeV/}) is attributed to electrons from heavy-flavour decays. The
corresponding nuclear modification factor indicates heavy-flavour suppression
by a factor of 1.5-4.Comment: 4 pages; 4 figures; QM 2011 proceeding
Measuring beauty production in Pb-Pb collisions at the LHC via single electrons in ALICE
We present the expected ALICE performance for the measurement of the
p_t-differential cross section of electrons from beauty decays in central Pb-Pb
collisions at the LHC.Comment: 4 pages, 2 figures, proceeding of poster presentation at "Quark
Matter 2005
D meson nuclear modification factors in Pb-Pb collisions at {\surd}sNN = 2.76 TeV, measured with the ALICE detector
The ALICE experiment has measured the D meson production in pp and Pb-Pb
collisions at the LHC at {\surd}s = 7 and 2.76 TeV and {\surd}sNN = 2.76 TeV
respectively, via the exclusive reconstruction of hadronic decay channels. The
analyses of the D0{\to}K-pi+ and D+{\to}K-pi+pi+ channels will be described and
the preliminary results for the D0 and D+ nuclear modification factor will be
presented.Comment: Proceedings of Quark Matter 2011 conference. 4 pages, 4 figures. The
slides of the talk can be found at the link:
http://indico.cern.ch/materialDisplay.py?contribId=591&sessionId=53&materialId=slides&confId=3024
Heavy-flavour production in Pb-Pb collisions at the LHC, measured with the ALICE detector
We present the first results from the ALICE experiment on the nuclear
modification factors for heavy-flavour hadron production in Pb-Pb collisions at
sqrt{s_NN}=2.76 TeV. Using proton-proton and lead-lead collision samples at
sqrt{s}=7 TeV and sqrt{s_NN}=2.76 TeV, respectively, nuclear modification
factors R_AA(pt) were measured for D mesons at central rapidity (via displaced
decay vertex reconstruction), and for electrons and muons, at central and
forward rapidity, respectively.Comment: 8 pages, 5 figures, plenary talk at Quark Matter 2011, Annecy, Franc
Physicochemical parameters and antibiotics residuals in Algerian honey
The aim of the present study was to evaluate the quality of 36 samples of different honey type supplied by local producers from Algeria in order to verify its compliance with the standards of Codex Alimentarius and European Union (EU). For that, five physicochemical parameters were analyzed using the HPLC method: hydroxyl-methyl furfural (HMF), sugars, diastase activity and search of antibiotic contamination with streptomycin and tetracycline. The physicochemical analyses of the Algerian honeys show that 56% of samples correspond to Codex standards and 44% not in conformity with the standards required by the Codex Alimentarius and EU, because part of the samples had one or more defects. The percentage not in conformity was due to the high rates of hydroxyl-methyl furfural, sucroseand also to the low enzyme level. Analysis performed by the laboratory to detect residues of tetracycline and streptomycin in honey have revealed insignificant traces of oxytetracycline in two samples of honey (0.03 ppb). From the present study, it is observed that the Algerian honey samples is not completely in agreement with the requirements of international honey standards which could be caused by inappropriate actions during processing and storage steps.Key words: Honey quality, sugar, diastase activity, hydroxymethylfurfural, antibiotic residues
Genitori migranti e figli con disabilit\ue0 Le rappresentazioni dei professionisti e le percezioni delle famiglie
Il contributo si occupa di un tema poco indagato nel panorama delle ricerche italiane ed europee, quello della disabilit\ue0 e della migrazione; su questo tema \u201cintrecciato\u201d la ricerca si pone come una delle prime a livello europeo. Dai primi dati della ricerca e da una prima analisi del materiale qualitativo e quantitativo, emerge: da parte degli insegnanti, la difficolt\ue0 di comunicazione e di coinvolgimento delle famiglie dovuta a rapporti frettolosi (necessit\ue0 di mediatori culturali e di tempo), a fronte di una discreta/buona collaborazione quando vi \ue9 coinvolgimento; da parte dei genitori, l\u2019enorme difficolt\ue0 nella quotidiana accessibilit\ue0 (case inadeguate ecc.); la non curanza di alcune realt\ue0 (questura, servizi, comune ecc.) a informarli correttamente e tempestivamente sui loro diritti; la totale assenza di qualunque aiuto - ad eccezione della scuola - quando i genitori si trovano in situazioni drammatiche; lo scarsissimo feeling con gli assistenti sociali; il fatalismo del destino del figlio che attenua il senso di colpa, senza connotarsi di progettualit\ue0; da parte dei professionisti, la necessit\ue0 che i genitori possano contare su una figura di riferimento (case-manager) presente sul territorio e su reti parentali e amicali culturalmente affini e/o meticciate; la rappresentazione di genitori in difficolt\ue0 per scarsa chiarezza nelle comunicazioni, a fronte di un\u2019immediata accettazione di sostegni. Da questa prima parziale lettura, la scuola risulta la realt\ue0 maggiormente in grado di corrispondere ai bisogni delle famiglie, accogliendole; ci\uf2 viene confermato dagli stessi insegnanti che richiedono, per\uf2, un maggior supporto dei servizi territoriali, anche riguardo all\u2019ampliamento della partecipazione delle famiglie migranti (con la presenza di mediatori culturali)
Multiplicity distributions inside parton cascades developing in a medium
The explanation of the suppression of high-pT hadron yields at RHIC in terms
of jet-quenching implies that the multiplicity distributions of particles
inside a jet and jet-like particle correlations differ strongly in
nucleus-nucleus collisions at RHIC or at the LHC from those observed at e+e- or
hadron colliders. We present a framework for describing the medium-induced
modification, which has a direct interpretation in terms of a probabilistic
medium-modified parton cascade, and which treats leading and subleading partons
on an equal footing. We show that our approach can account for the strong
suppression of single inclusive hadron spectra measured in Au-Au collisions at
RHIC, and that this implies a characteristic distortion of the single inclusive
distribution of soft partons inside the jet. We determine, as a function of the
jet energy, to what extent the soft fragments within a jet can be measured
above some momentum cut.Comment: 5 pages, 4 eps-figures; talk given at Hot Quarks 2006, Villasimius
(Sardinia, Italy), May 15-20, 200
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