15,486 research outputs found

    The Physics of ALICE HLT Trigger Modes

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    We discuss different physics cases, mainly of the ALICE TPC, such as pile-up, jets in pp and PbPb, Bottonium and Charmonium spectroscopy, and there corresponding demands on the ALICE High Level Trigger (HLT) System. We show that compression and filter strategies can reduce the data volume by factors of 5 to 10. By reconstructing (sub)events with the HLT, background events can be rejected with a factor of up to 100 while keeping the signal (low cross-section probes). Altogether the HLT improves the discussed physics capabilities of ALICE by a factor of 5-100 in terms of statistics.Comment: 25 pages, 4 figure

    Validity of the Hadronic Freeze-Out Curve

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    We analyze hadro-chemical freeze-out in central Pb+Pb collisions at CERN SPS energies, employing the hybrid version of UrQMD which models hadronization by the Cooper-Frye mechanism, and matches to a final hadron-resonance cascade. We fit the results both before and after the cascade stage using the Statistical Hadronization Model, to assess the effect of the cascade phase. We observe a strong effect on antibaryon yields except anti-{\Omega}, resulting in a shift in T and {\mu}_B. We discuss the implications for the freeze-out curve.Comment: 5 pages, 8 figures. To appear in the proceedings of Quark Matter 2011, the XXII International Conference on Ultrarelativistic Nucleus-Nucleus Collision

    Hadronic Freeze-Out in A+A Collisions meets the Lattice QCD Parton-Hadron Transition Line

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    We analyze hadrochemical freeze-out in central Pb+Pb collisions at CERN SPS and LHC energies. Employing the UrQMD hybrid transport model we study the effects of the final hadron/resonance expansion phase on the hadron multiplicities established at hadronization. The bulk meson yields freeze out directly at hadronization whereas the baryon-antibaryon sector is subject to significant alterations, due to annihilation and regeneration processes. We quantify the latter changes by survival factors for each species which are applied to modify the statistical model predictions for the data. The modified SM analysis recovers the hadronization points, which coincide with the recent lattice QCD predictions of the parton-hadron transition line at finite baryochemical potential.Comment: Proceedings of the 8th International Workshop on Critical Point and Onset of Deconfinement, March 11 to 15, 2013 Napa, California, US

    Quark Matter 99 Summary: Hadronic Signals

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    I review the new data presented at QM99. The main emphasis is placed on the CERN SPS hadron production systematics concluding that the boundary between a partonic and a hadronic phase has now been located at T=180±10MeVT=180 \pm10\:MeV and ϵ1GeV\epsilon \approx 1 \:GeV per fm3fm^3.Comment: 18 page

    Fetal heterotaxy with tricuspid atresia, pulmonary atresia, and isomerism of the right atrial appendages at 22 weeks.

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    We report the accurate prenatal diagnosis at 22 weeks gestation of right atrial isomerism in association with tricuspid atresia. Several distinctive sonographic features of isomerism of the right atrial appendages were present in this fetus: complex cardiac abnormality, ventriculoarterial discordance, juxtaposition of the aorta and the inferior vena cava to the right side, pulmonary atresia, and anomalous pulmonary venous return to the morphological right atrium. Tricuspid atresia, which is an extremely rare lesion within heterotaxy spectrum disorders, was present. Postnatal investigations confirmed all prenatally diagnosed abnormalities, with additional findings of pulmonary atresia with discontinuous pulmonary arteries and bilateral arterial ducts, asplenia, and bilateral eparterial bronchi. To our knowledge, tricuspid atresia in the setting of isomerism of the right atrial appendages has not previously been diagnosed or reported prenatally. Because of the complexity of cardiac lesions that may be present in cases of atrial isomerism, these disorders should be considered even if sonographic findings are uncommon or atypical

    Globally Polarized Quark-gluon Plasma in Non-central A+A Collisions

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    Produced partons have large local relative orbital angular momentum along the direction opposite to the reaction plane in the early stage of non-central heavy-ion collisions. Parton scattering is shown to polarize quarks along the same direction due to spin-orbital coupling. Such global quark polarization will lead to many observable consequences, such as left-right asymmetry of hadron spectra, global transverse polarization of thermal photons, dileptons and hadrons. Hadrons from the decay of polarized resonances will have azimuthal asymmetry similar to the elliptic flow. Global hyperon polarization is predicted within different hadronization scenarios and can be easily tested.Comment: 4 pages in RevTex with 2 postscript figures, an erratum is added to the final published versio
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