Strangeness production in two-particle azimuthal correlations on the near and away side measured with ALICE in pp collisions at 7 TeV

Two-particle azimuthal correlations allow one to study high-$p_{\rm T}$ parton fragmentation without full jet reconstruction. Enhancements of the azimuthal correlations are seen at $\Delta \varphi \approx 0$ and $\Delta \varphi \approx \pi$, resulting from back-to-back jet fragmentation in the parton center-of-mass system. We present the current status of the study of correlations between charged trigger particles and associated strange baryons ($\Lambda$) and mesons (K$_{S}^{0}$) in pp collisions at $\sqrt{s}$ = 7 TeV. A data-driven feeddown correction for $\Lambda$ is also presented, which could allow a more accurate calculation of the primary $\Lambda/$K$_{S}^{0}$ ratio in jets and the underlying event.Comment: 5 pages, 4 figures, Proceedings of the Second Annual Conference on Large Hadron Collider Physics (LHCP 2014), June 2-7, 2014, New Yor

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

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Transverse Momentum Evolution of Hadron-V0 Correlations in Proton-Proton Collisions at (sNN)\sqrt(s_NN) = 7 TeV

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, is capable of accelerating beams of protons (pp) and heavy-ions (Pb+Pb) up to nearly the speed of light, which corresponds to center of mass energies of sqrt(s_NN) = 7 TeV and sqrt(s_NN) = 2.76 TeV, respectively. The goal of the pp program is to investigate physics of and beyond the standard model, while the heavy-ion program attempts to characterize the properties of a new state of matter, called the Quark Gluon Plasma. The main aim of this dissertation is to identify particle production mechanisms in pp collisions, also as a reference for possible modifications due to the plasma formation in heavy-ion collisions. Two-particle azimuthal correlation measurements were employed, which allow the study of high-pT parton fragmentation without full jet reconstruction. We present the results of correlations between charged trigger particles and associated strange baryons (Lambda) and mesons (K0S). Enhancements of the azimuthal correlations are seen at delta-phi = 0 and delta-phi = pi, resulting from back-to-back jet fragmentation in the parton center-of-mass system. Two model fit functions were introduced to characterize the properties of the jet peaks. Hard and soft yields were separated using the ZYAM method and extracted yields were compared with pQCD inspired models and inclusive spectra. The analysis was performed in different multiplicity bins to detect possible enhancements of Lambda or K0S yields and the Lambda/K0S ratio. The latter was observed in high multiplicity Pb+Pb collisions and interpreted as a novel production mechanism in the deconfined medium produced at the LHC. A novel data-driven feed-down correction for Lambdas is also introduced, which could allow a more accurate calculation of the primary Lambda

TRANSVERSE MOMENTUM EVOLUTION OF HADRON-V0 CORRELATIONS IN PP COLLISIONS AT 7 TEV

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, is capable of accelerating beams of protons (pp) and heavy-ions (Pb+Pb) up to nearly the speed of light, which corresponds to center of mass energies of 7 TeV and 2.76 TeV, respectively. The goal of the pp program is to investigate physics of and beyond the standard model, while the heavy-ion program attempts to characterize the properties of a new state of matter, called the Quark Gluon Plasma. The main aim of this dissertation is to identify particle production mechanisms in pp collisions, also as a reference for possible modifications due to the plasma formation in heavy-ion collisions. Two-particle azimuthal correlation measurements were employed, which allow the study of high-pT parton fragmentation without full jet reconstruction. We present the results of correlations between charged trigger particles and associated strange baryons and mesons. Enhancements of the azimuthal correlations are seen at dphi= 0 and dphi= pi, resulting from back-to-back jet fragmentation in the parton center-of-mass system. Two model fit functions were introduced to characterize the properties of the jet peaks. Hard and soft yields were seperated using the ZYAM method and extracted yields were compared with pQCD inspired models and inclusive spectra. The analysis was performed in different multiplicity bins to detect possible enhancements of baryons or meson yields and the baryon/meson ratio. The latter was observed in high multiplicity Pb+Pb collisions and interpreted as a novel production mechanism in the deconfined medium produced at the LHC. A novel data-driven feeddown correction for Lambda is also introduced, which could allow a more accurate calculation of the primary Xi.Physics, Department o

Where Brain, Body and World Collide

The production cross section of electrons from semileptonic decays of beauty hadrons was measured at mid-rapidity (|y| < 0.8) in the transverse momentum range 1 < pt < 8 Gev/c with the ALICE experiment at the CERN LHC in pp collisions at a center of mass energy sqrt{s} = 7 TeV using an integrated luminosity of 2.2 nb^{-1}. Electrons from beauty hadron decays were selected based on the displacement of the decay vertex from the collision vertex. A perturbative QCD calculation agrees with the measurement within uncertainties. The data were extrapolated to the full phase space to determine the total cross section for the production of beauty quark-antiquark pairs