arXiv subjects

Andre Mischke

Publications and source records attributed to Andre Mischke.

12 recordsLinked to original sources

arXiv2013

Overview on heavy flavour measurements in lead-lead collisions at the CERN-LHC

High energy collisions of heavy atomic nuclei allow to create and carefully study a high-density, colour-deconfined state of strongly-interacting matter. According to calculations from lattice Quantum-Chromodynamics, under the conditions of high energy density and temperature reached in such collisions, the phase transition to a quark-gluon plasma (QGP) is expected to occur, where the colour confinement of quarks and gluons into hadrons should vanish and chiral symmetry should be restored. Heavy-flavour particles, containing charm and beauty, are unique probes of the conditions of the medium formed in nucleus-nucleus collisions at high energy. In this report recent measurements on open and hidden heavy-flavour production in lead-lead collisions at CERN's Large Hadron Collider are presented and discussed.

hep-ex↗

arXiv2012

Open heavy flavour nuclear modification factor in ALICE

The ALICE experiment has measured charm and beauty production in pp and Pb-Pb collisions at sqrt(s) = 2.76 and 7 TeV and sqrt(sNN) = 2.76 TeV, respectively, via the exclusive reconstruction of hadronic D meson decays and semi-leptonic D and B meson decays. In this contribution, recent results on the nuclear modification factor for open charmed mesons and heavy-flavour decay electrons at central rapidity and muons at forward rapidity are presented and discussed.

nucl-ex↗

arXiv2011

Jet-like correlations of heavy-flavor particles - from RHIC to LHC

Measurements at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory have revealed strong modification of the jet structure in high-energy heavy-ion collisions, which can be attributed to the interaction of hard scattered partons with the hot and dense QCD matter. The study of heavy-quark (charm and bottom) production in such collisions provides key tests of parton energy-loss models and, thus, yields profound insight into the properties of the produced matter. The high-pT yield of heavy-flavor decay electrons exhibits an unexpected large suppression. Since those single electrons have contributions from charm and bottom decays an experimental method is needed to investigate them separately. Heavy-flavor particle correlations provide information about the underlying production mechanism. In this contribution, a review on recent measurements on azimuthal correlations of single electrons and open charmed mesons at RHIC and perspectives of such measurements at the CERN-Large Hadron Collider (LHC) are presented. Moreover, it has been shown that next-to-leading-order (NLO) QCD processes, such as gluon splitting, become important at LHC energies. It will be demonstrated how this contribution can be determined through the measurement of the charm content in jets.

nucl-ex↗

arXiv2011

Heavy-flavour production in pp and Pb-Pb collisions at ALICE

In this contribution, recent ALICE measurements of the production cross section of single electrons, single muons and open charmed mesons in proton-proton collisions at sqrt(s) = 7 TeV are reported. The data are compared to next-to-leading-order perturbative QCD calculations. First open charm signals in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV are shown.

hep-ex↗

arXiv2010

Heavy-flavour production in hot quark matter

Recent results from RHIC and first measurements from the ALICE experiment at the CERN-Large Hadron Collider (LHC) on open heavy-flavour are presented. We focus on RHIC measurements of single electrons and jet-like heavy-flavour particle correlations. First D meson signals from 7 TeV proton-proton collisions in ALICE are discussed. Next-to-leading-order QCD processes, such as gluon splitting, become important at LHC energies and its contribution can be accesses by the measurement of the "charm content in jets".

nucl-ex↗

arXiv2009

Heavy flavour production at LHC

The Large Hadron Collider (LHC) will open a new era in high energy physics. The expected large cross section for heavy flavour production in proton-proton collisions at $\sqrt{s}$ = 14 TeV will allow detailed studies of the production mechanisms and an extensive test of Quantum Chromodynamics. Since charm and beauty has been proposed as a good probe to study hot and dense QCD matter, the understanding of the production mechanisms in elementary proton-proton collisions is of primary importance as a reference for studies in heavy-ion collisions. In the early phase of LHC operation the experiments will focus on the investigation of the heavy flavour production mechanisms.

hep-ex↗

arXiv2009

A new correlation method to identify and separate charm and bottom production processes at RHIC

Electrons from semileptonic decays of heavy-flavor mesons (D and B) allow to study the energy loss of heavy-quarks in nuclear collisions at sqrt(s) = 200 GeV at RHIC. Since pQCD calculations have shown that the crossing point where bottom decay electrons start to dominate over charm decay electrons is largely unknown, an urgent need arises to access the relative contributions independently. A correlation method is proposed to identify and separate charm and bottom production processes on a statistical basis through tagging of their decay electrons and open charmed mesons. The feasibility for this method is demonstrated using PYTHIA and MC@NLO simulations. The latter allows to estimate the complete NLO contributions, including e.g. gluon-splitting diagrams.

hep-ph↗

arXiv2007

Recent heavy flavor results from STAR

We report on recent heavy flavor measurements from the STAR experiment at RHIC. The measured charm cross section in heavy-ion collisions scales with the number of binary collisions, which is an indication for exclusive charm production in the initial state of the collision. The observed strong suppression of non-photonic electrons at high $\pt$ in Au+Au collisions together with the azimuthal correlation measurements in p+p collisions imply a suppression of $B$ production in heavy-ion collisions. We also present recent measurements of the $Υ$ cross section in p+p collisions.

nucl-ex↗

arXiv2007

Topological reconstruction of open charm mesons using electron tagging

We present first results on the topological reconstruction of open charm mesons in p+p collisions at $\snn$ = 200 GeV using electron tagging. The analysis makes use of the full acceptance of the STAR electromagnetic calorimeter during Run VI data taking. A clear D$^0$ signal is obtained with a remarkable signal-to-background ratio of about 1/7 and a signal significance of about 4. The azimuthal correlation distribution of the subleading electrons associated with open charm mesons exhibits a two-peak structure. We found first indications for prompt charm meson pair production. This correlation technique allows detailed energy loss measurements of open charm mesons in heavy-ion collisions.

nucl-ex↗

arXiv2005

Recent high pT measurements in STAR

After five years of data taking, the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory provides precise measurements of particle production at high transverse momentum in p-p, d-Au, and Au-Au collisions at sqrt(s) = 200 GeV. We review recent results on the flavor dependence of high pT particle suppression and hadron particle spectra at sqrt(s) = 62.4 GeV. New results on two-particle angular correlations for identified trigger particles and for low momentum associated charged hadrons in p-p and Au-Au as well as near-side $Δη$ correlations will be presented and discussed.

nucl-ex↗

arXiv2005

Neutral pion production in d-Au collisions at sqrt(s_NN) = 200 GeV

In this paper, preliminary results are presented on high-$p_T$ inclusive neutral pion measurements in d-Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV in the pseudo-rapidity range $0<η<1$. The photons of the decay $pi^0\toγγ$ are detected in the Barrel Electromagnetic Calorimeter of the STAR experiment at RHIC. The analysis of this first BEMC hadron measurement is described in detail. The results are compared to earlier RHIC findings. Furthermore, the obtained $π^{0}$ invariant differential cross sections show good agreement with next-to-leading order (NLO) perturbative QCD calculations.

nucl-ex↗

arXiv2003

Strangeness Production in Heavy Ion Collisions at SPS Energies

The NA49 collaboration has taken data of central Pb-Pb collisions at beam energies from 20 to 158 GeV per nucleon. The large acceptance of the detector allows to study particle yields in full phase space. In this paper we present recent results on strangeness production (K, $Λ$ and $ϕ$) in this energy range and compare to measurements at lower and higher energies. The K$^+/π^+$ and $Λ/π$ ratio shows a pronounced maximum around 30 A$\cdot$GeV, whereas the K$^-/π^-$ and $\barΛ/π$ ratio exhibits a continuous rise. The $ϕ/π$ ratio also increases monotonically with beam energy. First results on multi-strange hyperon production at lower SPS energies are presented.

hep-ex↗