The p_{T}-differential cross sections of prompt charm-strange baryons Ξ_{c}^{0} and Ξ_{c}^{+} were measured at midrapidity (|y|<0.5) in proton-proton (pp) collisions at a center-of-mass energy ...sqrts=13 TeV with the ALICE detector at the LHC. The Ξ_{c}^{0} baryon was reconstructed via both the semileptonic decay (Ξ^{-}e^{+}ν_{e}) and the hadronic decay (Ξ^{-}π^{+}) channels. The Ξ_{c}^{+} baryon was reconstructed via the hadronic decay (Ξ^{-}π^{+}π^{+}) channel. The branching-fraction ratio BR(Ξ_{c}^{0}→Ξ^{-}e^{+}ν_{e})/BR(Ξ_{c}^{0}→Ξ^{-}π^{+})=1.38±0.14(stat)±0.22(syst) was measured with a total uncertainty reduced by a factor of about 3 with respect to the current world average reported by the Particle Data Group. The transverse momentum (p_{T}) dependence of the Ξ_{c}^{0}- and Ξ_{c}^{+}-baryon production relative to the D^{0} meson and to the Σ_{c}^{0,+,++}- and Λ_{c}^{+}-baryon production are reported. The baryon-to-meson ratio increases toward low p_{T} up to a value of approximately 0.3. The measurements are compared with various models that take different hadronization mechanisms into consideration. The results provide stringent constraints to these theoretical calculations and additional evidence that different processes are involved in charm hadronization in electron-positron (e^{+}e^{-}) and hadronic collisions.
A small-size prototype of a new Ring Imaging Cherenkov (RICH) detector using for the first time pressurized C4F8O radiator gas and a photon detector consisting of MWPC equipped with a CsI ...photocathode has been built and tested at the PS accelerator at CERN. It contained all the functional elements of the detector proposed as Very High Momentum Particle Identification (VHMPID) upgrade for the ALICE experiment at LHC to provide charged hadron track-by-track identification in the momentum range starting from 5 potentially up to 25 GeV/c. In the paper the equipment and its elements are described and some characteristic test results are shown.
The production of KFormula: see text(892)Formula: see text and Formula: see text(1020) mesons has been measured in p-Pb collisions at Formula: see textFormula: see text 5.02 TeV. KFormula: see text ...and Formula: see text are reconstructed via their decay into charged hadrons with the ALICE detector in the rapidity range Formula: see text. The transverse momentum spectra, measured as a function of the multiplicity, have a pFormula: see text range from 0 to 15 GeV/
for KFormula: see text and from 0.3 to 21 GeV/
for Formula: see text. Integrated yields, mean transverse momenta and particle ratios are reported and compared with results in pp collisions at Formula: see textFormula: see text 7 TeV and Pb-Pb collisions at Formula: see textFormula: see text 2.76 TeV. In Pb-Pb and p-Pb collisions, KFormula: see text and Formula: see text probe the hadronic phase of the system and contribute to the study of particle formation mechanisms by comparison with other identified hadrons. For this purpose, the mean transverse momenta and the differential proton-to-Formula: see text ratio are discussed as a function of the multiplicity of the event. The short-lived KFormula: see text is measured to investigate re-scattering effects, believed to be related to the size of the system and to the lifetime of the hadronic phase.
Measurements of charged jet production as a function of centrality are presented for p-Pb collisions recorded at Formula: see text TeV with the ALICE detector. Centrality classes are determined via ...the energy deposit in neutron calorimeters at zero degree, close to the beam direction, to minimise dynamical biases of the selection. The corresponding number of participants or binary nucleon-nucleon collisions is determined based on the particle production in the Pb-going rapidity region. Jets have been reconstructed in the central rapidity region from charged particles with the anti-Formula: see text algorithm for resolution parameters Formula: see text and Formula: see text in the transverse momentum range 20 to 120 GeV/
. The reconstructed jet momentum and yields have been corrected for detector effects and underlying-event background. In the five centrality bins considered, the charged jet production in p-Pb collisions is consistent with the production expected from binary scaling from pp collisions. The ratio of jet yields reconstructed with the two different resolution parameters is also independent of the centrality selection, demonstrating the absence of major modifications of the radial jet structure in the reported centrality classes.
We report on the inclusive production cross sections of Formula: see text, Formula: see text, Formula: see text(1S), Formula: see text(2S) and Formula: see text(3S), measured at forward rapidity with ...the ALICE detector in Formula: see text collisions at a center-of-mass energy Formula: see text TeV. The analysis is based on data collected at the LHC and corresponds to an integrated luminosity of 1.23 pbFormula: see text. Quarkonia are reconstructed in the dimuon-decay channel. The differential production cross sections are measured as a function of the transverse momentum Formula: see text and rapidity
, over the Formula: see text ranges Formula: see text GeV/
for Formula: see text, Formula: see text GeV/
for all other resonances, and for Formula: see text. The cross sections, integrated over Formula: see text and
, and assuming unpolarized quarkonia, are Formula: see text Formula: see textb, Formula: see text Formula: see textb, Formula: see text nb, Formula: see text nb and Formula: see text nb, where the first uncertainty is statistical and the second one is systematic. These values agree, within at most Formula: see text, with measurements performed by the LHCb collaboration in the same rapidity range.
PDF
