Strange quark and particle production is studied at the LHC with unprecedented high beam energies in both heavy-ion and proton-proton collisions: on the one hand, strangeness is used for investigating chemical equilibration and bulk properties; on the other hand, strange particles contribute to probe different kinematical domains, from the one where collective phenomena are at play up to the region dominated by pQCD-calculable processes. We highlight the suitability of the ALICE experiment for this topic, presenting our latest measurements and comparing them to models.
We present new measurements related to spin alignment of $mathrm{K^{*0}}$ vector mesons at mid-rapidity for Pb-Pb collisions at $sqrt{s_{mathrm{NN}}}$ = 2.76 and 5.02 TeV. The spin alignment measurements are carried out with respect to production plane and second order event plane. At low $p_{mathrm{T}}$ the spin density matrix element $rho_{00}$ for $mathrm{K^{*0}}$ is found to have values slightly below 1/3, while it is consistent with 1/3, i.e. no spin alignment, at high $p_{mathrm{T}}$. Similar values of $rho_{00}$ are observed w.r.t. both production plane and event plane. Within statistical and systematic uncertainties, $rho_{00}$ values are also found to be independent of $sqrt{s_{mathrm{NN}}}$. $rho_{00}$ also shows centrality dependence with maximum deviation from 1/3 for mid-central collisions w.r.t. both the kinematic planes. The measurements for $mathrm{K^{*0}}$ in pp collisions at $sqrt{s}$ = 13 TeV and for $mathrm{K^{0}_{S}}$ (a spin 0 hadron) in 20-40% central Pb-Pb collisions at $sqrt{s_{mathrm{NN}}}$ = 2.76 TeV are consistent with no spin alignment.
The ALICE experiment at LHC is mainly dedicated to heavy-ion physics. An overview of its performances, some predictions related to its first measurements and QGP observable measurements will be given.
The event-by-event fluctuations of identified particles in ultrarelativistic nucleus-nucleus collisions give information about the state of matter created in these collisions as well as the phase diagram of nuclear matter. In this proceedings, we present the latest results from ALICE on the centrality and pseudorapidity dependence of net-proton fluctuations, which are closely related to net-baryon fluctuations, as well as net-kaon and net-pion fluctuations. The effects of volume fluctuations and global baryon conservation on these observables are discussed. Furthermore, the correlated fluctuations between different particle species, quantified by the observable $ u_{dyn}$, are also shown as functions of multiplicity and collision energy and are compared with Monte Carlo models. These measurements are performed in Pb-Pb collisions at $sqrt{s_{mathrm{NN}}} = 2.76$ TeV using the novel Identity Method and take advantage of the excellent particle identification capabilities of ALICE.
The ALICE experiment at the Large Hadron Collider (LHC) at CERN consists of a central barrel, a muon spectrometer and additional detectors for trigger and event classification purposes. The low transverse momentum threshold of the central barrel gives ALICE a unique opportunity to study the low mass sector of central exclusive production at the LHC.
K. Schweda (Research Division
,ExtreMe Matter Institute EMMI
,GSIn Helmholtzzentrum fur Schwerionenforschung
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(2014)
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"Prompt production of D mesons with ALICE at the LHC"
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Kai O. Schweda
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