1,060 research outputs found
Summary of recent experimental results on strangeness production
This article summarises the highlights of the recent experimental findings on
strangeness production presented at the 16th edition of the {\it International
Conference on Strangeness in Quark Matter} in Berkeley. Results obtained by
eight large experimental collaborations (ALICE, ATLAS, CMS, HADES, LHCb, NA-61,
PHENIX, STAR) spanning a large range in centre-of-mass energy and a variety of
collision systems were presented at the conference. The article does not aim at
being a complete review, but rather at connecting the experimental highlights
of the different collaborations and at pointing towards questions which should
be addressed by these experiments in future.Comment: Proceedings of the experimental summary talk -- Strangeness in Quark
Matter conference Berkeley 201
Particle Identification in the ALICE Experiment
The particle identification capabilities of the ALICE experiment are unique
among the four major LHC experiments. The working principles and excellent
performance of the central barrel detectors in a high-multiplicity environment
are presented as well as two physics examples: the extraction of transverse
momentum spectra of charged pions, kaons, protons, and the observation of the
anti-4He-nucleus.Comment: Quark Matter 2011 Proceeding
Confronting fluctuations of conserved charges in central nuclear collisions at the LHC with predictions from Lattice QCD
We construct net baryon number and strangeness susceptibilities as well as
correlations between electric charge and strangeness from experimental data of
the ALICE Collaboration at the CERN LHC. The data were taken in Pb-Pb
collisions at =2.76 TeV. The resulting fluctuations and
correlations are consistent with Lattice QCD results at the chiral crossover
pseudocritical temperature MeV. This agreement lends strong
support to the assumption that the fireball created in these collisions is of
thermal origin and exhibits characteristic properties expected in QCD at the
transition from the quark gluon plasma to the hadronic phase. The volume of the
fireball for one unit of rapidity at is found to exceed 4000 fm. A
detailed discussion on uncertainties in the temperature and volume of the
fireball is presented. The results are linked to pion interferometry
measurements and predictions from percolation theory.Comment: 7 pages, 4 figures Accepted for publication in PL
On coalescence as the origin of nuclei in hadronic collisions
The origin of weakly-bound nuclear clusters in hadronic collisions is a key
question to be addressed by heavy-ion collision (HIC) experiments. The measured
yields of clusters are approximately consistent with expectations from
phenomenological statistical hadronisation models (SHMs), but a theoretical
understanding of the dynamics of cluster formation prior to kinetic freeze out
is lacking. The competing model is nuclear coalescence, which attributes
cluster formation to the effect of final state interactions (FSI) during the
propagation of the nuclei from kinetic freeze out to the observer. This
phenomenon is closely related to the effect of FSI in imprinting femtoscopic
correlations between continuum pairs of particles at small relative momentum
difference. We give a concise theoretical derivation of the
coalescence--correlation relation, predicting nuclear cluster spectra from
femtoscopic measurements. We review the fact that coalescence derives from a
relativistic Bethe-Salpeter equation, and recall how effective quantum
mechanics controls the dynamics of cluster particles that are nonrelativistic
in the cluster centre of mass frame. We demonstrate that the
coalescence--correlation relation is roughly consistent with the observed
cluster spectra in systems ranging from PbPb to pPb and pp collisions. Paying
special attention to nuclear wave functions, we derive the coalescence
prediction for hypertriton and show that it, too, is roughly consistent with
the data. Our work motivates a combined experimental programme addressing
femtoscopy and cluster production under a unified framework. Upcoming pp, pPb
and peripheral PbPb data analysed within such a programme could stringently
test coalescence as the origin of clusters.Comment: 24 pages, 10 figure
Confronting fluctuations of conserved charges in central nuclear collisions at the LHC with predictions from Lattice QCD
We construct net baryon number and strangeness susceptibilities as well as correlations between electric charge, strangeness and baryon number from experimental data at midrapidity of the ALICE Collaborationat CERN. The data were taken in central Pb–Pb collisions at √sNN = 2.76 TeV and cover one unit of rapidity. The resulting fluctuations and correlations are consistent with Lattice QCD results at the chiral crossover pseudocritical temperature Tc ≃ 155 MeV. This agreement lends strong support to the assumption that the fireball created in these collisions is of thermal origin and exhibits characteristic properties expected in QCD at the transition from the quark gluon plasma to the hadronic phase. The volume of the fireball for one unit of rapidity at Tc is found to exceed 3000 fm³. A detailed discussion on uncertainties in the temperature and volume of the fireball is presented. The results are linked to pion interferometry measurements and predictions from percolation theory
Thoughts on opportunities in high-energy nuclear collisions
This document reflects thoughts on opportunities from high-energy nuclear
collisions in the 2020s.Comment: 10 pages, pd
Asynchronous coupling of hybrid models for efficient simulation of multiscale systems
We present a new coupling approach for the time advancement of multi-physics models of multiscale systems. This extends the method of E et al. (2009) [5] to deal with an arbitrary number of models. Coupling is performed asynchronously, with each model being assigned its own timestep size. This enables accurate long timescale predictions to be made at the computational cost of the short timescale simulation. We propose a method for selecting appropriate timestep sizes based on the degree of scale separation that exists between models. A number of example applications are used for testing and benchmarking, including a comparison with experimental data of a thermally driven rarefied gas flow in a micro capillary. The multiscale simulation results are in very close agreement with the experimental data, but are produced almost 50,000 times faster than from a conventionally-coupled simulation
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
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