scholarly journals Recent results from the ALICE Experiment at LHC

2018 ◽  
Vol 191 ◽  
pp. 01004
Author(s):  
Catalin Ristea
Keyword(s):  
System Size ◽  
Heavy Ion ◽  
Dense Medium ◽  
Production Flow ◽  
Alice Experiment ◽  
Final State ◽  
Proton Proton ◽  
Ion Collisions ◽  
Flow Phenomena ◽  
Nuclear Modification Factors

ALICE (A Large Ion Collider Experiment) at the LHC performed high statistics measurements in Pb-Pb collisions at the top LHC energy, complemented with large recent reference datasets in elementary proton-proton collisions at the same energy. Elementary pp collisions are serving as baseline for testing QCD properties and allow the study of the changes induced by the hot and dense medium produced in heavy ion collisions. Key observables like nuclear modification factors, jet production, flow phenomena and spectra for identified particles, related to the different stages of collision evolution, are presented and compared with the most recent results from p-Pb and Xe-Xe collisions, thus allowing to probe both initial cold nuclear matter and final state effects, combined with the system size dependence of the measurements.

scholarly journals Probing the hadronic phase with resonances of different lifetimes in Pb-Pb collisions with ALICE

2018 ◽  
Vol 171 ◽  
pp. 15001
Author(s):  
Neelima Agrawal
Keyword(s):  
Heavy Ion ◽  
High Energy ◽  
Special Focus ◽  
Alice Experiment ◽  
Comprehensive Overview ◽  
Final State ◽  
Hadronic Phase ◽  
Ion Collisions ◽  
Hadronic Resonances

The ALICE experiment has measured the production of a rich set of hadronic resonances, such as ρ(770)0, K*(892)0, ϕ(1020), ∑±(1385), Λ(1520) and Ξ*0 in pp, p-Pb and Pb-Pb collisions at various energies at the LHC. A comprehensive overview and the latest results are presented in this paper. Special focus is given to the role of hadronic resonances for the study of final-state effects in high-energy collisions. In particular, the measurement of resonance production in heavy-ion collisions has the capability to provide insight into the existence of a prolonged hadronic phase after hadronisation. The observation of the suppression of the production of Λ(1520) resonance in central Pb-Pb collisions at [see formula in PDF] =2.76 TeV adds further support to the existence of such a dense hadronic phase, as already evidenced by the ratios K*(892)0/K and ρ(770)0/π.

scholarly journals OPEN CHARM ANALYSIS ON THE FIRST PP COLLISIONS AT $\sqrt{s} = 7~{\rm TeV}$ WITH ALICE

2011 ◽  
Vol 02 ◽  
pp. 25-30 ◽  
Author(s):  
◽  
GIACOMO ORTONA
Keyword(s):  
Production Cross ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Nucleon Nucleon ◽  
Relativistic Heavy Ion Collisions ◽  
Alice Experiment ◽  
Proton Proton ◽  
Ion Collisions ◽  
Density State ◽  
Energy Domain

A Large Ion Collider Experiment (ALICE) is one of the four large experiments at the Large Hadron Collider (LHC), and the one dedicated to ultra relativistic heavy ion collisions, aiming at investigating the properties of the high-density state of QCD matter produced in such events. ALICE started to collect data in proton-proton collisions at the LHC at CERN in November 2009 (with a centre of mass energy [Formula: see text]). Since March 2010 data are being recorded at an energy of [Formula: see text] while from November 7 to December 6 LHC provided Pb-Pb collisions at an energy of [Formula: see text] per nucleon-nucleon pair. In Pb-Pb collisions heavy quarks are regarded as sensitive probes of the interaction dynamics between the parton and medium produced in the collisions, and the energies available at LHC will allow to study the production of heavy flavours with high statistics. Proton-proton data will be used to measure the heavy flavours production cross section to compare with perturbative QCD calculations in an unexplored energy domain and they will provide the reference for the study of Pb-Pb collisions. After a description of the ALICE experiment focused on its heavy flavour related performance, the status of the first analysis on charm production, measured by reconstructing the decays of D0, D+, D*+, and Ds into hadronic and semi-leptonic channels will be presented. An outlook of the same measurements for the upcoming Pb-Pb run will also be discussed.

scholarly journals Overview of hard hadron production results in ALICE

2019 ◽  
Vol 222 ◽  
pp. 01003
Author(s):  
Dmitri Peresunko
Keyword(s):  
Quark Gluon Plasma ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Hadron Production ◽  
Dense Medium ◽  
Parton Energy Loss ◽  
Alice Experiment ◽  
Ion Collisions ◽  
Hot Matter ◽  
Ultrarelativistic Heavy Ion Collisions

The ALICE experiment is designed to study the properties the hot and dense medium, the Quark-Gluon Plasma (QGP), produced in ultrarelativistic heavy-ion collisions at the LHC. Measuring production of hadrons with large Q2 transfer in these collisions provides the possibility to explore one of the most spectacular effects — the in-medium parton energy loss. By varying the observables among light and heavy flavored hadrons and fully reconstructed jets and by changing the colliding systems from pp to p–Pb and Pb–Pb, one can explore the transport properties of hot matter in great details. Here an overview of recent ALICE results on high-pT hadron and jet production in pp, p-A and A-A collisions at LHC energies is presented.

scholarly journals Low-mass dielectrons in pp, p–Pb and Pb–Pb collisions measured by the ALICE Experiment

2018 ◽  
Vol 171 ◽  
pp. 18011 ◽  
Author(s):  
Ivan Vorobyev
Keyword(s):  
Invariant Mass Distribution ◽  
Black Body ◽  
Heavy Ion ◽  
Black Body Radiation ◽  
Relativistic Heavy Ion Collisions ◽  
Vector Mesons ◽  
Alice Experiment ◽  
Final State ◽  
Correlated Electron ◽  
Ion Collisions

Dielectrons produced in ultra-relativistic heavy-ion collisions at the LHC provide a unique probe of the system evolution as they are unperturbed by final-state interactions. The dielectron continuum is extremely rich in physics sources: on top of ordinary Dalitz and resonance decays of pseudoscalar and vector mesons, thermal black-body radiation is of particular interest as it carries information about the temperature of the hot and dense system created in such collisions. The dielectron invariant-mass distribution is furthermore sensitive to medium modifications of the spectral function of short-lived vector mesons that are linked to the potential restoration of chiral symmetry at high temperatures. Correlated electron pairs from semi-leptonic charm and beauty decays provide complementary information about the heavy-quark energy loss.

scholarly journals (Anti-)(hyper-)nuclei production in Pb–Pb collisions with ALICE at the Large Hadron Collider

2020 ◽  
Vol 1643 (1) ◽  
pp. 012017
Author(s):  
Stefano Trogolo
Keyword(s):  
Hadron Collider ◽  
System Size ◽  
Heavy Ion ◽  
Particle Identification ◽  
Relativistic Heavy Ion Collisions ◽  
Particle Multiplicity ◽  
Charged Particle Multiplicity ◽  
Alice Experiment ◽  
Ion Collisions ◽  
Theoretical Predictions

Abstract In ultra-relativistic heavy-ion collisions a great variety of (anti-)(hyper-)nuclei are produced, namely deuteron, triton, 3He, 4He, hypertriton ( Λ 3 H ) and their antiparticles. The ALICE experiment is the most suited to investigate the production of (hyper-)nuclei at the LHC, thanks to an excellent particle identification and low-material budget detectors. Recent results on (hyper-)nuclei production as a function of transverse momentum (pT) and charged particle multiplicity (dN ch/d η ) in Pb–Pb collisions are presented. The evolution of the production yields with the system size is also shown, via comparison to the results obtained in small collision systems, like pp and p–Pb. The results on the production of (hyper-)nuclei are also compared with the predictions based on a naive coalescence approach and the statistical hadronization models. Furthermore, the latest and currently most precise measurement of the hypertriton lifetime is presented. It is compared with results obtained by different experimental techniques and with theoretical predictions.

scholarly journals Heavy Flavored Jets with CMS

2018 ◽  
Vol 171 ◽  
pp. 18005
Author(s):  
Kurt Jung
Keyword(s):  
Energy Loss ◽  
Heavy Ion ◽  
Jet Quenching ◽  
Dense Medium ◽  
Bottom Quarks ◽  
Heavy Flavor ◽  
Jet Production ◽  
Nuclear Modification ◽  
Ion Collisions ◽  
Nuclear Modification Factors

The energy loss of jets in heavy-ion collisions is expected to depend on the mass and flavor of the initiating parton. Thus, measurements of jet quenching with tagged partons place powerful constraints on the thermodynamic and transport properties of the hot and dense medium. Furthermore, recent results that constrain the jet production mechanism will shed additional light on the contributions of leading and next-to-leading order heavy flavor jet production with regard to the global energy loss picture. To this end, we present recent results measuring spectra and nuclear modification factors of jets associated to charm and bottom quarks in both pPb and PbPb collisions, as well as measurements of dijet asymmetry of pairs of b-jets in PbPb collisions.

scholarly journals Heavy-ion physics with the ALICE experiment at the CERN Large Hadron Collider

2012 ◽  
Vol 370 (1961) ◽  
pp. 917-932 ◽  
Author(s):  
J. Schukraft
Keyword(s):  
Large Hadron Collider ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Alice Experiment ◽  
Proton Proton ◽  
Heavy Ion Physics ◽  
Cern Large Hadron Collider ◽  
Ion Collisions ◽  
And Performance

After close to 20 years of preparation, the dedicated heavy-ion experiment A Large Ion Collider Experiment (ALICE) took first data at the CERN Large Hadron Collider (LHC) accelerator with proton collisions at the end of 2009 and with lead nuclei at the end of 2010. After a short introduction into the physics of ultra-relativistic heavy-ion collisions, this article recalls the main design choices made for the detector and summarizes the initial operation and performance of ALICE. Physics results from this first year of operation concentrate on characterizing the global properties of typical, average collisions, both in proton–proton (pp) and nucleus–nucleus reactions, in the new energy regime of the LHC. The pp results differ, to a varying degree, from most quantum chromodynamics-inspired phenomenological models and provide the input needed to fine tune their parameters. First results from Pb–Pb are broadly consistent with expectations based on lower energy data, indicating that high-density matter created at the LHC, while much hotter and larger, still behaves like a very strongly interacting, almost perfect liquid.

CHARMONIUM PRODUCTION IN Pb–Pb COLLISIONS AT ALICE: FROM SUPPRESSION TO REGENERATION?

2013 ◽  
Vol 28 (21) ◽  
pp. 1330018 ◽  
Author(s):  
ENRICO SCOMPARIN
Keyword(s):  
Phase Transition ◽  
Cross Sections ◽  
Short Review ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Alice Experiment ◽  
Model Calculations ◽  
Ion Collisions ◽  
Quark Production ◽  
History Of

Heavy quarkonium states are considered as one of the key observables for the study of the phase transition from a system made of hadrons towards a Quark–Gluon Plasma (QGP). In the last 25 years, experiments at CERN and Brookhaven have studied collisions of heavy ions looking for a suppression of charmonia/bottomonia, considered as a signature of the phase transition. After an introduction to the main concepts behind these studies and a short review of the SPS and RHIC results, I will describe the results obtained in Pb – Pb collisions by the ALICE experiment at the LHC. The ALICE findings will be critically compared to those of lower energy experiments, to CMS results, and to model calculations. The large cross-sections for heavy-quark production at LHC energies are expected to induce a novel production mechanism for charmonia in heavy-ion collisions, related to a recombination of [Formula: see text] pairs along the history of the collision and/or at hadronization. The occurrence of such a process at the LHC will be discussed. Finally, prospects for future measurements will be shortly addressed.

scholarly journals Quarkonium measurements in heavy-ion collisions with the STAR experiment

2018 ◽  
Vol 171 ◽  
pp. 18015
Author(s):  
Xinjie Huang
Keyword(s):  
Transverse Momentum ◽  
Nuclear Matter ◽  
Heavy Ion Collisions ◽  
Theoretical Calculations ◽  
Heavy Ion ◽  
Matter Effects ◽  
Nuclear Modification ◽  
Ion Collisions ◽  
Star Experiment ◽  
Nuclear Modification Factors

In these proceedings, we present the latest measurements of J/ψ and ϒ by the STAR experiment. The J/ψ and ϒ production measured in p+p collisions provide new baselines for similar measurements in Au+Au collisions, while the measurements in p+Au collisions can help quantify the cold nuclear matter effects. The J/ψ υ2 is measured in both U+U and Au+Au collisions to place constraints on the amount of J/ψ arising from recombination of deconfined charm and anti-charm pairs. Furthermore, the nuclear modification factors for ground and excited ϒ states as a function of transverse momentum and centrality are presented, and compared to those measured at the LHC as well as to theoretical calculations.

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