528 research outputs found
Dynamics of Hot QCD Matter -- Current Status and Developments
Get PDFThe discovery and characterization of hot and dense QCD matter, known as
Quark Gluon Plasma (QGP), remains the most international collaborative effort
and synergy between theorists and experimentalists in modern nuclear physics to
date. The experimentalists around the world not only collect an unprecedented
amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider
(RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large
Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these
data to unravel the mystery of this new phase of matter that filled a few
microseconds old universe, just after the Big Bang. In the meantime,
advancements in theoretical works and computing capability extend our wisdom
about the hot-dense QCD matter and its dynamics through mathematical equations.
The exchange of ideas between experimentalists and theoreticians is crucial for
the progress of our knowledge. The motivation of this first conference named
"HOT QCD Matter 2022" is to bring the community together to have a discourse on
this topic. In this article, there are 36 sections discussing various topics in
the field of relativistic heavy-ion collisions and related phenomena that cover
a snapshot of the current experimental observations and theoretical progress.
This article begins with the theoretical overview of relativistic
spin-hydrodynamics in the presence of the external magnetic field, followed by
the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an
overview of experiment results.Comment: Compilation of the contributions (148 pages) as presented in the `Hot
QCD Matter 2022 conference', held from May 12 to 14, 2022, jointly organized
by IIT Goa & Goa University, Goa, Indi
Abstracts of 1st International Conference on Machine Intelligence and System Sciences
Get PDFThis book contains the abstracts of the papers presented at the International Conference on Machine Intelligence and System Sciences (MISS-2021) Organized by the Techno College of Engineering, Agartala, Tripura, India & Tongmyong University, Busan, South Korea, held on 1–2 November 2021. This conference was intended to enable researchers to build connections between different digital technologies based on Machine Intelligence, Image Processing, and the Internet of Things (IoT).
Conference Title: 1st International Conference on Machine Intelligence and System SciencesConference Acronym: MISS-2021Conference Date: 1–2 November 2021Conference Location: Techno College of Engineering Agartala, Tripura(w), IndiaConference Organizer: Techno College of Engineering, Agartala, Tripura, India & Tongmyong University, Busan, South Korea
Measurement of the angle between jet axes in Pb-Pb collisions at TeV$
No full textThis letter presents the first measurement of the angle between different jet axes (denoted as ) in PbPb collisions. The measurement is carried out in the 010% most-central events at TeV. Jets are assembled by clustering charged particles at midrapidity using the anti- algorithm with resolution parameters and and transverse momenta in the intervals GeV/ and GeV/, respectively. Measurements at these low transverse momenta enhance the sensitivity to quarkgluon plasma (QGP) effects. A comparison to models implementing various mechanisms of jet energy loss in the QGP shows that the observed narrowing of the PbPb distribution relative to pp can be explained if quark-initiated jets are more likely to emerge from the medium than gluon-initiated jets. These new measurements discard intra-jet broadening as described in a model calculation with the BDMPS formalism as the main mechanism of energy loss in the QGP. The data are sensitive to the angular scale at which the QGP can resolve two independent splittings, favoring mechanisms that incorporate incoherent energy loss.This letter presents the first measurement of the angle between different jet axes (denoted as ) in PbPb collisions. The measurement is carried out in the 010% most-central events at TeV. Jets are assembled by clustering charged particles at midrapidity using the anti- algorithm with resolution parameters and and transverse momenta in the intervals GeV/ and GeV/, respectively. Measurements at these low transverse momenta enhance the sensitivity to quarkgluon plasma (QGP) effects. A comparison to models implementing various mechanisms of jet energy loss in the QGP shows that the observed narrowing of the PbPb distribution relative to pp can be explained if quark-initiated jets are more likely to emerge from the medium than gluon-initiated jets. These new measurements discard intra-jet broadening as described in a model calculation with the BDMPS formalism as the main mechanism of energy loss in the QGP. The data are sensitive to the angular scale at which the QGP can resolve two independent splittings, favoring mechanisms that incorporate incoherent energy loss
Azimuthal anisotropy of jet particles in p-Pb and Pb-Pb collisions at = 5.02 TeV
Get PDFThe azimuthal anisotropy of particles associated with jets (jet particles) at midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at TeV down to transverse momentum () of 0.5 GeV/ and 2 GeV/, respectively, with ALICE. The second-order Fourier coefficient of the jet-particle azimuthal distribution () in high-multiplicity p-Pb collisions is positive, with a significance reaching 6.8 at low . Comparisons with the inclusive charged-particle and with AMPT calculations are discussed. The model describes qualitatively the main features of the jet-particle in high-multiplicity p-Pb collisions and indicates that the positive jet-particle is generated by parton interactions.The azimuthal anisotropy of particles associated with jets (jet particles) at midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at = 5.02 TeV down to transverse momentum (p) of 0.5 GeV/c and 2 GeV/c, respectively, with ALICE. The results obtained in p-Pb collisions are based on a novel three-particle correlation technique. The azimuthal anisotropy coefficient v in high-multiplicity p-Pb collisions is positive, with a significance reaching 6.8σ at low p, and its magnitude is smaller than in semicentral Pb-Pb collisions. In contrast to the measurements in Pb-Pb collisions, the v coefficient is also found independent of p within uncertainties. Comparisons with the inclusive charged-particle v and with AMPT calculations are discussed. The predictions suggest that parton interactions play an important role in generating a non-zero jet-particle v in p-Pb collisions, even though they overestimate the reported measurement. These observations shed new insights on the understanding of the origin of the collective behaviour of jet particles in small systems such as p-Pb collisions, and provide significant stringent new constraints to models.[graphic not available: see fulltext]The azimuthal anisotropy of particles associated with jets (jet particles) at midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at = 5.02 TeV down to transverse momentum () of 0.5 GeV/ and 2 GeV/, respectively, with ALICE. The results obtained in p-Pb collisions are based on a novel three-particle correlation technique. The azimuthal anisotropy coefficient in high-multiplicity p-Pb collisions is positive, with a significance reaching 6.8 at low , and its magnitude is smaller than in semicentral Pb-Pb collisions. In contrast to the measurements in Pb-Pb collisions, the coefficient is also found independent of within uncertainties. Comparisons with the inclusive charged-particle and with AMPT calculations are discussed. The predictions suggest that parton interactions play an important role in generating a non-zero jet-particle in p-Pb collisions, even though they overestimate the reported measurement. These observations shed new insights on the understanding of the origin of the collective behaviour of jet particles in small systems such as p-Pb collisions, and provide significant stringent new constraints to models
Measurement of the angle between jet axes in PbPb collisions at TeV
No full textInternational audienceThis letter presents the first measurement of the angle between different jet axes (denoted as ) in PbPb collisions. The measurement is carried out in the 010% most-central events at TeV. Jets are assembled by clustering charged particles at midrapidity using the anti- algorithm with resolution parameters and and transverse momenta in the intervals GeV/ and GeV/, respectively. Measurements at these low transverse momenta enhance the sensitivity to quarkgluon plasma (QGP) effects. A comparison to models implementing various mechanisms of jet energy loss in the QGP shows that the observed narrowing of the PbPb distribution relative to pp can be explained if quark-initiated jets are more likely to emerge from the medium than gluon-initiated jets. These new measurements discard intra-jet broadening as described in a model calculation with the BDMPS formalism as the main mechanism of energy loss in the QGP. The data are sensitive to the angular scale at which the QGP can resolve two independent splittings, favoring mechanisms that incorporate incoherent energy loss
First polarisation measurement of coherently photoproduced J/ in ultra-peripheral PbPb collisions at TeV
No full textThe first measurement of the polarisation of coherently photoproduced J/ mesons in ultra-peripheral PbPb collisions, using data at TeV , is presented. The J/ meson is measured via its dimuon decay channel in the forward rapidity interval -4.0 J/ψ mesons in ultra-peripheral Pb–Pb collisions, using data at sNN=5.02 TeV, is presented. The J/ψ meson is measured via its dimuon decay channel in the forward rapidity interval −4.0<y<−2.5 using the ALICE detector at the CERN LHC. An event sample corresponding to an integrated luminosity of 750 μb−1 ± 5% (syst) is analysed. Hadronic activity is highly suppressed since the interaction is mediated by a photon. The polar and azimuthal angle distributions of the decay muons are measured, and the polarisation parameters λθ, λφ, λθφ are extracted. The analysis is carried out in the helicity frame. The results are found to be consistent with a transversely polarised J/ψ. These values are compared with previous measurements by the H1 and ZEUS experiments. The polarisation parameters of coherent J/ψ photoproduction in Pb–Pb collisions are found to be consistent with the s-channel helicity conservation hypothesis.The first measurement of the polarisation of coherently photoproduced J/\psi\sqrt{s_{\rm NN}}\psi-4.0 < y < -2.5\mu\text{b}^{-1}\pm\mathbf{\lambda_{\theta}}\mathbf{\lambda_{\varphi}}\mathbf{\lambda_{\theta\varphi}}\psi\psis$-channel helicity conservation hypothesis
Measurement of the angle between jet axes in PbPb collisions at TeV
No full textInternational audienceThis letter presents the first measurement of the angle between different jet axes (denoted as ) in PbPb collisions. The measurement is carried out in the 010% most-central events at TeV. Jets are assembled by clustering charged particles at midrapidity using the anti- algorithm with resolution parameters and and transverse momenta in the intervals GeV/ and GeV/, respectively. Measurements at these low transverse momenta enhance the sensitivity to quarkgluon plasma (QGP) effects. A comparison to models implementing various mechanisms of jet energy loss in the QGP shows that the observed narrowing of the PbPb distribution relative to pp can be explained if quark-initiated jets are more likely to emerge from the medium than gluon-initiated jets. These new measurements discard intra-jet broadening as described in a model calculation with the BDMPS formalism as the main mechanism of energy loss in the QGP. The data are sensitive to the angular scale at which the QGP can resolve two independent splittings, favoring mechanisms that incorporate incoherent energy loss
Measurement of the angle between jet axes in PbPb collisions at TeV
No full textThis letter presents the first measurement of the angle between different jet axes (denoted as ) in PbPb collisions. The measurement is carried out in the 010% most-central events at TeV. Jets are assembled by clustering charged particles at midrapidity using the anti- algorithm with resolution parameters and and transverse momenta in the intervals 40 < p_{\rm T}^{\rm ch jet} < 140 GeV/ and 80 < p_{\rm T}^{\rm ch jet} < 140 GeV/, respectively. Measurements at these low transverse momenta enhance the sensitivity to quarkgluon plasma (QGP) effects. A comparison to models implementing various mechanisms of jet energy loss in the QGP shows that the observed narrowing of the PbPb distribution relative to pp can be explained if quark-initiated jets are more likely to emerge from the medium than gluon-initiated jets. These new measurements discard intra-jet broadening as described in a model calculation with the BDMPS formalism as the main mechanism of energy loss in the QGP. The data are sensitive to the angular scale at which the QGP can resolve two independent splittings, favoring mechanisms that incorporate incoherent energy loss
ALICE upgrades during the LHC Long Shutdown 2
No full textA Large Ion Collider Experiment (ALICE) has been conceivedand constructed as a heavy-ion experiment at the LHC. During LHCRuns 1 and 2, it has produced a wide range of physics results usingall collision systems available at the LHC. In order to bestexploit new physics opportunities opening up with the upgraded LHCand new detector technologies, the experiment has undergone a majorupgrade during the LHC Long Shutdown 2 (2019–2022). This comprisesthe move to continuous readout, the complete overhaul of coredetectors, as well as a new online event processing farm with aredesigned online-offline software framework. These improvementswill allow to record Pb-Pb collisions at rates up to 50 kHz, whileensuring sensitivity for signals without a triggerable signature
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