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27 pages, 627 KB

Open AccessReview

Heavy-Flavour Jets in High-Energy Nuclear Collisions

by Sa Wang, Wei Dai, Enke Wang, Xin-Nian Wang and Ben-Wei Zhang

Symmetry 2023, 15(3), 727; https://doi.org/10.3390/sym15030727 - 15 Mar 2023

Cited by 16 | Viewed by 3801

Reconstructed jets initiated from heavy quarks provide a powerful tool to probe the properties of the quark–gluon plasma (QGP) and to explore the mass hierarchy of jet quenching. In this article, we review the recent theoretical progresses on heavy-flavour jets in high-energy nuclear collisions at the RHIC and LHC. We focus on the yields and substructures of charm and bottom quark jets with jet-quenching effects, such as the nuclear modification factors, transverse momentum imbalance, angular correlation, radial profiles, fragmentation functions, the “dead-cone” effect, etc. Full article

(This article belongs to the Special Issue Heavy-Ion Collisions and Multiparticle Production)

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13 pages, 1393 KB

Open AccessReview

Machine Learning Applications for Jet Tagging in the CMS Experiment

by Antimo Cagnotta, Francesco Carnevali and Agostino De Iorio

Appl. Sci. 2022, 12(20), 10574; https://doi.org/10.3390/app122010574 - 19 Oct 2022

Cited by 11 | Viewed by 5956

Abstract

The fundamental physics research at the frontier accessible by today’s particle accelerators such as the CERN Large Hadron Collider pose unique challenges in terms of complexity and abundance of data to analyse. In this context, it is of paramount importance to develop algorithms capable of dealing with multivariate problems to enhance humans’ ability to interpret data and ultimately increase the discovery potential of the experiments. Machine learning techniques therefore assume an increasingly important role in the experiments at the LHC. In this work, we give an overview of the latest developments in this field, with a particular focus on the algorithms developed and used within the CMS Collaboration. The review follows this structure: (1) Introduction presents the CMS Experiment at LHC and the most common methods used in particle physics; (2) Jet Flavour Tagging briefly describes the main algorithms used to reconstruct heavy-flavour jets; (3) Jet Substructure and Deep Tagging focuses on the identification of heavy-particle decay in boosted jets; (4) Analysis Applications gives examples of applying the algorithm in physics analyses; and (5) Conclusions summarises the state-of-the-art and gives indications for future studies. Full article

(This article belongs to the Special Issue Machine Learning Applications in Atlas and CMS Experiments at LHC)

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10 pages, 382 KB

Open AccessArticle

Defining the Underlying-Event Activity in the Presence of Heavy-Flavour Processes in Proton-Proton Collisions at LHC Energies

by László Gyulai, Szende Sándor and Róbert Vértesi

Particles 2022, 5(3), 235-244; https://doi.org/10.3390/particles5030021 - 7 Jul 2022

Viewed by 2605

Abstract

We present a systematic analysis of heavy-flavour production in the underlying event in connection to a leading hard process in pp collisions at

\sqrt{s} = 13

TeV, using the PYTHIA 8 Monte Carlo event generator. We compare results from events selected by triggering [...] Read more.

We present a systematic analysis of heavy-flavour production in the underlying event in connection to a leading hard process in pp collisions at

\sqrt{s} = 13

TeV, using the PYTHIA 8 Monte Carlo event generator. We compare results from events selected by triggering on the leading hadron, as well as those triggered with reconstructed jets. We show that the kinematics of heavy-flavour fragmentation complicates the characterisation of the underlying event, and the usual method which uses the leading charged final-state hadron as a trigger may wash away the connection between the leading process and the heavy-flavour particle created in association with that. Events triggered with light or heavy-flavour jets, however, retain this connection and bring more direct information on the underlying heavy-flavour production process, but may also import unwanted sensitivity to gluon radiation. The methods outlined in the current work provide means to verify model calculations for light and heavy-flavour production in the jet and the underlying event in great details. Full article

(This article belongs to the Special Issue 2022 Feature Papers by Particles’ Editorial Board Members)

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5 pages, 301 KB

Open AccessProceeding Paper

Study of in-Medium Energy Loss with Heavy-Flavour Correlations in pp and Pb-Pb Collisions with ALICE at the LHC

by Samrangy Sadhu

Proceedings 2019, 10(1), 43; https://doi.org/10.3390/proceedings2019010043 - 29 Apr 2019

Viewed by 1580

Abstract

The azimuthal correlations between heavy-flavour hadrons or heavy-flavour decay electrons with charged particles in Pb-Pb collisions give insight on the modification of charm-jet properties in nucleus-nucleus collisions and the mechanisms through which heavy quarks in-medium energy-loss takes place. Studies in pp collisions, besides constituting the necessary baseline for nucleus-nucleus measurements, are important for testing expectations from pQCD-inspired Monte Carlo generators. In ALICE heavy-flavour hadrons are studied via their fully reconstructed hadronic decays (D mesons and

Λ_{c}

baryon), via semileptonic decays of charmed baryons (

Λ_{c}

Ξ_{c}

) and via leptons coming from heavy-flavour hadron decays. In particular in the central barrel,

η < | 0.8 |

, the electrons from heavy-flavour hadron decays are investigated. This proceeding will include the study of azimuthal correlations of D mesons with charged particles in pp collisions and heavy-flavour decay electrons with charged particles in pp and Pb-Pb collisions at different energies available at the LHC. The Experimental results will also be compared with the expectations from POWHEG and PYTHIA event generators. Full article

(This article belongs to the Proceedings of Hot Quarks 2018—Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions)

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5 pages, 1746 KB

Open AccessProceeding Paper

Multiplicity Dependence of Heavy-Flavour Correlations with Charged Particle and Collective Effects in p–Pb Collisions at √s_NN = 5.02 TeV with ALICE at LHC

by Marianna Mazzilli

Proceedings 2019, 10(1), 20; https://doi.org/10.3390/proceedings2019010020 - 12 Apr 2019

Viewed by 1599

Abstract

Azimuthal correlation studies of heavy-flavour particles with charged particles in p–Pb collisions can give an insight into the cold nuclear matter effects on heavy-quark production and hadronization into heavy-flavour jets. Multiplicity-dependent measurements of angular correlations of heavy-flavour particles with charged hadrons allow us to investigate the collective behavior of the system and the initial state effects on heavy flavour hadron production. In addition, they can reveal possible modifications of the heavy-quark fragmentation and hadronization at different multiplicities. We present ALICE measurements of azimuthal correlations of prompt D-mesons with charged hadrons as a function of the multiplicity in p–Pb collisions at

\sqrt{s_{NN}}

= 5.02TeV. Moreover, the elliptic flow (

v_{2}

) of heavy-flavour hadron decay electrons in high-multiplicity p–Pb collisions at

\sqrt{s_{NN}}

= 5.02 TeV, obtained using correlations with charged particles, is reported. Full article

(This article belongs to the Proceedings of Hot Quarks 2018—Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions)

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