scholarly journals Vector boson tagged jets and jet substructure

2018 ◽  
Vol 172 ◽  
pp. 05006
Author(s):  
Ivan Vitev
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion Collisions ◽  
Vector Boson ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Jet Substructure ◽  
Proton Proton ◽  
Jet Production ◽  
Ion Collisions ◽  
Jet Shapes

In these proceedings, we report on recent results related to vector boson-tagged jet production in heavy ion collisions and the related modification of jet substructure, such as jet shapes and jet momentum sharing distributions. Z0-tagging and γ-tagging of jets provides new opportunities to study parton shower formation and propagation in the quark-gluon plasma and has been argued to provide tight constrains on the energy loss of reconstructed jets. We present theoretical predictions for isolated photon-tagged and electroweak boson-tagged jet production in Pb+Pb collisions at √sNN = 5.02 TeV at the LHC, addressing the modification of their transverse momentum and transverse momentum imbalance distributions. Comparison to recent ATLAS and CMS experimental measurements is performed that can shed light on the medium-induced radiative corrections and energy dissipation due to collisional processes of predominantly quark-initiated jets. The modification of parton splitting functions in the QGP further implies that the substructure of jets in heavy ion collisions may differ significantly from the corresponding substructure in proton-proton collisions. Two such observables and the implication of tagging on their evaluation is also discussed.

JET CONVERSIONS IN QGP AND SUPPRESSION OF IDENTIFIED HADRONS

2007 ◽  
Vol 16 (07n08) ◽  
pp. 1930-1936 ◽  
Author(s):  
WEI LIU ◽  
CHE MING KO ◽  
BEN-WEI ZHANG
Keyword(s):  
Transverse Momentum ◽  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
High Transverse Momentum ◽  
Ion Collisions ◽  
Conversion Rates ◽  
Gluon Jets

A gluon or quark jet traversing through a quark-gluon plasma can be converted into a quark or gluon jet through scatterings with thermal partons. Their conversion rates due to two-body elastic and inelastic scattering as well as scatterings involving gluon radiation are evaluated in the lowest order in Quantum Chromodynamics (QCD). Including both energy loss and conversions of quark and gluon jets in the expanding quark-gluon plasma produced in relativistic heavy ion collisions, we find a net conversion of quark jets to gluon jets. This reduces the difference between the nuclear modification factors for quark and gluon jets in central heavy ion collisions and thus enhances the p/π+ and [Formula: see text] ratios at high transverse momentum. Using the larger QCD coupling constant from lattice QCD calculations than that given by the perturbative QCD further enhances the net quark to gluon jet conversion rate, leading to a closer similarity between these ratios at high transverse momentum in central Au + Au collisions at [Formula: see text] and in p + p collisions at same energy as observed in experiments.

scholarly journals JET RESULTS AND JET RECONSTRUCTION TECHNIQUES IN p+p AND THEIR PROSPECTS IN HEAVY-ION COLLISIONS IN ATLAS

2011 ◽  
Vol 20 (07) ◽  
pp. 1545-1550
Author(s):  
◽  
MARTIN SPOUSTA
Keyword(s):  
Cross Sections ◽  
Heavy Ion Collisions ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Ion Collisions ◽  
Expected Performance ◽  
Jet Shapes ◽  
Jet Cross Sections

We present the measurement of jet production performed with the ATLAS detector in proton-proton collisions at center-of-mass energy of 7 TeV, using an integrated luminosity of 17 nb−1. We show the inclusive jet cross sections and jet shapes. The expected performance and strategy for the jet reconstruction in heavy ion collisions is also discussed.

scholarly journals Jets in Heavy Ion Collisions with the ATLAS Detector

2018 ◽  
Vol 46 ◽  
pp. 1860020
Author(s):  
Helena Santos
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion Collisions ◽  
Statistical Significance ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Dense Medium ◽  
Momentum Balance ◽  
Ion Collisions ◽  
High Statistical Significance ◽  
Wide Range

Jets constitute a golden probe to study the quark gluon plasma produced in heavy ion collisions at the LHC. Being produced at the early stages of the collisions, they are expected to be modified as propagating through the hot and dense medium. A signature of the modification is the energy loss lowering the jet yields at a given transverse momentum. A factor of two suppression is observed in central Pb+Pb collisions with respect to [Formula: see text] collisions. Other signatures are the modification of the dijet momentum balance and the modification of fragmentation functions. These proceedings describe results on these observables from ATLAS in Runs 1 and 2. The high statistical significance of these data samples collected by ATLAS allows precision measurements of these observables in a wide range of transverse momentum and centrality.

scholarly journals The Rapidity Distributions and the Thermalization Induced Transverse Momentum Distributions in Au-Au Collisions at RHIC Energies

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Zhi-Jin Jiang ◽  
Jia-Qi Hui ◽  
Yu Zhang
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion Collisions ◽  
Good Description ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Ion Collisions ◽  
Hadronic State ◽  
Momentum Distributions ◽  
Rapidity Distributions ◽  
Made In

It is widely believed that the quark-gluon plasma (QGP) might be formed in the current heavy ion collisions. It is also widely recognized that the relativistic hydrodynamics is one of the best tools for describing the process of expansion and hadronization of QGP. In this paper, by taking into account the effects of thermalization, a hydrodynamic model including phase transition from QGP state to hadronic state is used to analyze the rapidity and transverse momentum distributions of identified charged particles produced in heavy ion collisions. A comparison is made between the theoretical results and experimental data. The theoretical model gives a good description of the corresponding measurements made in Au-Au collisions at RHIC energies.

scholarly journals First measurements of N-subjettiness in central Pb-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ = 2.76 TeV

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
◽  
S. Acharya ◽  
D. Adamová ◽  
A. Adler ◽  
J. Adolfsson ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Jet Substructure ◽  
Centre Of Mass ◽  
Pp Collisions ◽  
Coincidence Technique ◽  
Inclusive Jets ◽  
Ion Collisions ◽  
Using Data

Abstract The ALICE Collaboration reports the first fully-corrected measurements of the N-subjettiness observable for track-based jets in heavy-ion collisions. This study is performed using data recorded in pp and Pb-Pb collisions at centre-of-mass energies of $$ \sqrt{s} $$ s = 7 TeV and $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 2.76 TeV, respectively. In particular the ratio of 2-subjettiness to 1-subjettiness, τ2/τ1, which is sensitive to the rate of two-pronged jet substructure, is presented. Energy loss of jets traversing the strongly interacting medium in heavy-ion collisions is expected to change the rate of two-pronged substructure relative to vacuum. The results are presented for jets with a resolution parameter of R = 0.4 and charged jet transverse momentum of 40 ≤ pT,jet ≤ 60 GeV/c, which constitute a larger jet resolution and lower jet transverse momentum interval than previous measurements in heavy-ion collisions. This has been achieved by utilising a semi-inclusive hadron-jet coincidence technique to suppress the larger jet combinatorial background in this kinematic region. No significant modification of the τ2/τ1 observable for track-based jets in Pb-Pb collisions is observed relative to vacuum PYTHIA6 and PYTHIA8 references at the same collision energy. The measurements of τ2/τ1, together with the splitting aperture angle ∆R, are also performed in pp collisions at $$ \sqrt{s} $$ s = 7 TeV for inclusive jets. These results are compared with PYTHIA calculations at $$ \sqrt{s} $$ s = 7 TeV, in order to validate the model as a vacuum reference for the Pb-Pb centre-of-mass energy. The PYTHIA references for τ2/τ1 are shifted to larger values compared to the measurement in pp collisions. This hints at a reduction in the rate of two-pronged jets in Pb-Pb collisions compared to pp collisions.

scholarly journals Azimuthal dependence of two-particle transverse momentum current correlations

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Niseem Magdy ◽  
Sumit Basu ◽  
Victor Gonzalez ◽  
Ana Marin ◽  
Olga Evdokimov ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion Collisions ◽  
Theoretical Models ◽  
Energy System ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Entropy Density ◽  
Relativistic Heavy Ion Collisions ◽  
Azimuthal Dependence ◽  
Ion Collisions

AbstractTwo-particle transverse momentum correlation functions are a powerful technique for understanding the dynamics of relativistic heavy-ion collisions. Among these, the transverse momentum correlator $$G_{2}\left( \varDelta \eta ,\varDelta \varphi \right) $$ G 2 Δ η , Δ φ is of particular interest for its potential sensitivity to the shear viscosity per unit of entropy density $$\eta /s$$ η / s of the quark-gluon plasma formed in heavy-ion collisions. We use the UrQMD, AMPT, and EPOS models for Au–Au at $$\sqrt{s_\mathrm{NN}}$$ s NN = 200 GeV and Pb–Pb at $$\sqrt{s_\mathrm{NN}}$$ s NN = 2760 GeV to investigate the long range azimuthal dependence of $$G_{2}\left( \varDelta \eta ,\varDelta \varphi \right) $$ G 2 Δ η , Δ φ , and explore its utility to constrain $$\eta /s$$ η / s based on charged particle correlations. We find that the three models yield quantitatively distinct transverse momentum Fourier harmonics coefficients $$a^{p_\mathrm{T}}_{n}$$ a n p T . We also observe these coefficients exhibit a significant dependence on $$\eta /s$$ η / s in the context of the AMPT model. These observations suggest that exhaustive measurements of the dependence of $$G_{2}\left( \varDelta \varphi \right) $$ G 2 Δ φ with collision energy, system size, collision centrality, in particular, offer the potential to distinguish between different theoretical models and their underlying assumptions. Exhaustive analyses of $$G_{2}\left( \varDelta \varphi \right) $$ G 2 Δ φ obtained in large and small systems should also be instrumental in establishing new constraints for precise extraction of $$\eta /s$$ η / s .

scholarly journals Jet charge in heavy-ion collisions

2020 ◽  
Vol 235 ◽  
pp. 05004
Author(s):  
Hai Tao Li
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Jet Quenching ◽  
Effective Theory ◽  
Proton Proton ◽  
Ion Collisions ◽  
Soft Collinear Effective Theory ◽  
Flavor Tagging ◽  
Proton Proton Collisions

Jet quenching effects have been widely used to study the properties of strongly-interacting matter, quark-gluon plasma, in heavy-ion collisions. Flavor tagging in heavy-ion collisions plays an important role to reveal the medium parton showers for quark and gluon evolution. Combining with kinematic information, the average jet charge can be used to separate the contribution of different jet flavors, which is defined as the momentum- weighted sum of the charges of hadrons inside a given jet. Using soft-collinear effective theory with medium interactions, we investigate the factorization of the jet charge in QCD medium. We provide predictions for jet charge distributions and their modifications compared to the ones in proton-proton collisions.

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