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Radial profile of heavy quarks in jets in high-energy nuclear collisions

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Sa Wang, Wei Dai, Ben-Wei Zhang, Enke Wang

Nuclear Theory · Submitted 29 Sep 2020 · 19 references

Pith's verdict: A short proceedings that extends an existing MC framework to predict opposite radial modifications for charm and bottom in jets; the charm side is validated against CMS, but the bottom prediction rests on an unvalidated p+p baseline and an in-preparation reference.

T0 · AI review

How this review was made: An AI referee (deepseek-v4-flash) read the paper on August 27, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

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  2. T1 Audit Automatic checks that the references and files the paper relies on exist and match.
  3. T2 Compute The paper's code or calculations re-run with the same results.
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  5. T4 Proof Those claims proved, and the proof checked by computer.

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arXiv ID2009.13959 (version 1)
Pith IDR7K3TCS4, Pith's permanent record of this paper and its review
CitationBen-Wei Zhang, Enke Wang, Sa Wang, Wei Dai. "Radial profile of heavy quarks in jets in high-energy nuclear collisions." arXiv:2009.13959 (2020). https://pith.science/paper/R7K3TCS4
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The paper

The paper claims

This paper predicts a mass-dependent reversal of jet quenching inside quark-gluon plasma: charm quarks diffuse to larger radius while bottom quarks stay closer to the jet axis.

The reading

The paper tries to establish that the radial profile of heavy quarks inside jets is a mass-sensitive probe of the quark-gluon plasma. Its simulation, combining collisional drag and random kicks with medium-induced gluon radiation, reproduces the measured $D^0$-meson radial distribution in jets in both p+p and Pb+Pb collisions at 5.02 TeV. The paper then predicts a reversal between the two heavy flavors: charm quarks diffuse to larger radius from the jet axis, while bottom quarks concentrate nearer the axis. If correct, this gives a direct observable consequence of the mass dependence of parton energy loss.

What carries the argument

The mechanism is a Monte Carlo transport model of heavy quarks moving through an expanding hydrodynamic medium. Heavy-quark momenta evolve under drag, random kicks, and recoil from emitted gluons; the gluon emission spectrum is the higher-twist form with a dead-cone factor that suppresses radiation from massive quarks. The initial hard events come from a next-to-leading-order plus parton-shower generator, heavy quarks are hadronized with fragmentation functions, and the drag and diffusion coefficients are tied by the fluctuation-dissipation relation to lattice-QCD input. The observable is the normalized radial profile of identified heavy-flavor hadrons in jets reconstructed with the anti-$k_T$ algorithm.

Extended reading notes

Core claim

The central claim is that jet quenching modifies the angular distribution of charm and bottom quarks inside a jet in opposite directions in central Pb+Pb collisions. For charm quarks with transverse momentum between 4 and 20 GeV, the in-medium interaction suppresses the distribution near the jet axis and enhances it at larger angular distance $r=\sqrt{(\Delta\phi_{JD})^2+(\Delta\eta_{JD})^2}$, whereas for bottom quarks in the same range the distribution shifts toward the axis. The paper reports good agreement with the measured $D^0$-in-jet radial profile, and presents this flavor reversal as a prediction of the same framework, attributing it mainly to the different initial p+p distributions of charm and bottom.

Load-bearing premise

The load-bearing premise is that the p+p radial distribution of bottom quarks at low $p_T$, which is not checked against any bottom-tagged jet measurement, is accurate enough to serve as the baseline for the predicted opposite Pb+Pb modification.

Editorial extensions

If this is right

  • If the prediction holds, the $D^0$-in-jet radial profile in Pb+Pb is explained by random kicks plus gluon recoil, not by a new fragmentation effect.
  • Bottom-tagged jets should show a qualitatively different pattern from charm-tagged jets in Pb+Pb, providing an unambiguous mass-dependence test.
  • The modification should be largest at low $p_T$ and nearly vanish above 20 GeV, so the effect has a built-in kinematic control.
  • The same framework can be used to predict radial profiles for other identified hadrons in jets, such as $D_s$ or $\Lambda_c$, without retuning.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the predicted reversal is confirmed, radial-profile ratios (PbPb/pp) could become a sharper mass scan than single-hadron nuclear modification factors.
  • The same initial-distribution mechanism suggests that other heavy-flavor mesons with different fragmentation functions will show pattern variations, not just charm versus bottom.
  • A natural next step is to extend the calculation to larger jet radii, where the outward diffusion of charm should appear as an enhanced tail.
Original abstract

In high energy nuclear collisions, heavy flavor tagged jets are useful hard probes to study the properties of the quark-gluon plasma (QGP). In this talk, we present the first theoretical prediction of the $D^0$ meson radial distributions in jets relative to the jet axis both in p+p and Pb+Pb collisions at $5.02$ TeV, it shows a nice agreement with the available experimental data. The in-medium jet evolution in the study is described by a Monte Carlo transport model which has been incorporated with the initial events as input provided by the next-to-leading order (NLO) plus parton shower (PS) event generator SHERPA. In such evolution process, both elastic and inelastic parton energy loss in the hot and dense medium are taken into account. Within this same simulation framework, we predict different modification patterns of the radial profile of charm and bottom quarks in jets in Pb+Pb collisions: jet quenching effect will lead the charm quarks diffuse to lager radius while lead the bottom quarks distributed closer to jet axis.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 4,460 input tokens.

What the abstract itself states, as probabilities: claims first 0.93 · states limitation 0.08 · human participants 0.01 · controlled comparison 0.53 · randomized assignment 0.01 · states quantitative result 0.27 · compares with prior results 0.86 · mentions code or data availability 0.03.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

In high energy nuclear collisions, heavy flavor tagged jets are useful hard probes to study the properties of the quark-gluon plasma (QGP). In this talk, we present the first theoretical prediction of the $D^0$ meson radial distributions in jets relative to the jet axis both in p+p and Pb+Pb collisions at $5.02$ TeV, it shows a nice agreement with the available experimental data. The in-medium jet evolution in the study is described by a Monte Carlo transport model which has been incorporated with the initial events as input provided by the next-to-leading order (NLO) plus parton shower (PS) event generator SHERPA. In such evolution process, both elastic and inelastic parton energy loss in the hot and dense medium are taken into account. Within this same simulation framework, we predict different modification patterns of the radial profile of charm and bottom quarks in jets in Pb+Pb collisions: jet quenching effect will lead the charm quarks diffuse to lager radius while lead the bottom quarks distributed closer to jet axis.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 In high energy nuclear collisions, heavy flavor tagged jets are useful hard probes to study the properties of the quark-gluon plasma (QGP). background 1.00 0.05 0.03 asserted 0.98
s1 In this talk, we present the first theoretical prediction of the $D^0$ meson radial distributions in jets relative to the jet axis both in p+p and Pb+Pb collisions at $5.02$ TeV, it shows a nice agreement with the available experimental data. contribution 0.82 0.93 0.47 asserted 0.99
s2 The in-medium jet evolution in the study is described by a Monte Carlo transport model which has been incorporated with the initial events as input provided by the next-to-leading order (NLO) plus parton shower (PS) event generator SHERPA. method 1.00 0.63 0.03 asserted 0.99
s3 In such evolution process, both elastic and inelastic parton energy loss in the hot and dense medium are taken into account. method 1.00 0.57 0.03 asserted 1.00
s4 Within this same simulation framework, we predict different modification patterns of the radial profile of charm and bottom quarks in jets in Pb+Pb collisions: jet quenching effect will lead the charm quarks diffuse to lager radius while lead the bottom quarks distributed closer to jet axis. result 0.98 0.92 0.73 asserted 0.89

What kind of paper the classifier reports this is: simulation study 0.91 · evidence from simulation or computation 1.00.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. (Color online) The normalized radial distributions of D 0 meson in jets as a function of the angular distance from the jet axis in p+p collisions at 5.02 TeV provided by SHERPA are compared with CMS data at (a) 4 GeV < p D T < 20 GeV and (b) p D T > 20 GeV. 0. 0 0. 1 0. 2 0. 3 1 0 -1 1 0 0 1 0 1 1 0 2 r CMS p+p CMS Pb+Pb Th eory p+p Th eory Pb+Pb 4 GeV < p D T < 20 GeV D 0 - jet 1 / N J D d N J D / d r 0 -1 00% cen tral i ty
Figure 2. (Color online) Radial distribution of D 0 meson in jets in p+p and Pb+Pb collisions at two pT range: (a) 4 GeV < p D T < 20 GeV and (b) p D T > 20 GeV are compared with the CMS measurements [2]. where x and k⊥ are the energy fraction and transverse momentum carried by the radiated gluon, the last quadruplicate term denote dead-cone effect of massive heavy quarks. ˆq is the jet transport parameter extracted from a global fitting of single hadron production in A+A collisions [16]. Since Langevin treatment is not suitable for the massless light partons, we used the results of pQCD…
Figure 3. (Color online) Radial distributions of charm and bottom quarks in jets in p+p collisions for three p Q T ranges: (a) p Q T < 20 GeV, (b) 20 GeV < p Q T < 40 GeV, and (c) 40 GeV < p Q T < 60 GeV. 0 1 2 3 4 5 6 7 8 0. 00 0. 05 0. 1 0 0. 1 5 0. 20 0. 25 0. 30 0. 6 0. 8 1 . 0 1 . 2 1 . 4 5. 02 TeV an ti -kT R=0. 3 | η jet | <2. 0 p jet T > 60 GeV Ch arm p+p Ch arm P b+P b 1 / N d N / d r 4 < p Q T < 20 GeV cen tral i ty: 0-1 0% r a ti o: P b P b / p p r (a) 0 1 2 3 4 5 6 7 8 0. 00 0. 05 0. 1 0 0. 1 5 0. 20 0. 25 0. 30 0. 6 0. 8 1 . 0 1 . 2 1 . 4 4 < p Q T < 20 GeV cen tral i ty: 0-1 0%…
Figure 4. (Color online) Radial distributions of charm (a) and bottom (b) quarks in jets in p+p and 0−10% Pb+Pb collisions at √ sNN = 5.02 TeV, for the p Q T range : 4 GeV < p Q T < 20 GeV, the ratios (PbPb/pp) have also been shown in the lower panels to quantify the medium modification. profile of D 0 meson in jets at two kinematic regions( 4 GeV< p D T < 20 GeV and p D T > 20 GeV) both in p+p and Pb+Pb collisions at 5.02 TeV. At 4 < p D T < 20 GeV, suppression near jet axis and enhancement at larger radius indicates that charm quarks diffuse farther away from the jet axis due to the…

Figures reproduced from arXiv:2009.13959 by the authors.

References
How the literature uses it

1 arXiv paper cite this in 1 sentence

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

What it cites · 3 sentences without a confident label

Uses the method or tool of 5 papers
  • We use the modified Langevin equations incorporating with a recoil term to describe the heavy quark propagation [ref] , [equation] where drag coefficient $Γ$ and diffusion coefficient $κ$ are related by the so called fluctuation-dissipation relation $κ=2ETΓ$ and their values are determined by the Lattice QCD calculation [ref] .

    Heavy quark dynamics and hadronization in ultra-relativistic heavy-ion collisions: collisional versus radiative energy loss · p+p baseline and in-medium parton energy loss · 0.99

  • We use the modified Langevin equations incorporating with a recoil term to describe the heavy quark propagation [ref] , [equation] where drag coefficient $Γ$ and diffusion coefficient $κ$ are related by the so called fluctuation-dissipation relation $κ=2ETΓ$ and their values are determined by the Lattice QCD calculation [ref] .

    A non-perturbative estimate of the heavy quark momentum diffusion coefficient · p+p baseline and in-medium parton energy loss · 0.99

  • We use the modified Langevin equations incorporating with a recoil term to describe the heavy quark propagation [ref] , [equation] where drag coefficient $Γ$ and diffusion coefficient $κ$ are related by the so called fluctuation-dissipation relation $κ=2ETΓ$ and their values are determined by the Lattice QCD calculation [ref] .

    Transverse Momentum Balance and Angular Distribution of $b\bar{b}$ Dijets in Pb+Pb collisions · p+p baseline and in-medium parton energy loss · 0.99

Compares with 1 paper
Cites as support 2 papers
  • This diffusion effect can be interpreted by two mechanisms: the random kicks by medium constituents in Brown motion and the momentum recoil by medium-induced gluon radiation, especially at lower charm quark $p_T$ ($<$5 GeV) the former plays a critical role [ref] .

    Radial distribution of charm quarks in jets in high-energy heavy-ion collisions · Results and discussions · 0.97

  • This diffusion effect can be interpreted by two mechanisms: the random kicks by medium constituents in Brown motion and the momentum recoil by medium-induced gluon radiation, especially at lower charm quark $p_T$ ($<$5 GeV) the former plays a critical role [ref] .

    Diffusion of charm quarks in jets in high-energy heavy-ion collisions · Results and discussions · 0.97

Discussion

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