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21 pages, 439 KiB

Open AccessArticle

Exploring the Interpretations of Charmonia and cc

\bar{c} \bar{c}

Tetraquarks in the Relativistic Flux Tube Model

by Wen-Chao Dong, Zhi-Gang Wang and Jian-Wen Zhou

Symmetry 2025, 17(6), 931; https://doi.org/10.3390/sym17060931 - 11 Jun 2025

Viewed by 321

Abstract

Incited by the scant understanding of unsettled charmonia and newly observed

c c \bar{c} \bar{c}

tetraquarks, this work aims to explore the canonical interpretations and spectroscopic properties of these fully hidden-charm states. In the framework of a relativistic flux tube model, [...] Read more.

Incited by the scant understanding of unsettled charmonia and newly observed

c c \bar{c} \bar{c}

n L

-wave states with

1 \leq n + L \leq 4

are unraveled. In order to pin down the complete mass spectra, the hyperfine splittings induced by the spin-dependent interactions are incorporated into the final predictions. Accordingly, fourteen charmonia are well identified, including the

η_{c} (1 S)

J / ψ (1 S)

χ_{c 0} (1 P)

h_{c} (1 P)

χ_{c 1} (1 P)

χ_{c 2} (1 P)

η_{c} (2 S)

ψ (2 S)

ψ (3770)

ψ_{2} (3823)

ψ_{3} (3842)

χ_{c 0} (3915)

χ_{c 2} (3930)

, and

ψ (4040)

states. Additionally, the exotic

T_{ψ ψ} (6400)

T_{ψ ψ} (6600)

T_{ψ ψ} (6900)

, and

T_{ψ ψ} (7300)

states are interpreted as the

1 S

-wave,

1 P / 2 S

-wave,

1 D / 2 P

-wave, and

2 D / 3 P / 4 S

-wave

c c \bar{c} \bar{c}

tetraquarks, respectively. Based on the achieved outcomes, the spin-parity quantum number is imperative to discriminate the nature of the

c c \bar{c} \bar{c}

structures, pending further experimental measurement in the future. Full article

(This article belongs to the Special Issue Symmetry in Hadron Physics)

21 pages, 1039 KiB

Open AccessArticle

Charmonium Transport in Heavy-Ion Collisions at the LHC

by Biaogang Wu and Ralf Rapp

Universe 2024, 10(6), 244; https://doi.org/10.3390/universe10060244 - 31 May 2024

Cited by 6 | Viewed by 1168

Abstract

We provide an update on our semi-classical transport approach for quarkonium production in high-energy heavy-ion collisions, focusing on

J / ψ

and

ψ (2 S)

mesons in 5.02 TeV Pb-Pb collisions at the Large Hadron Collider (LHC) at both forward and [...] Read more.

We provide an update on our semi-classical transport approach for quarkonium production in high-energy heavy-ion collisions, focusing on

J / ψ

and

ψ (2 S)

mesons in 5.02 TeV Pb-Pb collisions at the Large Hadron Collider (LHC) at both forward and mid-rapidity. In particular, we employ the most recent charm-production cross sections reported in pp collisions, which are pivotal for the magnitude of the regeneration contribution, and their modifications due to cold-nuclear-matter (CNM) effects. Multi-differential observables are calculated in terms of nuclear modification factors as a function of centrality, transverse momentum, and rapidity, including the contributions from feeddown from bottom hadron decays. For our predictions for

ψ (2 S)

production, the mechanism of sequential regeneration relative to the more strongly bound

J / ψ

meson plays an important role in interpreting recent ALICE data. Full article

(This article belongs to the Special Issue Universe: Feature Papers 2024—High Energy Nuclear and Particle Physics)

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14 pages, 840 KiB

Open AccessArticle

Measurements of J/ψ Production vs. Event Multiplicity in Forward Rapidity in p + p Collisions in the PHENIX Experiment

by Zhaozhong Shi

Universe 2023, 9(7), 322; https://doi.org/10.3390/universe9070322 - 4 Jul 2023

Cited by 2 | Viewed by 1386

Abstract

J / ψ

, a charmonium bound state made of a charm and an anti-charm quark, was discovered in the 1970s and confirmed the quark model. Because the mass of charm quarks is significantly above the quantum chromodynamics (QCD) scale [...] Read more.

J / ψ

Λ_{Q C D}

, charmonia are considered excellent probes to test perturbative quantum chromodynamics (pQCD) calculations. In recent decades, they have been studied extensively at different high-energy colliders. However, their production mechanisms, which involve multiple scales, are still not very well understood. Recently, in high-multiplicity

p + p

collisions at RHIC and at the LHC, a significant enhancement of

J / ψ

production yield has been observed, which suggests a strong contribution of multi-parton interaction (MPI). This is different from the traditional pQCD picture, where charm quark pairs are produced from a single hard scattering between partons in

p + p

collisions. In this work, we will report the

J / ψ

normalized production yield as a function of normalized charged particle multiplicity over a board range of rapidity and event multiplicity in the

J / ψ \to μ^{+} μ^{-}

channel with PHENIX Run 15

p + p

data at

\sqrt{s} = 200

GeV. The results are compared with PYTHIA 8 simulations with the MPI option turned on and off. Finally, the outlooks of

J / ψ

p + A u

and

A u + p

collisions, along with color glass condensate (CGC) predictions and the multiplicity-dependent

ψ (2 S) / J / ψ

ratio in

p + p

data, will be briefly discussed. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

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