Nuclear Theory·nucl-th

Friday·December 12, 2025

10 papers—4 primary·6 cross-listed

05
[Submitted on 10 Dec 2025] (cross-list from hep-ph)
Living on the edge: radius effects in the angular substructure of heavy-ion jets
Carlota Andres🇫🇷 · Jack Holguin🇬🇧 · Benjamin Kimelman🇺🇸 · Raghav Kunnawalkam Elayavalli🇺🇸 · Jussi Viinikainen🇺🇸 · Zhong Yang🇺🇸
Jet substructure observables serve as essential tools for probing the quark-gluon plasma produced in relativistic heavy-ion collisions. Their interpretation, however, is often complicated by edge effects, which arise when correlated particles fall outside the reconstructed jet radius, introducing distortions that obscure the underlying QCD dynamics. In this work, we present a comprehensive phenomenological study of edge effects in soft-insensitive angular observables, taking the two-point energy correlator (EEC) as a representative example. We argue that these distortions scale linearly with the average angular separation between the winner-take-all and $E$ -scheme axes $⟨ ϕ ⟩$ , and validate this behavior across proton-proton (p-p) simulations with Pythia8 and Herwig7, as well as lead-lead (Pb-Pb) simulations using JEWEL and CoLBT. In p-p collisions, edge effects are strongly suppressed, scaling as $(R_{L} / R)^{4}$ , whereas medium-modified jets can exhibit larger distortions, with contributions scaling as $(R_{L} / R)^{2}$ and $(R_{L} / R)^{4}$ . Taking Pb-Pb/p-p ratios of the EEC substantially reduces, but does not completely eliminate, these distortions, highlighting the need of accounting for edge effects in the interpretation of heavy-ion jet substructure measurements. Since edge effects are largely governed by the $⟨ ϕ ⟩$ distribution, studying this distribution provides a new handle for benchmarking and constraining the modeling of edge effects in heavy-ion event generators.
Comments:
14 pages, 12 edgy figures, plus 2 appendices with 3 more equally edgy figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2512.10026 [pdf]
4 citations
06
[Submitted on 10 Dec 2025] (cross-list from hep-ph)
Unpolarized GPDs at small $x$ and non-zero skewness
Yuri V. Kovchegov🇺🇸 · M. Gabriel Santiago🇺🇸 · Huachen Sun🇺🇸
We study the small- $x$ asymptotics of unpolarized generalized parton distributions (GPDs) and generalized transverse momentum distributions (GTMDs). Unlike the previous works in the literature, we consider the case of non-zero (but small) skewness while allowing for non-linear contributions to the evolution equations. We show that unpolarized GPDs and GTMDs at small $x$ are related to the eikonal dipole amplitude $N$ , whose small- $x$ evolution is given by the BK/JIMWLK evolution equations, and to the odderon amplitude $O$ , whose evolution is also known in the literature. We show that the effect of non-zero skewness $ξ \neq = 0$ is to modify the value of the evolution parameter (rapidity) in the arguments for the dipole amplitudes $N$ and $O$ from $Y = ln (1/ x)$ to $Y = ln min {1/∣ x ∣, 1/∣ ξ ∣}$ .
Comments:
12 pages, 2 figures; typos corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2512.10086 [pdf]
PLB(2026)·9 citations
07
[Submitted on 11 Dec 2025] (cross-list from hep-ph)
A unified approach for the hadronic weak decays of $Λ$ and $Σ^{\pm} \to N π$
Ye Cao🇨🇳 · Ming-Xiao Duan🇨🇳 · Zhong Tao🇨🇳 · Qiang Zhao🇨🇳
We provide a unified approach for the two-body hadronic weak decays of hyperons with $S = - 1$ , i.e. $Λ$ and $Σ^{\pm}$ , in the framework of the non-relativistic constitute quark model (NRCQM). A combined analysis shows that the branching ratios and asymmetry parameters of the decay channels $Λ \to p π^{-}$ and $Σ^{\pm} \to N π$ can be well described in the same framework with the direct pion emission, color suppressed internal $W$ emission, and pole terms included. However, the channel $Λ \to n π^{0}$ indicates significant deviations from the experimental data based on these mentioned transition mechanism. We demonstrate that the final state interactions (FSIs) via the coupled-channel rescatterings play a crucial role in $Λ \to n π^{0}$ . Namely, the dominant decay channel of $Λ \to p π^{-}$ can contribute to $Λ \to n π^{0}$ via the $p π^{-} \to n π^{0}$ rescatterings. This is a leading correction effect for $Λ \to n π^{0}$ at the one-loop level. We find that such FSIs only become the leading effects in $Λ \to n π^{0}$ , but contribute as subleading contributions in other channels. We also demonstrate that the pole terms are indispensable in these hyperon decays. In particular, for $Σ^{-} \to n π^{-}$ and $Σ^{+} \to n π^{+}$ , it shows that $Λ (1405)$ as the intermediate state in the pole term amplitude is necessary for reproducing the experimental data. We also find that a dynamic selection rule forbids the radial excitation state $N (1710)$ of the quark model multiplet $∣70,^{2} 8, 2, 0^{+}, 1/ 2^{+} ⟩$ from contribution. To some extent, the hyperon hadronic weak decays serve as a special probe for the underlying transition mechanisms and can provide some constraints on the intermediate $J^{P} = 1/ 2^{\pm}$ baryon resonances.
Comments:
Revtex, 35 pages, 6 Figures, 19 Tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2512.10346 [pdf]
2 citations
08
[Submitted on 11 Dec 2025] (cross-list from hep-ph)
Three-body resonances of $α α M$ clusters ( $M = ϕ$ , $J / ψ$ , $η_{c}$ ) in $_{M}^{8} Be$ nuclei
Hao Zhou🇨🇳 · Xiang Liu🇨🇳
Motivated by the recently obtained HAL QCD potentials for the $N$ - $ϕ$ , $N$ - $J / ψ$ , and $N$ - $η_{c}$ interactions, we investigate the structure of the exotic nuclei $_{ϕ}^{8} Be$ , $_{J / ψ}^{8} Be$ , and $_{η_{c}}^{8} Be$ as $α + α + M$ three-body systems ( $M$ denotes the meson). The bound and resonant states are calculated consistently using the Gaussian expansion method, with resonances identified via the complex scaling method. For the $α ϕ$ and $α$ -charmonium interactions, a folding potential is constructed based on the HAL QCD potentials and fitted to a Woods-Saxon form. We find that the $ϕ$ meson exhibits a strong ``glue-like" effect, binding the $0_{1}^{+}$ , $2_{1}^{+}$ , and $4_{1}^{+}$ resonant states of $^{8}$ Be into stable states and significantly reducing the $α$ - $α$ distance. In contrast, the interactions of $J / ψ$ and $η_{c}$ with the nucleus are weaker, forming only shallow bound states with the $0_{1}^{+}$ state of $^{8}$ Be and even increasing the $α$ - $α$ separation. Notably, our analysis predicts weakly bound $α$ - $J / ψ$ states in the $^{4} S_{3/2}$ and $^{2} S_{1/2}$ channels, a result not reported in prior studies, which suggests that $_{J / ψ}^{8} Be$ may not be a Borromean nucleus. The sensitivity of the $_{M}^{8} Be (4_{1}^{+})$ state-transitioning from bound to resonant depending on the $α$ -particle radius-highlights the subtle dynamics at play. These results provide a systematic theoretical comparison of how different vector mesons modify nuclear clustering, offering critical predictions for future experimental searches of such exotic hadron-nucleus systems.
Comments:
11 pages, 6 figures and 4 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2512.10695 [pdf]
PRD(2026)·2 citations
09
[Submitted on 11 Dec 2025] (cross-list from hep-ph)
Disperon QED
Yizhou Fang🇨🇭 · Sophie Kollatzsch🇨🇭 · Marco Rocco🇮🇹 · Adrian Signer🇨🇭 · Yannick Ulrich🇬🇧 · Max Zoller🇨🇭
We present disperon QED, a method to deal with data input in loop processes in Monte Carlo codes. It relies on dispersion relations, automated tools such as OpenLoops, effective field theory methods and a threshold subtraction. We motivate this method and apply it to the process $ee \to π π$ in McMule to deal with hadronic vacuum polarisation insertions in two-loop contributions as well as the vector form factor of the pion within the form-factor scalar QED approximation. The generality of this method for more complicated processes is emphasised.
Comments:
34 pages, 8 figures, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2512.10709 [pdf]
SciPost Phys.(2026)·9 citations
10
[Submitted on 11 Dec 2025] (cross-list from hep-lat)
Equation of state, QCD phase diagram: predictions from lattice QCD
Bastian B. Brandt🇩🇪
I review recent results on phase structure and equation of state of strong interaction matter from lattice QCD. Particular emphasis is given to the axes where direct simulations are possible and results are obtained with sufficient control over systematic effects. I also discuss the status of approaching the region of non-zero baryochemical potentials using indirect methods.
Comments:
6 pages, invited plenary talk at Quark Matter 2025, Frankfurt am Main, Germany, April 6-12 2025
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2512.10760 [pdf]
EPJ Web Conf.(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Living on the edge: radius effects in the angular substructure of heavy-ion jets

Unpolarized GPDs at small x and non-zero skewness

A unified approach for the hadronic weak decays of Λ and Σ±→Nπ

Three-body resonances of ααM clusters (M=ϕ, J/ψ, ηc​) in M8​Be nuclei

Disperon QED

Equation of state, QCD phase diagram: predictions from lattice QCD

Affiliations

Unpolarized GPDs at small $x$ and non-zero skewness

A unified approach for the hadronic weak decays of $Λ$ and $Σ^{\pm} \to N π$

Three-body resonances of $α α M$ clusters ( $M = ϕ$ , $J / ψ$ , $η_{c}$ ) in $_{M}^{8} Be$ nuclei