Nuclear Theory·nucl-th

Thursday·June 18, 2026

7 papers—3 primary·4 cross-listed

01
Universality and variability of the heavy r-process element abundance pattern from a nonequilibrium approach
David Blaschke · Friedrich K. Röpke · Gerd Röpke
A striking feature in the observed chemical composition of the majority of stars is the universality of the relative abundances of the heavy elements, although some outliers exist. We demonstrate that a nonequilibrium freeze-out approach provides a natural way of accounting for the typical abundance pattern and its variation. Here, we use a phenomenological method to characterize the coarse-grained distribution of heavy $r$ -process elements in several astrophysical objects. The Lagrange parameters show only minor fluctuations when comparing different stars. Larger deviations are observed in stars with low metallicity. The variations in the Lagrange parameters for these stars are presented. The determination of the Lagrange parameters can be instrumental in identifying possible sources for the formation of heavy elements. In particular, density fluctuations are considered as a source for the production of heavy elements in the early Universe.
nucl-thastro-ph.SRFront.Astron.Space Sci.(2025)·1 citation
02
Vortex Nucleons as Partial-Wave Filters in Nucleon--Nucleon Scattering
Jinniu Hu · Ying Zhang · Hong Shen
We propose vortex nucleon scattering as an angular-momentum-resolved probe of nucleon--nucleon partial waves. Using the standard $L S J$ partial-wave $S$ matrix as input, we show that an on-axis vortex incident state with a fixed orbital angular-momentum projection $m_{L} = ℓ$ imposes the direct selection rule $L \geq ∣ ℓ ∣$ on the initial nucleon--nucleon partial waves. As a result, the initial $S$ wave is excluded for $ℓ = 1$ , while both the initial $S$ and $P$ waves are excluded for $ℓ = 2$ . The underlying phase shifts are not modified. Instead, the vortex external state changes how the ordinary partial waves are projected into the scattering amplitude. We further analyze off-axis scattering, where the displacement of the target from the vortex axis introduces Bessel-function weights and partially relaxes the on-axis selection rule. These results suggest that vortex nucleons can provide a new experimental handle on the partial-wave content of the strong nucleon--nucleon interaction.
nucl-th0 citations
03
Geometric structure of two-neutron halo nuclei from Efimov physics at the unitary limit
R. M. Francisco🇧🇷 · D. S. Rosa🇧🇷 · T. Frederico🇧🇷 · M. T. Yamashita🇧🇷
We investigate the geometric structure of two-neutron halo nuclei from the perspective of Efimov physics. Using the analytic three-body wave function obtained from the Faddeev equations in the unitary limit, we explore the connection between Efimov universality and the spatial configuration of these weakly bound systems. The internal geometry is quantified through probability densities, root-mean-square interparticle distances and characteristic opening angles, evaluated for different neutron-core mass ratios. Our results reveal a universal trend in the geometry of s-wave dominated halo nuclei, reflecting the universal correlations characteristic of the Efimov-like regime.
nucl-thFew Body Syst.(2026)·0 citations
04
First Measurement of the $K^{-}$ Escape Cross Section in the $^{12} C (K^{-}, p)$ Reaction
Fumiya Oura🇯🇵 · Yudai Ichikawa🇯🇵 · Junko Yamagata-Sekihara🇯🇵 · Jung Keun Ahn🇰🇷 · Sung Wook Choi🇰🇷 · Manami Fujita🇯🇵 · Takeshi Harada🇯🇵 · Shoichi Hasegawa🇯🇵 · Shuhei Hayakawa🇯🇵 · Kenneth Hicks🇺🇸 · Satoru Hirenzaki🇯🇵 · Sang Hoon Hwang and 23 other authors
We investigated the $K ˉ$ -nucleus interaction through the simultaneous measurement of the inclusive $^{12} C (K^{-}, p)$ and exclusive $K^{-}$ -escape $^{12} C (K^{-}, p K_{esc}^{-})$ reactions at $1.8$ GeV/ $c$ at J-PARC. The present measurement explicitly focuses on the $K^{-}$ escape process for the first time, successfully accomplishing a direct experimental determination of the imaginary part of the $K^{-}$ optical potential. The differential cross section for the $K^{-}$ -escape reaction was determined to be $436 \pm 6 (stat.) \pm 44 (syst.) μ b/sr$ . A simultaneous likelihood fit yielded real and imaginary potential strengths of $V_{0} = - 72_{- 5}^{+ 3} (stat.)_{- 8}^{+ 0} (syst.) MeV$ and $W_{0} = - 100_{- 1}^{+ 7} (stat.)_{- 16}^{+ 0} (syst.) MeV$ at the nuclear center, respectively. The derived $W_{0}$ is significantly stronger than that predicted by theoretical models based on one-nucleon processes, suggesting possible contribution of multi-nucleon involving processes.
↳ nucl-exnucl-th0 citations
05
The electromagnetic decay of $^{250 m}$ No and the stability of neutron deficient Rf isotopes
A. Lopez-Martens🇫🇷 · K. Hauschild🇫🇷 · R. Chakma🇺🇸 · O. Dorvaux🇷🇺 · B. Gall🇷🇺 · K. Kessaci🇫🇷 · M.L. Chelnokov🇫🇷 · V.I. Chepigin🇷🇺 · A.V. Isaev🇷🇺 · I.N. Izosimov🇷🇺 · D.E. Katrasev🇫🇷 · A.A. Kuznetsova🇷🇺 and 7 other authors
The electromagnetic decay of the $\approx$ 40 $μ$ s isomer of $^{250}$ No has been investigated using the \textsc{Geant4} toolkit for the simulations of the interaction of particles through matter. It is concluded that the decay does not follow the pattern established in the lighter isotones, where the isomer decays directly to members of the ground state rotational band. An alternative scenario is proposed. The implications on the location of the isotopic border for neutron deficient Rf isotopes are discussed.
↳ nucl-exnucl-thEPJA(2026)·1 citation
06
Diffractive Production of Heavy Quarkonia at the Electron Ion Collider
Mohammad Yousuf Jamal🇨🇳 · Ajaharul Islam🇨🇳 · Aritra Bandyopadhyay🇵🇱 · Santosh K. Das🇮🇳
We study diffractive photo- and electroproduction of the $S$ -wave heavy quarkonia $J / ψ$ , $ψ (2 S)$ , and $Υ (n S)$ at energies relevant for the Electron-Ion Collider (EIC). The production amplitude is evaluated while retaining the full transverse-momentum ( $ℓ_{t}$ ) dependence of the hard two-gluon kernel, that is, without expanding the impact-parameter Bessel kernel as is done in the small-size color-dipole limit. The quarkonia light-cone wave functions are built from Cornell-potential solutions of the Schrödinger equation, normalized to the measured leptonic widths, and combined with a modern collinear gluon distribution. After benchmarking the framework against the full set of HERA charmonium cross-section ratio data, we provide a consistent set of bottomonium cross-section ratio predictions in EIC kinematics. We find that the full $ℓ_{t}$ -resolved treatment systematically improves the description of the radially excited states relative to the leading dipole limit, and we identify the kinematic windows where this difference is largest.
↳ hep-phhep-thnucl-thPRD(2026)·0 citations
07
Three-body unitary determination of the $f_{1} (1285)$ and $f_{1} (1420)$ pole positions
Tao-Ran Hu🇨🇳 · Hai-Long Fu🇩🇪 · Feng-Kun Guo🇨🇳 · Ulf-G. Meißner🇩🇪 · Xu Zhang🇨🇳
We study the $I^{G} (J^{P C}) = 0^{+} (1^{++})$ $K K ˉ π$ system in an infinite-volume three-body unitary framework, focusing on the pole content of the region of the $f_{1} (1285)$ and $f_{1} (1420)$ resonances. The coupled $π a_{0}$ - $K K ˉ^{*}$ amplitude is constructed in the spectator-isobar representation, where the one-particle-exchange interaction required by three-body unitarity automatically incorporates the triangle-singularity mechanism. The short-range three-body interaction is constrained by fitting the $0^{+} (1^{++})$ component of the BESIII $K_{S}^{0} K_{S}^{0} π^{0}$ invariant-mass distribution in the $J / ψ \to γ (K_{S}^{0} K_{S}^{0} π^{0})$ decay. Analytically continuing the fitted amplitude to the relevant unphysical Riemann sheets, we find two robust poles: \begin{align} \sqrt{s_{f_1(1285)}}&= \left(1277\pm2\pm1\right) -i\left(12\pm1\pm0\right)\text{MeV}\,,\notag\\ \sqrt{s_{f_1(1420)}}&= \left(1435\pm2\pm7\right) -i\left(40\pm2\pm1\right)\text{MeV}\,.\notag \end{align} The pole trajectories indicate that the $f_{1} (1285)$ originates from dressing a bare state introduced in the potential. In contrast, the $f_{1} (1420)$ is predominantly dynamically generated, and a single-channel analysis traces it to an $S$ -wave $K K ˉ^{*}$ quasi-bound state mixed with the nearby bare state, supporting its hadronic-molecule interpretation. We also find an additional pole deeper in the complex plane in the best-fit amplitude on the same Riemann sheet as the $f_{1} (1285)$ . This additional pole is generated by the $P$ -wave $π a_{0}$ contact interaction alone. It has a sizable cutoff and two-body-input dependence, and leaves little visible imprint on the physical lineshape. Finally, we provide a detailed and pedagogical appendix on how three-body cuts affect the solution of the integral equation.
↳ hep-phhep-exhep-latnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Universality and variability of the heavy r-process element abundance pattern from a nonequilibrium approach

Vortex Nucleons as Partial-Wave Filters in Nucleon--Nucleon Scattering

Geometric structure of two-neutron halo nuclei from Efimov physics at the unitary limit

First Measurement of the K− Escape Cross Section in the 12C(K−,p) Reaction

The electromagnetic decay of 250mNo and the stability of neutron deficient Rf isotopes

Diffractive Production of Heavy Quarkonia at the Electron Ion Collider

Three-body unitary determination of the f1​(1285) and f1​(1420) pole positions

Affiliations

First Measurement of the $K^{-}$ Escape Cross Section in the $^{12} C (K^{-}, p)$ Reaction

The electromagnetic decay of $^{250 m}$ No and the stability of neutron deficient Rf isotopes

Three-body unitary determination of the $f_{1} (1285)$ and $f_{1} (1420)$ pole positions