Nuclear Theory·nucl-th

Fri·Sep 11, 2026Friday·September 11, 2026

10 papers—5 primary·5 cross-listed

01
Fission Modes and Fragment Shell Structures in $^{258}$ Md $^{*}$ from Six-Dimensional Langevin Calculations
K. Okada · K. Nishio · T. Wada · N. Carjan
The fission of $^{258}$ Md $^{*}$ is calculated in the excitation energy range of $E^{*} = 6$ --36 MeV using a six-dimensional Langevin equation. The calculated events are classified into two symmetric and two asymmetric fission modes based on the fragment mass and the quadrupole deformations of the two fragments at scission. The symmetric modes are separated by their total kinetic energies into the short (high TKE) and superlong (low TKE) modes, whereas the asymmetric modes differ in mass asymmetry. With increasing excitation energy, the yield of the short mode decreases, whereas the combined yield of the two asymmetric modes increases, as observed in the in-beam prompt-fission study of $^{258}$ Md $^{*}$ . From an analysis of the fragment shapes and associated single-particle levels, the short mode and the dominant asymmetric mode with the smaller mass asymmetry are found to involve a compact fragment characterized by deformed shell gaps at $Z = 52$ and $N = 84$ , while the complementary fragments have different quadrupole deformations in the two modes.
nucl-th
02
Classification of fission modes in $^{236}$ U using a six-dimensional Langevin approach
K. Okada · K. Nishio · T. Wada · N. Carjan
Thermal neutron-induced fission of $^{235}$ U is studied using a six-dimensional Langevin approach based on the Cassini shape parametrization. Scission events are classified into Asymmetric 1 (AS1), Asymmetric 2 (AS2), and Superlong (SL) fission modes by applying the $k$ -means algorithm to the fragment mass and the quadrupole deformations of both fragments. For each mode, proton and neutron single-particle levels are calculated for representative fragments to examine their shell structures. The AS1 heavy fragment exhibits proton gaps at $Z = 50$ and 52 and neutron gaps at $N = 82$ and 84, whereas well-developed gaps appear at $Z = 56$ and $N = 88$ in the AS2 heavy fragment. The mass splits of AS1 and AS2 are close to those of the conventional Standard I and Standard II modes, respectively. However, the average total kinetic energy is lower for AS1 than for AS2, opposite to the conventional ordering of Standard I and Standard II. This reversal reflects the more elongated shape of the AS1 light fragment. The SL mode is conventionally interpreted in terms of macroscopic liquid-drop effects, whereas the pronounced proton shell gap at $Z = 46$ suggests that proton shell effects also contribute to the elongated symmetric configuration. The classification based on fragment mass and the quadrupole deformations of both fragments provides a basis for distinguishing fission modes and examining the corresponding fragment shell structures at scission.
nucl-th
03
Gogny interaction from beginnings to current challenges
Nathalie Pillet · Geoffrey Zietek · Luis Robledo · Marc Dupuis · Tomas R. Rodriguez
The main goal of the present review article is to gather for the first time various facets of the phenomenological effective Gogny interaction which was originally proposed in the 70's. This involves both nuclear phenomena of interest that led to its creation and evolution as well as highly technical aspects that led the objectives to be achieved. With this in mind, we propose a discussion structured around four points. After a general introduction, the history and philosophy of the Gogny interaction is exposed. In particular, one highlights an intuitive way of guiding the determination of the parameters of the phenomenological interaction with the results obtained from a realistic interaction using Hartree-Fock calculations and second order corrections and a G-matrix. One also shows that physical phenomena such as pairing or fission were essential to improve the parameterization. The evolution of the original analytical form over the years is also discussed. The second point concern the emulator that was used for the generation of parameterizations. Its modifications, consistent with the evolution of the analytical form, are given. Other fitting procedures, more recent, are also evoked. The third key point is dedicated to the role of the nuclear matter in the fitting process and the acceptance of a parameterization. The objective of the last key point is to highlight some results obtained with the Gogny interaction in nuclear structure, fission and reactions that have allowed to interpret experimental data.
nucl-th
04
From Superfluid Coherence to High- $K$ Fragment Channels at Nuclear Scission
M. Kowal · A. Augustyn · T. Cap · K. Pomorski
The origin of fission-fragment spin remains unresolved. For $^{236}$ U fission, we combine deformation-dependent finite-temperature pairing with a multidimensional scission-spectrum analysis. Near the pairing-quenching boundary, pair breaking exposes near-Fermi high- $Ω$ intruder orbitals and opens high- $K$ channels. The resulting maximum spectroscopic capacities range from a few to more than a dozen units of $ℏ$ . Rapid neck rupture acts as a non-adiabatic projection freeze-out, where pairing serves as a dynamical gate: its critical attenuation does not generate angular momentum but allows existing high- $K$ projections to be retained diabatically as local fragment- $K$ components while total angular momentum remains conserved.
nucl-th
05
Study of the multiplicity dependence of non-flow correlations in pp collisions at $s = 200$ GeV using PYTHIA
Milan Stojanovic · Joern Putschke
The observation of a near-side enhancement in long-range correlations within high-multiplicity pA and pp collisions, commonly referred to as the ridge, has motivated significant efforts to quantify possible collective effects in small systems. Estimation of non-flow contributions in two-particle correlation measurements in small systems at the LHC typically relies on the assumption that jet-induced non-flow correlations are independent of event multiplicity. Consequently, this assumption allows the high-multiplicity non-flow to be estimated and accounted for by directly using low-multiplicity events. In this paper, the validity of this assumption is studied examining the multiplicity dependence of non-flow contributions estimated via two-particle correlation functions in pp collisions at RHIC energies $s = 200$ ~GeV using the PYTHIA event generator. It is observed that selecting any specific multiplicity range inherently biases jet production dynamics. These biases introduce a non-trivial multiplicity dependence of the non-flow contribution at RHIC energies. The dependence of jet fragmentation and $p_{T}$ -differential cross sections on event multiplicity is studied using a variety of commonly used multiplicity estimators, including mid-rapidity charged-particle multiplicity, forward multiplicity, and underlying-event activity. The results indicate that non-flow contributions do not exhibit simple multiplicity scaling and challenge the applicability of standard subtraction procedures utilized at LHC energies at lower RHIC collision energies.
nucl-thnucl-ex
06
Computationally Efficient Description of Medium Response to Jets in Heavy Ion Collisions
Jorge Casalderrey-Solana · José Guilherme Milhano · Daniel Pablos · Krishna Rajagopal · Xiaojun Yao
We develop an Efficient Wake procedure for computing the distribution of hadrons originating from jet wakes in heavy ion collisions - the hydrodynamic response of a droplet of quark-gluon plasma to the energy and momentum deposited in it by high-energy partons propagating through it. The procedure employs the linearity of linearized hydrodynamics and takes account of the effects of both longitudinal expansion and transverse radial flow on the hydrodynamic evolution of the wakes and on the resulting particle production at the freezeout hypersurface. It makes repeated use of template solutions to linearized hydrodynamics in a Bjorken flow background with no transverse flow, templates that need only be computed once, and uses suitable rotations and boosts to map fluctuations from these templates to fluctuations at a point on the freezeout hypersurface in a way that incorporates the effects of the radial flow. We benchmark this procedure by comparing its results to results obtained from full $(3 + 1)$ -dimensional nonlinear hydrodynamics calculations, find reasonable agreement, and find that our Efficient Wake procedure yields a much better description of the distribution of hadrons originating from jet wakes than does the older oversimplified procedure employed in the Hybrid Model. And, the Efficient Wake procedure is computationally efficient: it is at least tens of thousands of times faster than full nonlinear hydrodynamics calculations. Hence, we anticipate that when our new procedure is implemented in Monte Carlo analyses of jets in heavy ion collisions, for example in the Hybrid Model, it will greatly improve the description of the soft component of many jet and jet substructure observables as compared to experimental data.
↳ hep-phnucl-th
07
A detailed view at magnetic dipole strengths: The case of semi-magic $^{50}$ Ti
B. Kelly · M. Spieker · U. Friman-Gayer · L. T. Baby · T. Beck · A. L. Conley · S. W. Finch · J. Isaak · Krishichayan · E. Litvinova · H. Pai · N. Pietralla and 5 other authors
Magnetic dipole, $M 1$ , strengths were studied in semi-magic $^{50}$ Ti up to the neutron-separation threshold by combining data from $(d, p)$ one-neutron transfer, $(γ, γ^{'})$ real-photon scattering, $(e, e^{'})$ inelastic scattering at extreme backward angles, and $(p, p^{'})$ at $E_{p} = 210$ MeV and extreme forward angles. The combination of all probes provided unique access to the neutron spin-flip contribution and the possibility to evaluate its role in generating the spin-flip $M 1$ strengths. The small contribution of the neutron $(1 f_{7/2})^{- 1} (1 f_{5/2})^{+ 1}$ spin-flip transitions, which were probed with the $(d, p)$ reaction, to the overall strength in $^{50}$ Ti questions the standard picture for the microscopic origin of spin-flip strength in the $f p$ shell. For $^{50}$ Ti, this letter shows that $J^{π} = 1^{+}$ states with larger neutron $(1 f_{7/2})^{- 1} (1 f_{5/2})^{+ 1}$ spectroscopic factors do not correspond to the ones with the largest $B (M 1; 0_{1}^{+} \to 1_{i}^{+})$ strengths.
↳ nucl-exnucl-thPhys. Rev. Lett. 136, 082502 (2026)
08
Properties of the positive and negative parity charm-strange and bottom-strange mesons $D_{s}$ , $D_{s}^{*}$ , $D_{s 0}^{*}$ , $D_{s 1}$ , $B_{s}$ , $B_{s}^{*}$ , $B_{s 0}^{*}$ , $B_{s 1}$ from lattice QCD: masses, decay constants, and compositeness
Forrest Guyton · Stefan Meinel
We present a lattice-QCD determination of properties of the lightest scalar, pseudoscalar, vector, and axial-vector heavy-strange mesons. This includes the decay constants of all mesons, and the binding energies and Weinberg compositeness parameters of the positive-parity states. The calculations are performed with domain-wall fermions for the light and strange quarks and anisotropic clover actions for the charm and bottom quarks. We use seven ensembles generated by RBC/UKQCD with pion masses ranging from 431 MeV to 139 MeV and lattice spacings ranging from 0.114 fm to 0.073 fm, which allows us to perform combined chiral and continuum extrapolations. For the negative-parity mesons, we obtain $f_{D_{s}} = 251.4 (2.1) (0.4) (2.5) MeV$ , $f_{D_{s}^{*}} = 272.5 (4.3) (1.0) (2.7) MeV$ , $f_{B_{s}} = 228.4 (5.8) (0.5) (2.3) MeV$ , $f_{B_{s}^{*}} = 229.2 (4.4) (0.8) (2.3) MeV$ , $f_{D_{s}^{*}} / f_{D_{s}} = 1.086 (14) (11)$ , and $f_{B_{s}^{*}} / f_{B_{s}} = 1.003 (22) (10)$ . In the positive-parity sector, the finite-volume energies and decay constants are extracted using the GEVP from correlation matrices with three different types of hadron interpolating operators, including operators with covariant derivatives and meson-meson-scattering operators at both source and sink. After extrapolation to the physical point, we obtain $f_{D_{s 0}^{*}} = 136.6 (8.0) (4.0) (1.4)$ MeV, $f_{D_{s 1}} = 200 (33) (24) (2)$ MeV, $f_{B_{s 0}^{*}} = 207 (12) (8) (2)$ MeV, and $f_{B_{s 1}} = 196 (16) (11) (2)$ MeV. Our results for $f_{B_{s 0}^{*}}$ and $f_{B_{s 1}}$ are the first from lattice QCD. Lüscher's method is used to find the infinite-volume bound-state masses. At the physical point, we obtain $m_{D_{s 0}^{*}} - m_{D} - m_{K} = - 48 (14) (4)$ MeV, $m_{D_{s 1}} - m_{D^{*}} - m_{K} = - 61 (15) (2)$ MeV, $m_{B_{s 0}^{*}} - m_{B} - m_{K} = - 69 (13) (4)$ MeV, and $m_{B_{s 1}} - m_{B^{*}} - m_{K} = - 77 (10) (5)$ MeV. Our analysis shows consistency with the positive-parity states being predominantly molecular.
↳ hep-lathep-exhep-phnucl-th
09
Qubit-Qutrit Quantum Tomography of hadronic $Λ ϕ$ and $Λ K^{* 0}$ systems
Veronica Kanachova · Feng Liu · Zhoudunming Tu
Quantum-information observables have emerged in recent years as new tools in nuclear and particle physics, from entanglement in top-quark pairs to spin correlations in $Λ Λ ˉ$ production. Extending these studies to unequal-spin hadronic final states poses a fundamental challenge: the $6 \times 6$ density matrix of a qubit-qutrit system contains 35 independent spin parameters, but the decays of $Λ V$ pairs, with $V = ϕ$ or $K^{* 0}$ , provide access to only 23 due to the hidden vector polarization from the strong decay. In this Letter, we formulate a qubit-qutrit quantum tomography (QQQT) technique for these spin- $\frac{1}{2} \otimes 1$ systems and establish exact criteria for entanglement certification from the \textit{incomplete} density matrix. Compared with the $Λ Λ ˉ$ system, QQQT of $Λ ϕ$ and $Λ K^{* 0}$ provides a new probe of nonperturbative QCD hadronization, enabling a direct comparison of the spin evolution of entangled quark pairs produced from the vacuum as they hadronize into a baryon or a vector meson.
↳ hep-phhep-exnucl-exnucl-th+1
10
Collinear fragmentation of pseudoscalar quarkonia from NLO NRQCD
Francesco Giovanni Celiberto · Francesca Lonigro
We discuss a new family of publicly available collinear fragmentation functions (FFs) for pseudoscalar quarkonia, the NRFF1.0 set. It builds upon the Heavy-Flavor Non-Relativistic evolution (HF-NRevo) scheme, designed to describe heavy-hadron formation through leading-power fragmentation at moderate and large transverse momentum. Heavy-quarkonium production naturally involves both perturbative and non-perturbative QCD dynamics, from the production of the heavy $Q Q ˉ$ pair to its formation into a physical bound state. Within NRFF1.0, Non-Relativistic Quantum Chromodynamics (NRQCD) provides the theoretical framework for calculating the FF inputs at the initial scale, which are subsequently evolved through the HF-NRevo scheme. This setup provides a precision baseline for investigating the underlying partonic hierarchy and jet structure across the moderate- to high-transverse-momentum regime. The explicit treatment of partonic channels and heavy-flavor thresholds makes this framework particularly suitable for exploring quarkonium-in-jet fragmentation, jet-quenching sensitivity, energy-loss mechanisms, and the emergence of medium-modified fragmentation patterns in the quark-gluon plasma.
↳ hep-phhep-exhep-thnucl-ex+1