Nuclear Theory·nucl-th

Wednesday·July 2, 2025

15 papers—5 primary·10 cross-listed

01
Shell effects in quasi-fission for calcium induced reactions forming thorium isotopes
C. Simenel · A.S. Umar · K. Godbey · P. McGlynn
Quantum shell effects induce an asymmetric fission mode in actinides, which disappears in neutron deficient isotopes. Quasi-fission, characterized by a significant mass transfer in heavy ion collisions at low-energies, is expected to be affected by similar shell effects. This is studied in 40-56Ca+176Yb reactions with the time-dependent Hartree-Fock approach. All reactions exhibit a mass equilibration process that stops when a heavy fragment with Z~54 protons is formed. Unlike the fission of thorium compound nuclei, quasi-fission does not exhibit a transition to symmetric modes in neutron deficient systems. This observation is interpreted in terms of potential energy surfaces that show a persistence of an asymmetric valley with an increasing barrier preventing its population in fission of the most neutron deficient thorium isotopes.
nucl-thPLB(2025)·4 citations
02
Optimized binning for response function reconstruction via Chebyshev expansions
Immo C. Reis · Joanna E. Sobczyk · Sonia Bacca
We propose an optimized histogram binning strategy to reconstruct nuclear response functions via the Chebyshev expansion bound-state method. Our approach employs a stochastic regularization of the density of states to define adaptive, equal-area bins. Using the deuteron solved in a harmonic-oscillator basis with a chiral interaction, we benchmark on dipole and longitudinal responses, obtaining excellent agreement with exact theory and experiment. This general framework readily extends to other many-body systems and opens the door to new ab initio calculations of lepton-nucleus cross sections in medium-mass nuclei.
nucl-thPRC(2025)·1 citation
03
Microscopic pairing in fission dynamics
A. Zdeb · A. Baran · S.A. Giuliani · L.M. Robledo · M. Warda
Nuclear fission can be modelled as a quantum tunneling process driven by the interplay between the nuclear binding energy and the collective inertia. Within the Wentzel-Kramers-Brillouin formalism, spontaneous fission half-lives can be obtained by minimizing the action integral in the multidimensional space of collective degrees of freedom. Hence, including the relevant collective variables is crucial for properly describing spontaneous fission probabilities. Pairing correlations play an essential role in this evaluation since the collective inertia decreases as the inverse of the square of the pairing gap, and, therefore, they should be considered as a relevant degree of freedom on the same footing as deformation parameters. In this work, we show that the spontaneous fission half-lives in fermium isotopes can be reproduced in a microscopic theory by considering the least-action fission path in a two-dimensional space with constraints on the quadrupole moment and pairing correlations. We consider two microscopic quantities as degrees of freedom associated with pairing: the pairing gap parameter $Δ$ , and the particle number fluctuations $⟨ Δ N^{2} ⟩$ . Least-action paths, computed using the Dijkstra algorithm, are compared with minimum-energy paths, highlighting the importance of pairing correlations as a dynamical degree of freedom.
nucl-thPRC(2025)·2 citations
04
Collectivity of rotational motion in $^{220}$ Rn and $^{226}$ Ra
Artur Dobrowolski · Katarzyna Mazurek · Krzysztof Pomorski
Calculations to reconstruct rotational level patterns in the $^{220}$ Rn and $^{226}$ Ra nuclei have been performed using a collective quadrupole+octupole approach with microscopic mass tensor and moments of inertia dependent on deformation and pairing degrees of freedom. The main objective is to quantitatively confirm the known experimental observations that the Rn nucleus passes from octupole vibrational to octupole deformed with increasing rotation frequency, while the Ra nucleus is relatively weakly affected by collective rotation, being octupole deformed from the beginning. The collective potential in a nine-dimensional collective space is determined using the macroscopic-microscopic method with Strutinsky and the BCS with an approximate particle number projection microscopic corrections. The corresponding Hamiltonian is diagonalized based on the projected solutions of the harmonic oscillators coupled with Wigner functions. Such an orthogonalized basis is additionally symmetrized with respect to the so-called intrinsic symmetrization group, specifically dedicated to the collective space used, to ensure the uniqueness of the Hamiltonian eigen-solutions in the laboratory frame. The response of the pairing and deformation degrees of freedom to external rotation is discussed in the variational approach, where the total energy is minimized by the deformation and pairing variables. Consequently, the corresponding microscopic moments of inertia increase with collective spin (Coriolis {\it antiparing} effect), resulting in effectively lower rotational energy levels I $^{π}$ with respect to pure classical-rotor pattern I(I+1). The obtained comparison of experimental and theoretical rotational energy level schemes, dipole, quadrupole and octupole transition probabilities of B(E $λ$ ) in $^{220}$ Rn and $^{226}$ Ra is satisfactory.
nucl-thnucl-exPRC(2025)·1 citation
05
New angular momentum coupling method based on Wigner rotation theory
Junchao Guo · Yang Sun
We present a new method for constructing the total angular momentum of many-nucleon states. We find that the restrictions imposed by the fermion antisymmetry on the total state are fully absorbed into the single-j space when the broken rotational symmetry of the product state is restored by angular momentum projection. For different j-shells, any total angular momentum that obeys the selection rule is allowed, just as for non-identical particles. The method based on this reorganization is conceptually different from the traditional J and m schemes and may help to improve the efficiency of angular momentum coupling in nuclear many-body calculations.
nucl-thPRC(2025)·1 citation
06
Recurring region for neutron-star observables
Alexander Clevinger🇺🇸 · Zidu Lin🇺🇸 · Milena Albino🇵🇹 · Peter Hammond🇺🇸 · Veronica Dexheimer🇺🇸 · Andrew Steiner🇺🇸
In this letter, we report a novel, somewhat analytical way to produce equations of state (EOSs) that generate particular values of neutron star mass, radius, and tidal deformability. This is possible because our description for the EoS of dense matter can produce recurring regions, small areas where several EoSs cross in the mass-radius and mass-tidal deformability diagrams. We can place recurring regions in desired locations of these diagrams, corresponding e.g., to a given observation. Our prescription is versatile, in the sense that different microscopic models can be used for the low density hadronic phase and high density quark phase, as long as they are connected by a percolation, a description that mimics quark deconfinement and is motivated by QCD. The several EoSs that pass by a recurring region can present different thresholds for the boundaries of the percolation region (different beginning and ending for the quark deconfinement region), as well as different orders for the phase transition at the boundaries. When combining all these features, our prescription allows one not only to produce an EoS that matches an observation, but also one that matches specific chosen criteria for the EoS. The EoSs produced by this new method will be specially suitable for the study of dense-matter properties in future gravitational-wave observations, when both the inspiral and post-merger phase signals will become available. Our numerical code that calculates recurring regions using CompOSE microscopic EoSs is open source and publicly available.
↳ astro-ph.HEnucl-thPRD(2026)·4 citations
07
Studying few cluster resonances with quantum neural network driven iterative Harrow-Hassidim-Lloyd algorithm
Hantao Zhang🇨🇳 · Dong Bai🇨🇳 · Zhongzhou Ren🇨🇳
By using the quantum computing the properties of hypernuclei $_{Λ}^{5}$ He, $_{ΛΛ}^{6}$ He and $_{Λ}^{9}$ Be can be investigated within microscopic cluster model. Our approach combines quantum neural network (QNN) with iterative Harrow-Hassidim-Lloyd (IHHL) algorithm (abbreviated as QNN-IHHL) to solve the quantum many-body problem. To efficiently describe resonance phenomena, we employ complex scaling and eigenvector continuation techniques, providing a robust framework for identifying few-cluster resonance parameters within quantum computing. To validate our quantum algorithm, the resonant $4^{+}$ state of $_{Λ}^{9}$ Be is chosen as a core example. With QNN-IHHL algorithm we realize a fully quantum workflow, which provides a novel framework and some ground work for exploring resonance properties in complex nuclear many-body systems.
↳ quant-phnucl-th1 citation
08
QCD antenna radiative spectrum in dense media within the Improved Opacity Expansion
Matvey V. Kuzmin🇷🇺 · João M. Silva🇪🇸
We compute the double differential inclusive spectrum for the emission of a soft gluon from a color-singlet $q q ˉ$ pair traversing a dense QCD medium. Our results extend the existing literature by simultaneously incorporating both single hard and multiple soft gluon exchanges between the jet and the medium -- an essential ingredient for a complete phenomenological description of jet quenching. Using the Improved Opacity Expansion framework, we provide an analytically tractable treatment, reducing the full cross-section to a set of simple expressions. Our analysis demonstrates that rare hard (Molière) scatterings significantly modify the gluon spectrum at large angles, accelerating the loss of color coherence between the initial quarks. We further quantify whether the modifications are driven by an overall weakening of the interference term, or by more detailed modifications to the fragmentation pattern. Our results provide a direct input for phenomenological jet quenching studies, offering new insights into the role of color decoherence in QCD matter.
↳ hep-phnucl-thJHEP(2025)·11 citations
09
Entanglement, Trace Anomaly and Confinement in QCD
Kiminad A. Mamo🇺🇸
We formulate confinement in QCD as an entropic surface phenomenon. Quark and gluon quantum information is localized on a transverse entangling two-sphere of radius $R_{E E}$ ; at this radius the QCD vacuum -- partitioned by a hadron into interior and exterior regions -- reaches its maximal entanglement entropy. Lattice-QCD determinations of the scalar (trace) gravitational form factors fix both $R_{E E}$ and the transverse trace-anomaly density $ρ_{h} (R_{E E})$ , yielding a parameter-free slope $c_{h} = 8 π^{2} R_{E E}^{2} ρ_{h} (R_{E E})$ and a mechanical entropy $S_{E E} (y) = c_{h} y$ that grows linearly with rapidity $y$ . The entropy gradient $\partial_{R} S_{E E}$ changes sign at $R_{E E}$ : it pushes colored degrees of freedom outward for $r < R_{E E}$ and pulls them inward for $r > R_{E E}$ , thereby localizing them on the codimension-2 entangling two-sphere $Σ_{⊥} = S_{R_{E E}}^{2}$ (which, in the infinite-momentum frame, projects onto the transverse plane), the 'information wall'. This provides a high-energy (large- $y$ ) entropic confinement diagnostic that complements -- rather than replaces -- Wilson's area-law criterion, which probes long-distance dynamics near the rest frame ( $y \to 0$ ). Imposing unitarity on an entropic ansatz for the amplitude yields $σ (s) \propto y^{δ}$ . World data favor $δ = 2$ for elastic $pp (p p ˉ)$ scattering and heavy-quark photoproduction, whereas $ϕ$ photoproduction favors a softer $δ = 0.387$ . All extracted cross sections remain well below the Froissart--Martin bound. These results provide a confinement criterion quantified directly from non-perturbative QCD inputs, unifying the trace anomaly, entanglement entropy, and high-energy scattering within a single quantitative framework.
↳ hep-phhep-thnucl-thPRD(2025)·6 citations
10
Susceptibilities of rotating quark matter in Fourier-Bessel basis
Mamiya Kawaguchi🇨🇳 · Kazuya Mameda🇯🇵
We analyze various two-point correlation functions of fermionic bilinears in a rotating finite-size cylinder at finite temperatures, with a focus on susceptibility functions. Due to the noninvariance of radial translation, the susceptibility functions are constructed using the Dirac propagator in the Fourier-Bessel basis instead of the plane-wave basis. As a specific model to demonstrate the susceptibility functions in an interacting theory, we employ the two-flavor Nambu-Jona-Lasinio model. We show that the incompatibility between the mean-field analysis and the Fourier-Bessel basis is evaded under the local density approximation, and derive the resummation formulas of susceptibilities with the help of a Ward-Takahashi identity. The resulting formulation reveals the rotational effects on meson, baryon number, and topological susceptibilities, as well as the moment of inertia. Our results may serve a useful benchmark for future lattice QCD simulations in rotating frames.
↳ hep-phhep-latnucl-thJHEP(2025)·4 citations
11
Gravitational photon echo
Wen-Te Liao · Sven Ahrens
The generation, controls, and storage of the gravitationally induced photon echo using the 8.4 eV Thorium-229 nuclear clock transition on Earth are theoretically investigated. With its exceptionally narrow linewidth of approximately 1 mHz and high quality factor in the order of $1 0^{19}$ , the Thorium-229 clock transition allows for the potential detection of gravitational-redshift effects at millimeter-scale altitude variations. Moreover, the 1740-second half lifetime of the Thorium-229 isomeric state allows for the slow movement of the system within its coherence time. Along this line, we explore the generation, controls, and storage of photon echo arising from a rotation induced inversion of the gravitational frequency shift in a single target or in multiple equally spaced samples. Our approach lays the foundation for the controllable gravitational quantum optics on Earth.
↳ quant-phgr-qcnucl-th0 citations
12
Energy dependence of rescattering effect on vector mesons spin alignment at RHIC
Zihan Liu🇨🇳 · Ziyang Li🇨🇳 · Wangmei Zha🇨🇳 · Zebo Tang🇨🇳
Spin alignment of vector mesons in heavy-ion collisions provides a novel probe of quark polarization and hadronization mechanism in quark-gluon plasma. Hadronic rescattering may affect the measured spin alignment of vector mesons due to non-uniform rescattering probability in non-central heavy-ion collisions. Using the UrQMD model, we systematically investigated the hadronic rescattering effect on the measurement of $ρ_{00}$ , the spin alignment parameter, for $K^{* 0}$ , $ϕ$ , and $ρ^{0}$ mesons in Au+Au collisions at $s_{NN}$ = 7.7 - 200 GeV. Our results reveal that the measurable $ρ_{00} - 1/3$ remains unaffected for $ϕ$ , while shows significantly negative (positive) deviations for $K^{* 0}$ and $ρ^{0}$ with respect to the reaction (production) plane. Quantitatively, the maximum deviation reaches $- 0.0056$ ( $0.0268$ ) for $K^{* 0}$ and $- 0.0122$ ( $0.0414$ ) for $ρ^{0}$ with respect to the reaction (production) plane. Notably, the deviations in $ρ_{00}$ for both $K^{* 0}$ and $ρ^{0}$ increase monotonically with increasing collision energy. These findings underscore the critical necessity of accounting for rescattering effects when interpreting spin alignment measurements of short-lived vector mesons in heavy-ion collisions.
↳ nucl-exhep-exhep-thnucl-thPLB(2026)·3 citations
13
Hybrid Quark Stars with Quark-Quark Phase Transitions
Zongcan Yang🇨🇳 · Tianxiong Zeng🇨🇳 · Yan Yan🇨🇳 · Wen-Li Yuan🇨🇳 · Chen Zhang🇨🇳 · Enping Zhou🇨🇳
We explore the possibility of phase transitions between different quark matter phases occurring within quark stars, giving rise to the hybrid quark stars (HybQSs). First, we obtain the generic phase diagram of possible mass-radius relation forms for the HybQSs. Then, utilizing a well-established general parameterization of interacting quark matter, we construct quark star models featuring sharp first-order quark-quark phase transitions of various types, in contrast to the hadron-quark transition in conventional hybrid stars. We systematically investigate how recent observations, such as the pulsar mass measurement $M_{TOV} ≳ 2 M_{⊙}$ and the GW170817's tidal deformability bound $Λ_{1.4 M_{⊙}} < 800$ , constrain the viable parameter space. We also identified twin stars in some of the HybQS parameter space. Furthermore, we found that the quark-quark phase transitions in hybrid quark stars may also cause the deviation from the approximate universal relation between the dominant postmerger frequency $f_{peak}$ and tidal deformability $Λ_{1.35 M_{⊙}}$ , which was previously believed to only be caused by the hadron-quark phase transitions in hybrid neutron stars. This work unveils new possibilities of phase transitions and the resulting new types of compact stars in realistic astrophysical scenarios.
↳ astro-ph.HEgr-qchep-phnucl-thPRD(2026)·11 citations
14
Burgers equation for the bulk viscous pressure of quark matter
José Luis Hernandez🇪🇸 · Cristina Manuel🇪🇸 · Saga Säppi🇪🇸 · Laura Tolos🇪🇸
The dissipative properties of relativistic strongly interacting nuclear matter significantly influence the damping of stellar oscillations and density fluctuations during compact star mergers. In this work, we derive the evolution equation for the bulk viscous pressure in unpaired quark matter under small deviations from equilibrium. Our analysis reveals that it behaves like a two-component Burgers fluid. We identify four key transport coefficients -- two relaxation times and two bulk viscosity coefficients -- expressed in terms of equilibrium parameters and electroweak nonleptonic and semi-leptonic decay rates. The transport coefficients are evaluated for two distinct equations of state: one based on perturbative quantum chromodynamics and the other on a modified MIT bag model, valid in different density regimes. We also determine the temperature and density region where nonleptonic electroweak processes dominate the dissipation. Our formulation establishes a new way of describing bulk viscous effects in quark matter, applicable for numerical simulations of compact star mergers.
↳ hep-phgr-qcnucl-thPRD(2026)·7 citations
15
Interplay of prompt and non-prompt photons in photon-triggered jet observables
Chathuranga Sirimanna🇺🇸 · Yasuki Tachibana · Abhijit Majumder · Aaron Angerami · Ritu Arora · Steffen Bass · Yi Chen · Ritoban Datta · Lipei Du · Raymond Ehlers · Hannah Elfner · Rainer J. Fries and 40 other authors
Prompt photons are important yet challenging to observe in relativistic heavy-ion collisions, as they are produced in the early stages and traverse almost the entire QGP medium without interaction. Experimental analyses typically employ isolation cuts, in the hope to identify prompt photons. Most theoretical studies consider only events with actual prompt photons, assuming no contribution from isolated non-prompt photons to reduce computational cost. For the first time, we present a study that compares simulation results generated using inclusive (bremsstrahlung) and prompt-photon events with multiple experimental observables for both $p - p$ and $P b - P b$ collisions at $5.02$ TeV. Simulations are carried out using the multi-stage JETSCAPE framework tuned to describe the quenching of jets and hadrons. Isolated non-prompt photons are generated in hard photon bremsstrahlung, where the photon is radiated at a sufficient angle to the jet. Several photon triggered jet and jet substructure observables show significant contributions from inclusive photons, yielding an improvement in comparison with experimental data. Novel photon triggered jet substructure observables are also expected to show new structures, yet to be detected in experiment. This effort examines the significance of isolated non-prompt photons using parameters tuned for a simultaneous description of the leading hadron and jet spectrum, and thus provides an independent verification of the multistage evolution framework.
↳ hep-phnucl-exnucl-thEPJ Web Conf.(2025)·0 citations

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first authorsco-authorsvia INSPIRE