Nuclear Theory·nucl-th

Wednesday·January 21, 2026

30 papers—13 primary·17 cross-listed

01
Pauli Consistent $α$ -- $α$ Interaction from Inverse Scattering via Phase Function Wavefunctions and RGM Antisymmetrization
Anil Khachi · Shikha Awasthi · Tarachand Verma · Ranjana Joshi
The present study employs the phase function method (PFM) to construct scattering wavefunctions for the $α$ -- $α$ system, which is central to understanding the structure of $^{8} Be$ . The primary objective is to analyze scattering dynamics through the reconstruction of radial wavefunctions for the $ℓ = 0$ , 2, and 4 partial waves within the PFM framework, thereby avoiding direct numerical integration of the Schrödinger equation. Previously optimized single-term and two-term Morse potentials are used for benchmarking, while a double Gaussian (DG) potential is independently determined using a genetic algorithm. The resulting non-antisymmetrized wavefunctions are subsequently employed as input to the resonating group method (RGM), enabling the incorporation of Pauli exclusion effects. The antisymmetrized wavefunctions obtained in this manner show good agreement with earlier results reported by Hiura \textit{et al.} The quasi-bound state energy for the $ℓ = 0$ partial wave is evaluated using the matrix method and is found to be consistent with the experimental value of $0.08, (0.09)$ ~MeV. The analysis further indicates the presence of two Pauli-forbidden S-wave states, consistent with Levinson's theorem, while the positive-energy solution near $0.08 MeV$ corresponds to the physical $^{8} Be$ resonance. Scattering parameters extracted from the proposed interactions are in good agreement with NLO, NNLO, and empirical results. Overall, the results establish the effectiveness of the PFM-based framework for reconstructing scattering observables and provide further support for the robustness of phenomenological $α$ -- $α$ interaction models.
nucl-th0 citations
02
Nucleon Resonances in Nuclear Matter and Finite Nuclei
Horst Lenske🇩🇪
The theory of nuclear excitations involving nucleon resonances is revisited and significantly extended to asymmetric nuclear matter and higher P- and S-wave $N^{*}$ resonances. Excited states of are described as superpositions of particle-hole configurations including $N N^{^{'} - 1}$ and $N^{*} N^{- 1}$ configurations. Configuration mixing is taken into account on the one-loop level by solving the generalized $N^{*} R P A$ Dyson equation. The underlying coupled channels formalism is derived and response functions is discussed. Applications of the approach are illustrated for charge-exchange modes of asymmetric nuclear matter and finite nuclei. The spectral gross structures of corresponding excitations in finite nuclei are investigated in local density approximation. Applications of the approach to resonance studies by high-energy heavy ion reactions are recapitulated.
nucl-thhep-phActa Phys.Polon.B(2026)·0 citations
03
Radiative strength functions from the energy-localized Brink-Axel hypothesis
Oliver C. Gorton · Konstantinos Kravvaris · Jutta E. Escher · Calvin W. Johnson
Radiative strength functions (RSFs) model the bulk electromagnetic response of highly-excited nuclei and are critical inputs for statistical reaction codes. In this paper, we present a definition of the RSF that is consistent with Hauser-Feshbach reaction codes and that can be efficiently computed with the shell model using the Lanczos strength-function (LSF) method. We introduce a variant of the shell model LSF method that exploits the energy-localized Brink-Axel hypothesis, which makes it possible to compute both electric and magnetic RSFs across all energies relevant to capture reactions. We verify agreement with the conventional definition of RSFs with benchmark calculations of $^{24}$ Mg, then present novel results for $^{56}$ Fe. For $^{56}$ Fe we find that: (i) the M1 RSF shape evolves smoothly with excitation energy, consistent with the energy-localized Brinkl-Axel hypothesis, (ii) both M1 and E1 transitions contribute significantly to the radiative strength below the photo-absorption threshold, and (iii) within the sdpf model space, the strength below 3 MeV observed in Oslo-type experiments cannot be fully reproduced. These results pave the way for a coherent microscopic description of the RSFs and further motivate the use of energy-dependent RSFs in modern reaction codes.
nucl-thPRC(2026)·2 citations
04
Signatures of QCD conductivities in heavy-ion collisions
Akihiko Monnai🇯🇵 · Grégoire Pihan🇺🇸 · Björn Schenke🇺🇸 · Chun Shen🇺🇸
Dissipative processes are pivotal for understanding the hydrodynamic evolution of hot and dense QCD matter created in relativistic nuclear collisions. The interplay of multiple conserved charges -- net baryon, strangeness, and electric charge -- is of particular interest. We simulate the longitudinal hydrodynamic evolution with the three diffusion currents in a hydrodynamic model with a lattice-QCD-based equation of state, NEOS-4D, and estimate rapidity distributions including diffusive corrections to the phase-space distribution in the presence of multiple charges, which ensure charge conservation at particlization. We determine the response of particle yields at midrapidity to changes in the diagonal and off-diagonal conductivities. Inversely, we find that most components of the conductivity matrix can be constrained experimentally using identified particle multiplicities at different collision energies.
nucl-thhep-phnucl-exPRC(2026)·2 citations
05
Revisiting $^{7}$ Be Weak and Radiative Transition Rates in Big Bang Nucleosynthesis: Implications for the Primordial Lithium Problem
Simone Taioli🇮🇹 · Francesca Triggiani🇮🇹 · Stefano Simonucci🇮🇹
The primordial 7Li abundance predicted by standard Big Bang nucleosynthesis (BBN) exceeds observations in old, metal-poor stars by a factor of 3-4. Since most primordial 7Li is produced as 7Be and subsequently converted by electron capture (EC), additional 7Be destruction channels may affect its final abundance. We investigate EC and antineutrino capture (AC), positron decay from the 7Be nuclear excited state, and proton capture (PC), including 7Be(p,gamma)8B, stimulated emission (SE), plasma screening, and a three-body Auger-like channel transferring the capture energy to a continuum electron. Weak rates are calculated from first principles using perturbation theory with explicitly evaluated hadronic and leptonic currents, while thermally averaged nuclear rates are obtained from the relevant cross sections over 10 < kT < 100 keV. The EC rate rapidly decreases as the Universe expands and cools, while AC enhances weak destruction mainly at early times. SE and screening increase the 7Be(p,gamma)8B rate by only 1-3% at kT about 87 keV. The Auger-like cross section is about 4 x 10^-3 of the radiative channel at kT = 100 keV and falls to about 10^-10 at 10 keV. Our first-principles weak rates differ substantially from previous log(ft)-based estimates, yielding a 7Be half-life of about two days under BBN conditions, nearly one order of magnitude different from phenomenological predictions. Nevertheless, EC, PC, and beta+ decay provide only percent-level corrections to the dominant 7Be(n,p)7Li channel and cannot resolve the cosmological lithium problem. These results motivate a first-principles reassessment of the full BBN nuclear network before invoking physics beyond the Standard Model.
nucl-thastro-ph.COastro-ph.HEastro-ph.SR+10 citations
06
Microscopic investigation of magnetic and antimagnetic rotational motion in atomic nuclei
W. Tawseef · Nazira Nazir · S. Jehangir · J. A. Sheikh · C. Majumder · S. Chakraborty · G. B. Vakil · G. H. Bhat · N. A. Rather
In the present work, we have generalized the projected shell model (PSM) approach to include the quasiparticle excitations from two major oscillator shells, and have also extended the basis space to five-quasiparticle configurations for odd-mass nuclei. The magnetic and antimagnetic rotational structures observed in odd-neutron Pd- and Cd-isotopes have been investigated as a first major application of the new development. It is shown that PSM approach provides a reasonable description of the observed properties of magnetic and antimagnetic rotational bands.
nucl-thPRC(2026)·0 citations
07
Numerical study of the two-boson bound-state problem with and without partial-wave decomposition
Wolfgang Schadow
The validation of numerical methods is a prerequisite for reliable few-body calculations, particularly when moving beyond standard partial-wave decompositions. In this work, we present a precision benchmark for the two-boson bound-state problem, solving it using two complementary formulations: the standard one-dimensional partial-wave Lippmann--Schwinger equation and a two-dimensional formulation based directly on vector variables. While the partial-wave approach is computationally efficient for low-energy bound states, the vector-variable formulation becomes essential for scattering applications at higher energies where the partial-wave expansion converges slowly. We demonstrate the high-precision numerical equivalence of both methods using rank-one separable Yamaguchi potentials and non-separable Malfliet--Tjon interactions. Furthermore, for the Yamaguchi potential, we derive exact analytical expressions quantifying the systematic errors introduced by finite momentum- and coordinate-space cut-offs. These analytical bounds provide a rigorous tool for disentangling discretization errors from truncation effects in few-body codes. The results establish a highly controlled methodological benchmark that provides a detailed baseline for vector-variable algorithms intended for more complex three- and four-body calculations.
nucl-thFew Body Syst.(2026)·1 citation
08
Trace Anomaly of Cold Dense Matter Constrained by Collective Flow
Bao-An Li🇺🇸
The trace anomaly of dense matter, $Δ \equiv 1/3 - P / ε$ , defined through the ratio $w \equiv P / ε$ of pressure $P$ to energy density $ε$ , quantifies deviations from conformal symmetry and provides a dimensionless measure of the stiffness of the equation of state (EOS) relevant for both neutron stars and heavy-ion collisions. While $Δ (ε)$ has recently been inferred from neutron star observations, we report the first Bayesian extraction of the trace anomaly from collective flow observables in intermediate-energy heavy-ion collisions. By employing transport-model simulations that explicitly decouple the cold matter mean-field potential from thermal effects, we directly constrain the EOS of cold dense matter. Remarkably, the trace anomaly inferred from laboratory flow data agrees quantitatively, within $68%$ credible intervals, with independent astrophysical posterior bands. This nontrivial agreement demonstrates that heavy-ion collisions and neutron star observations probe the same macroscopic properties in a mutually consistent way, establishing the dense-matter trace anomaly as a composition-insensitive macroscopic bridge observable across widely different physical environments.
nucl-thastro-ph.HEhep-phnucl-exPRL(2026)·8 citations
09
Superfluid Band Theory for the Rod Phase in the Magnetized Inner Crust Matter: Entrainment, Spin-orbit Coupling, Spin-triplet Pairing
Kenta Yoshimura · Kazuyuki Sekizawa
The inner crust of neutron stars hosts a rich variety of nuclear phenomena and provides a unique environment for exploring microscopic nuclear properties relevant to diverse astrophysical observations. Particularly magnetars, which possess extremely strong magnetic-fields, have attracted increasing attention in connection with nuclear spin dynamics and unconventional pairing correlations. This work is dedicated to develop a comprehensive theoretical framework to describe the structures and properties of two-dimensional (rod-phase) matter in the neutron star inner crust, incorporating band-structure effects, neutron spin-triplet pairing, and strong magnetic-fields on an equal footing. The main results of this study can be summarized as follows. In the first place, the magnetic-fields of the order of $1 0^{16}$ G are found to substantially enhance the neutron effective mass by a factor of approximately $1.5$ , indicating a significant modification of entrainment properties in strongly magnetized crustal matter. In the second place, while the overall behavior of pairing phase transitions is qualitatively similar to that observed in one-dimensional systems studied previously, the present two-dimensional calculations reveal a nontrivial role of the spin-orbit interaction in inducing spin-polarization under magnetic fields. In the third place, concerning spin-triplet superfluidity, the rank-0 component is shown to emerge as a consequence of magnetic-field-induced spin-polarization, irrespective of the presence of spin-triplet pairing interactions, whereas the rank-2 component appears only when the corresponding interaction channel is included.
nucl-th4 citations
10
Pairing correlations, orientations and quantum fluctuations in one- and two-nucleon transfer reactions at sub-barrier energies
Dandan Zhang · Bo Li · Dario Vretenar · Tamara Nikšić · Pengwei Zhao · Jie Meng
This work investigates one- and two-neutron transfer in the $^{96} Zr +^{40} Ca$ reaction at sub-barrier energies using a microscopic framework based on time-dependent covariant density functional theory (TD-CDFT). Pairing correlations are incorporated via the time-dependent BCS approximation, which is shown to significantly enhance pair transfer, as evidenced by an increased two-neutron transfer probability. The oblate deformation of $^{96}$ Zr causes the transfer probabilities to vary by orders of magnitude with orientation; a direct comparison with experiment is enabled by averaging results over thirteen systematically chosen orientations. While the orientation-averaged one-neutron transfer probabilities agree well with data, the two-neutron channel is suppressed below the Coulomb barrier. This suppression is attributed to missing quantum fluctuations in the semiclassical TD-CDFT approach. To test this, we employ the generalized time-dependent generator coordinate method (TDGCM), which confirms that quantum fluctuations are essential for an accurate description of sub-barrier two-neutron transfer dynamics.
nucl-thnucl-exPRC(2026)·1 citation
11
Comparative study of quartet superfluid state: Quartet Bardeen-Cooper-Schrieffer theory and generalized Nambu-Gor'kov formalism
Yixin Guo · Hiroyuki Tajima · Haozhao Liang
We theoretically investigate a quartet superfluid state in fermionic matter by using the quartet Bardeen-Cooper-Schrieffer (BCS) variational theory and the Green's function method. We demonstrate that the quartet BCS theory with the multiple-infinite-product ansatz successfully reproduces an exact four-body result in a one-dimensional four-component Fermi gas at the dilute limit, in contrast to the single-infinite-product ansatz. To see the validity of the quartet BCS state, we derive the self-consistent equation for the quartet superfluid order parameter within the generalized imaginary-time Nambu-Gor'kov formalism, which is found to be consistent with the quartet BCS variational equation. Moreover, by numerically computing the momentum-resolved single-particle spectral function in a one-dimensional system, we discuss how the single-particle spectra evolve with increasing the strength of the four-body cluster formation. We show that a coherent BCS-like quasiparticle branch on the weak-coupling side evolves into a strongly damped, continuum-dominated spectrum in the strong-coupling side, while nonzero quartet superfluid order parameter persists throughout the crossover regime. Our results would be useful for understanding beyond-BCS pairing effects and four-body cluster formations in fermionic systems in an interdisciplinary way.
nucl-thcond-mat.quant-gascond-mat.supr-conphysics.atom-ph1 citation
12
On the Realization of Quantum State Teleportation in Proton Systems
H. Witala🇵🇱
We discuss how to generate entangled Bell states of two nucleons using unpolarized nucleon-nucleon scattering or the exclusive deuteron breakup reaction. We follow the the approach of Z. X. Shen et al., arXiv:2510.24325v1 [nucl-th], where Bell states were identified in unpolarized proton-proton elastic scattering. We confirm these results and show that, in the unpolarized proton-deuteron breakup reaction, it is also possible to generate proton-proton entangled Bell states in kinematically complete proton-proton quasi-free scattering (QFS) and final-state interaction (FSI) configurations. We also discuss an experimental setup that, by exploiting such entangled states, could enable the teleportation of quantum mechanical states in a three-proton system. Such an experiment requires triple coincidences among the outgoing nucleons, which precludes the use of entangled Bell states generated with extremely polarized incoming particles. Since counting rates for unpolarized reactions are much higher than for polarized ones, the present results open a pathway toward searching for signatures of quantum state teleportation in hadronic systems.
nucl-thPRC(2026)·1 citation
13
Influence of Finite-Nuclei Constraints on High-Density Transitions and Neutron Star Properties
Anagh Venneti · Sarmistha Banik · Bijay K Agrawal
We construct posterior distributions of the equation of state (EoS) for matter beyond the inner crust of neutron stars by incorporating finite nuclei (FN) constraints within relativistic mean field models. These constraints are implemented in three complementary ways: (i) through theoretical bounds on the EoS, (ii) implicitly via nuclear matter parameters, and (iii) explicitly by enforcing consistency with experimental binding energies and charge radii of selected nuclei. The resulting low-density nucleonic EoSs are subsequently matched to a model-agnostic speed-of-sound parametrization, constrained by astrophysical observations, including NICER mass-radius measurements, tidal deformability limits from GW170817, and lower bounds on the maximum neutron-star mass inferred from radio pulsar observations. We find that the admissible range of the transition density is strongly sensitive to the choice of the low-density EoS. In particular, the inclusion of explicit FN constraints significantly reduces the allowed parameter space of the nucleonic EoS at low densities, narrowing the transition-density range by nearly a factor of two. Consequently, neutron-star properties inferred from EoSs with explicit FN constraints differ substantially, with especially pronounced effects for low-mass neutron stars and their correlations with nuclear matter parameters. A quantitative comparison, using metrics based on Mahalanobis distance, shows consistency of the explicit constraints with PSRs J0740+6620, J0030+0451, and J0437-4715, but suggest a possible tension with PSR J0614-3329. These findings underscore the critical importance of a consistent treatment of finite-nuclei properties for reliably inferring the behavior of high-density matter and the presence of possible phase transitions from astrophysical observations.
nucl-thastro-ph.HE2 citations

Affiliations

first authorsco-authorsvia INSPIRE