Nuclear Theory·nucl-th

Tuesday·May 5, 2026

16 papers—8 primary·8 cross-listed

01
Multireference Covariant Density Functional Theory with Stochastic Basis
Xin. Zhang · Kouichi. Hagino
Multireference density functional theory (MR-DFT) provides a pivotal microscopic framework for the description of the ground state properties, low-lying nuclear spectra and transition properties of atomic nuclei. Conventionally, practical implementations of MR-DFT rely on empirically chosen generator coordinates, which may omit relevant collective degrees of freedom and thus fail to capture sufficient collective correlations. Here we introduce the stochastic-basis multireference density functional theory (MR-SDFT). This is an extended scheme that augments the MR-DFT toolkit by (i) generating a diverse ensemble of mean-field reference configurations via a stochastic external field and (ii) selecting a compact subspace with Projection-Selection method. The chosen reference configurations are then linearly superposed within the MR-DFT framework to yield spectroscopic observables. Applying this framework to \nuclide[20]{Ne}, \nuclide[24]{Mg} and \nuclide[28]{Si} with the covariant density functional theory (CDFT), it is demonstrated that the MR-SCDFT leads to lower ground-state energies, smaller point-proton rms radius, and a softer ground-state band compared to the conventional MR-CDFT.
nucl-thPLB(2026)·0 citations
02
The atomic nucleus as a bound system of $3 A$ quarks
B.Kosyakov🇷🇺 · E. Popov🇷🇺 · M. Vronsky🇷🇺
The atomic nucleus, viewed as a system of bound quarks, should, in principle, be described within an effective theory of low-energy quantum chromodynamics. This paper provides an overview of recently developed models that embody essential features of the desired effective theory. The Fermi gas model helps explain why the number of $d$ quarks is approximately equal to that of $u$ quarks in stable light nuclei up to $_{20}^{40} Ca$ . A modified bag model accounts for the deviation from this rule in heavier nuclei. With this model, the static properties of a wide range of stable nuclei can be described with reasonable accuracy. To make the most of the modified bag model, it is useful to invoke gauge/gravity duality. A refined version of duality states: ``The dynamics inside an extremal black hole in $AdS_{5}$ is mapped onto the corresponding dynamics of a stable subnuclear system in $R_{1, 3}$ ''. This version of duality allows one to predict the primary decay channel of the lightest glueball. Another implication is that this framework explains why the periodic table contains a finite number of stable elements. Duality makes it possible to calculate the maximum allowed charge $Z_{max}$ of stable heavy nuclei: $Z_{max} \approx 82$ , which is the charge of the $_{82}^{208} Pb$ nucleus.
nucl-thhep-thCPC(2026)·0 citations
03
Relativistic BDNK MHD Evolution in a Boost-Invariant Medium and Its Impact on Dilepton Production
Ankit Kumar Panda🇨🇳 · Rajesh Biswas🇵🇱
In this work, we explore a Bemfica--Disconzi--Noronha--Kovtun (BDNK)-type formulation of relativistic magnetohydrodynamics, providing a causal and stable first-order description of dissipative fluids. We derive coupled evolution equations for the temperature and magnetic field in a boost-invariant Bjorken background, restricting to $(0 + 1)$ D dynamics while retaining all relevant first-order gradients. By varying the transport coefficients, we disentangle the interplay and mutual backreaction between the thermal and electromagnetic sectors. We find that, for comparable transport coefficients, the magnetic field responds more strongly to changes in the temperature evolution, while its feedback on the temperature remains subleading. We further analyze the number density evolution, which is sensitive to both temperature gradients and magnetic-field dynamics. We also investigate implications for dilepton production, where the magnetic field modifies the emission rate via the relaxation time in a kinetic-theory framework. The coupled evolution leads to a suppression of the low-mass dilepton spectrum, primarily driven by enhanced cooling in the presence of positive coupling between temperature gradients and magnetic-field evolution, as compared to scenarios without such feedback.
nucl-thhep-phPRD(2026)·0 citations
04
Relativistic Feshbach-Villars Equation for Two Spin- $0$ Particles
Z. Papp
The Feshbach-Villars version of the relativistic quantum mechanics can be extended for two-body systems in such a way that the center-of-mass motion is separated off. The procedure results in an equation of Feshbach-Villars-type in terms of the relative coordinate.
nucl-thFew Body Syst.(2026)·0 citations
05
Constructing Inverse Potentials from Scattering Phase Shifts using Physics-Informed Neural Networks: Application to Neutron-Alpha Scattering
Ayushi Awasthi Ishwar Kant Arushi Sharma M.R.Ganesh Kumar · O.S.K.S.Sastri
We develop a physics-informed neural networks (PINNs) framework for the inverse scattering problem in nuclear physics and apply it to the $P_{3/2}$ partial wave of neutron-alpha elastic scattering. The radial potential is represented by a feed-forward network whose output is multiplied by a Gaussian envelope, embedding the finite-range condition directly into the architecture rather than through a soft penalty term. This distinction proves essential: without the envelope, the optimizer produces potentials with non-vanishing tails and the resulting phase shifts remain inconsistent with the data regardless of training duration, demonstrating that hard structural constraints are indispensable for physically meaningful solutions to nuclear inverse problems. Phase shifts are generated at each scattering energy by numerically integrating the variable-phase equation with a fourth-order Runge-Kutta scheme, making the entire pipeline end-to-end differentiable.Training converges stably to a loss near $3 \times 1 0^{- 4}$ and recovers a smooth, purely attractive central potential with a well depth of $- 60.47$ ~MeV. Adding the centrifugal barrier to the learned potential reveals a well-defined barrier-well structure that naturally accounts for the $P_{3/2}$ resonance. The extracted resonance parameters, $E_{r} = 0.95$ ~MeV and $Γ_{r} = 0.78$ ~MeV, together with the P-wave effective-range parameters, are in good agreement with expected values. A leave-one-out analysis confirms that the reconstruction is stable against the removal of any single data point. These results establish physics-guided machine learning as a reliable route to potential reconstruction from nuclear scattering data.
nucl-th0 citations
06
Gluon production in the Color Glass Condensate from BCFW recursion
Francois Gelis🇫🇷
In the Color Glass Condensate framework, the colliding projectiles are described as classical color currents. Gluon production at leading order in the coupling is obtained from the retarded solution of the classical Yang-Mills equations, with these currents acting as sources. However, while the final gluon spectrum is gauge invariant, the classical color field $A^{μ}$ from which it is obtained is gauge dependent. This makes the intermediate steps of this approach unnecessarily complicated, as some effort is spent to also determine the gauge dependent part of $A^{μ}$ , which is then discarded when one calculates a gauge invariant observable. In this work, we use a generalization of BCFW recursion applicable to off-shell gluons in order to calculate directly the gauge independent gluon production amplitude. This approach allows all manipulations to be performed in terms of gauge invariant amplitudes instead of gauge dependent Feynman diagrams, and therefore provides a gauge agnostic way to obtain the result.
nucl-thhep-phJHEP(2026)·0 citations
07
New Procedure for the Evaluation of Fission Product Yields: Application to the Spontaneous Fission of $^{252}$ Cf
A. E. Lovell · T. Kawano · P. Talou
Over the last decade, there has been significant improvement in the understanding and modeling of the decay of fission fragments by both prompt and delayed emission. These model improvements open the door for performing consistent evaluations across multiple fission observables, providing not only mean values but also covariances between observables. One such model is the Hauser-Feshbach Fission Fragment Decay model implemented in $BeoH$ , which uses distributions of initial conditions of fission fragments to perform a Hauser-Feshbach decay for prompt neutron and $γ$ -ray emission and evaluated decay data to calculate cumulative fission product yields. This manuscript describes a new evaluation procedure for independent and cumulative fission product yields, including full correlations among the fission products. We use a Bayesian Kalman filter to fit both experimental cumulative fission product yields and those from the ENDF/B-VIII.0 evaluated library, producing mean values and covariances. In addition to comparing the fission products from these optimizations, we calculate prompt and delayed neutron and $γ$ -ray multiplicities using the fitted parameters and compare to some available experimental data. We see reasonable agreement, even when these quantities are not included in the optimization.
nucl-thnucl-ex0 citations
08
Structure of the $^{8}$ B and $^{8}$ Li nuclei and the astrophysical $S_{17} (0)$ -factor of the $^{7}$ Be( $p, γ$ ) $^{8}$ B direct capture process within a three-body model
E.M. Tursunov · D.S. Toshova · S.A. Turakulov
The structure of the ground $(2^{+})$ and excited $(1^{+})$ bound states of the $^{8}$ B and $^{8}$ Li nuclei is studied within the framework of the $α +^{3}$ He( $^{3}$ H)+ $p (n)$ three-body potential cluster model based on the hyperspherical Lagrange-mesh method. The two-body realistic potentials have been applied from the literature. Convergent theoretical estimates for the three-body binding energy and matter radius have been obtained with the maximal hypermomentum $K_{ma x} = 22$ and 28 for the ground and excited $1^{+}$ states, respectively. The ANC value of the virtual transition of the $^{8}$ B nucleus is estimated self-consistently by matching the overlap integral of the $^{8}$ B three-body and the $^{7}$ Be two-body wave functions with it's asymptotics. The obtained values are $0.211$ ~fm $^{- 1/2}$ and $0.739$ ~fm $^{- 1/2}$ in the spin 1 and spin 2 channels, respectively. For the ANC values of the $^{8}$ Li nucleus the estimates $0.220$ ~fm $^{- 1/2}$ and $0.774$ ~fm $^{- 1/2}$ are extracted. The ratio $C^{2} (^{8} B) / C^{2} (^{8} Li) = 0.912$ implies a breaking of the mirror symmetry of the strong nuclear forces of order 27\% due to the Coulomb interaction and the dynamical three-body effects. For the $S_{17} (0)$ -factor an estimate $22.492 \pm 0.014$ eV b was obtained based on the asymptotic theory developed by D. Baye [Phys. Rev. C {\bf 62},065803 (2000)]. The spin 2 channel contributes with $S_{17}^{(2)} (0) = 20.838 \pm 0.014$ eV b, while the spin 1 channel yields $S_{17}^{(1)} (0) = 1.654 \pm 0.003$ eV b. These results for $S_{17} (0)$ are in a good agreement with the estimate $20.8 \pm 0.7 (th) \pm 1.4 (exp)$ eV b of the SF II, but larger than the recommended value $20.5 \pm 0.70$ eV b of the SF III. At the same time, our estimate is very close to the value 22.4 eV b used in the most successful Solar Model BAR2M [W.~Yang and Z.~Tian, AJ {\bf 970} (2024), 38].
nucl-thastro-ph.SRnucl-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE