Nuclear Theory·nucl-th

Thursday·May 22, 2025

12 papers—7 primary·5 cross-listed

01
Relaxation Time Approximation for a multi-species relativistic gas
Gabriel S. Rocha · Gabriel S. Denicol
We generalize a recent prescription for the relaxation time approximation for the relativistic Boltzmann equation for systems with multiple particle species at finite temperature. This is performed by adding counter-terms to the traditional Anderson-Witting ansatz for each particle species. Our approach allows for the use of momentum-dependent relaxation times and the obedience of local conservation laws regardless of the definition of the local equilibrium state. As an application, we derive the first order Chapman-Enskog corrections to the equilibrium distribution and display results for the hadron-resonance gas. We also demonstrate that our collision term ansatz obeys the second law of thermodynamics.
nucl-thhep-phPRD(2025)·3 citations
02
An Overview of the MUSES Calculation Engine and How It Can Be Used to Describe Neutron Stars
Mateus Pelicer · Veronica Dexheimer · Joaquin Grefa
For densities beyond nuclear saturation, there is still a large uncertainty in the equations of state (EoS) of dense matter that translate into uncertainties in the internal structure of neutron stars. The MUSES Calculation Engine provides a free and open-source composable workflow management system, which allows users to calculate the EoS of dense and hot matter that can be used, e.g. to describe neutron stars. For this work, we make use of two MUSES EoS modules, Crust Density Functional Theory and Chiral Mean Field model, with beta-equilibrium with leptons enforced in the Lepton module, then connected by the Synthesis module using different functions: hyperbolic tangent, Gaussian, bump, and smoothstep. We then calculate stellar structure using the QLIMR module and discuss how the different interpolating functions affect our results.
nucl-thastro-ph.HEUniverse(2025)·3 citations
03
Deformation of Jets Induced by Ambient Medium Flow
Arjun Sengupta🇺🇸 · Rainer J. Fries🇺🇸
The evolution of jets showers in high energy nuclear collisions is influenced in various ways by the presence of a surrounding medium. The interaction of jet constituents with the medium can happen during the partonic stage of the jet, during hadronization, and even during its hadronic stage. We demonstrate how flow of the ambient medium in a direction transverse to the jet can introduce both dipole and quadrupole defomations. We propose to analyze the $n = 1$ and $n = 2$ harmonic deformations of soft and semi-hard hadrons or subjets in a jet with respect to the jet core using the method of $q$ -vectors. We discuss simulations which show how the transverse shapes and their preferred angles evolve when the ambient environment of jets changes from the vacuum to a parton medium without flow and finally to a medium with various rates of transverse flow. Our study includes the effects of both flow during the development of the parton shower and hadronization. The existence of dipole deformations, and the correlation of the angles of dipole and quadrupole deformations could constitute promising experimental signals for the presence and size of ambient transverse flow.
nucl-thEPJ Web Conf.(2025)·2 citations
04
Low-energy $^{12}$ C continuum states in three- $α$ model
Souichi Ishikawa
The electric multipole strength distributions for transitions from the $^{12} C (0_{1}^{+})$ ground state to $3 α$ ( $0^{+}$ , $1^{-}$ , $2^{+}$ , and $3^{-}$ ) continuum states are studied in terms of $3 α$ model. Several sets of the $3 α$ Hamiltonian are introduced phenomenologically with conventional $α$ - $α$ interaction potentials and $3 α$ potentials with different range parameters. The transition strength distributions are obtained from wave functions of $3 α$ bound- and continuum states calculated by the Faddeev three-body formalism. From these strength distributions, the resonance parameters (energy, $3 α$ -decay width, and transition strength) of $3 α$ resonance states are extracted. Dependencies of these observables on interaction potential models are studied to examine the introduced interaction models. Using the transition strength distributions, excitation-energy spectra in the $^{12} C (α, α^{'}) 3 α$ reaction are calculated to compare with experimental data.
nucl-thnucl-exPRC(2025)·2 citations
05
Robust extrapolation using physics-related activation functions in neural networks for nuclear masses
C. H. Kim · K. Y. Chae · M. S. Smith
Given the importance of nuclear mass predictions, numerous models have been developed to extrapolate the measured data into unknown regions. While neural networks -- the core of modern artificial intelligence -- have been recently suggested as powerful methods, showcasing high predictive power in the measured region, their ability to extrapolate remains questionable. This limitation stems from their `black box' nature and large number of parameters entangled with nonlinear functions designed in the context of computer science. In this study, we demonstrate that replacing such nonlinear functions with physics-related functions significantly improves extrapolation performance and provides enhanced understanding of the model mechanism. Using only the information about neutron (N) and proton (Z) numbers without any existing global mass models or knowledge of magic numbers, we developed a highly accurate model that covers light nuclei (N, Z > 0) up to the drip lines. The extrapolation performance was rigorously evaluated using the outermost nuclei in the measurement landscape, and only the data in the inner region was used for training. We present details of the method and model, along with opportunities for future improvements.
nucl-th0 citations
06
Quadrupole Strength in Isobaric Triplets
B. C. Backes · J. Dobaczewski · D. Muir · W. Nazarewicz · P.-G. Reinhard · M. A. Bentley · R. Wadsworth
The dependence of the $E 2$ matrix elements on isospin projection $T_{z}$ is linked to the conservation of the isospin symmetry. To study this conjecture, we calculated the $B (E 2 : 2^{+} \to 0^{+})$ rates for the even-even $T = 1$ mirror nuclei with $42$ $\leq$ $A$ $\leq$ $98$ within nuclear density functional theory, employing the generalized Bohr Hamiltonian, and carrying out angular momentum projection. We demonstrated that collective effects are crucial for describing experimental data near the $N = Z$ line without invoking explicit beyond-Coulomb isospin symmetry-breaking corrections. We also determined the $B (E 2 ↓)$ values for odd-odd $T_{z} = 0$ nuclei $^{70} B r$ and $^{78} Y$ in doubly-blocked configurations. We discussed the requirements for accurately describing isobaric analog states and emphasized how current theoretical results should be interpreted within the study of isospin symmetry across isospin triplets.
nucl-thPRC(2025)·1 citation
07
Enhancing the creation of elements in laser-assisted heavy-ion fusion reactions
Nicholas Thomson · Laura Moschini · Alexis Diaz-Torres
Low-energy fusion of heavy ions is a fascinating coupling-assisted quantum tunnelling problem, whose understanding is crucial for advancing the synthesis of new elements and isotopes. Quantum dynamical coupled-channels calculations of laser-assisted $^{16}$ O + $^{238}$ U fusion are presented for both a central collision and the total fusion cross-sections, suggesting that laser-nucleus interaction can enhance the average $^{16}$ O + $^{238}$ U fusion probability by $6 - 60%$ at subbarrier energies using quasi-static laser fields of intensity $1 0^{27} - 1 0^{29}$ Wcm $^{- 2}$ and photon's energy of $1$ eV. Femtosecond laser pulses are shown to reduce this enhancement by many orders of magnitude.
nucl-thnucl-exPRC(2025)·1 citation
08
Discovery of the anti-glitch in PSR J1835 $-$ 1106
Mingyang Wang · Peng Liu · Jianping Yuan · Ang Li · Youli Tuo · Shijun Dang · Weihua Wang · Mingyu Ge · Xia Zhou · Na Wang
We report the detection of an anti-glitch with a fractional frequency change of $Δ ν / ν = - 3.46 (6) \times 1 0^{- 9}$ in the rotation-powered pulsar PSR J1835 $-$ 1106 at MJD 55813, based on timing observations collected with the Nanshan 26-m and Parkes 64-m radio telescopes from January 2000 to July 2022. A comparison of the average pulse profiles within $\pm 300$ d of the event reveals no significant morphological changes. We also estimate the angular velocity lag between the normal and superfluid components at the time of the glitch, showing that one of the superfluid glitch models is incompatible with PSR J1835 $-$ 1106 due to its insufficient spin-down rate and angular velocity lag. The wind braking scenario offers a viable alternative, consistent with the observed spin-down behavior, glitch amplitude, and post-glitch recovery. High-cadence, high-sensitivity monitoring of similar events is essential to distinguish between internal (superfluid) and external (wind-related) glitch mechanisms.
↳ astro-ph.HEastro-ph.SRnucl-thApJL·1 citation
09
Model-Independent Determination of the Tidal Deformability of a 1.4 $M_{⊙}$ Neutron Star from Gravitational-Wave Measurements
Chun Huang🇺🇸
Tidal deformability of a 1.4 $M_{⊙}$ neutron star provides a pivotal window into the physics of dense nuclear matter, bridging gravitational-wave(GW), electromagnetic observations and nuclear physics. In this work, we present a novel, data-driven approach to constrain $Λ_{1.4}$ without invoking specific equation-of-state(EOS) models. By interpolating directly over the mass--tidal-deformability posteriors from GW170817, we obtain an EOS-independent constraint of $Λ_{1.4} = 222.8 9_{- 98.85}^{+ 420.33} .$ We further combine these GW-based results with the X-ray EOS-independent constraint from \cite{Huang_2025}, deriving a multimessenger limit of $Λ_{1.4} = 265.1 8_{- 104.38}^{+ 237.88},$ which remains largely EOS agnostic. This framework demonstrates that higher-order terms neglected in linear expansion methods do not significantly affect $Λ_{1.4}$ estimates under current observational uncertainties. As gravitational-wave detectors improve in sensitivity and more binary neutron-star mergers are discovered, our purely data-driven strategy can serve as a robust standard baseline for extracting neutron-star interior properties without relying on unverified EOS models.
↳ astro-ph.HEastro-ph.SRgr-qcnucl-thApJ(2025)·7 citations
10
Reduction in nuclear size and quadrupole deformation of high-spin isomers of 127,129In
A.R. Vernon🇬🇧 · C.L. Binnersley🇬🇧 · R.F. Garcia Ruiz🇺🇸 · K.M. Lynch🇬🇧 · T. Miyagi🇯🇵 · J. Billowes🇬🇧 · M.L. Bissell🇬🇧 · T.E. Cocolios🇧🇪 · J.P. Delaroche🇫🇷 · J. Dobaczewski🇬🇧 · M. Dupuis🇫🇷 · K.T. Flanagan🇬🇧 and 20 other authors
We employed laser spectroscopy of atomic transitions to measure the nuclear charge radii and electromagnetic properties of the high-spin isomeric states in neutron-rich indium isotopes (Z = 49) near the closed proton and neutron shells at Z = 50 and N = 82. Our data reveal a reduction in the nuclear charge radius and intrinsic quadrupole moment when protons and neutrons are fully aligned in 129In(N = 80), to form the high spin isomer. Such a reduction is not observed in 127In(N = 78), where more complex configurations can be formed by the existence of four neutron-holes. These observations are not consistently described by nuclear theory.
↳ nucl-exnucl-thphysics.atom-phPRL(2025)·3 citations
11
$ϕ \to 3 π$ and $ϕ π^{0}$ transition form factor from Khuri-Treiman equations
A. Garcia-Lorenzo🇪🇸 · M. Albaladejo🇪🇸 · S. Gonzlez-Solis🇪🇸 · N. Hammoud🇪🇸 · V. Mathieu🇪🇸 · G. Montana🇺🇸 · A. Pilloni🇮🇹 · D. Winney🇩🇪 · A.P. Szczepaniak🇺🇸
This work studies the $ϕ \to 3 π$ decay and the $ϕ \to π^{0} γ^{*}$ transition form factor, utilizing the Khuri-Treiman formalism to account for analyticity, crossing, and unitarity. Using once-subtracted dispersion relations, we perform a simultaneous fit to the $ϕ \to 3 π$ Dalitz plot distribution and the $ϕ \to π^{0} γ^{*}$ measurements from the KLOE collaboration, finding good agreement with these experimental data. These results reaffirm the applicability of the Khuri-Treiman approach in the analysis of three-body decays. An interesting result is that the subtraction constant appearing in the equations is similar to a sum rule expectation, in contrast to analogous studies of $ω \to 3 π$ decays and $ω \to π^{0} γ^{*}$ , which shows significant deviations. Our results also provide a reasonable description of the trend of the transition form factor data from BaBar in the $e^{+} e^{-} \to ϕ π^{0}$ scattering region. These intriguing theoretical differences between the decays of $ϕ$ and $ω$ could encourage further experimental measurements to assess the discrepancies and refine the theoretical predictions.
↳ hep-phhep-exnucl-thPRD(2026)·6 citations
12
Hidden-Strangeness Tetraquarks in the Dynamical Diquark Model
Shahriyar Jafarzade🇺🇸 · Richard F. Lebed🇺🇸
The dynamical diquark model describes multiquark exotic hadrons in terms of diquark components nucleated by heavy quarks, and successfully explains multiple features of hidden-charm and -bottom exotics. Here we apply the model to the marginally heavy case of hidden-strange states to probe whether mesons near 2 GeV with peculiar properties, such as $ϕ (2170)$ , $f_{2} (2340)$ , and X(2370), are possible tetraquark candidates. We calculate spin-multiplet average masses using potentials obtained through lattice simulations and quark models, and we also describe the detailed spectra of the expected multiplets as a diagnostic to discern the nature of future hadrons likely to be discovered in this mass region by experiments at facilities such as BESIII, JLab, and the EIC.
↳ hep-phnucl-thPRD(2025)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE