Nuclear Theory·nucl-th

Wednesday·February 18, 2026

10 papers—4 primary·6 cross-listed

01
Perturbative calculations of nucleon-deuteron elastic scattering in chiral effective field theory
Lin Zuo🇨🇳 · Wendi Chen🇨🇳 · Dan-Yang Pang🇨🇳 · Bingwei Long🇨🇳
We develop a framework for calculating nucleon-deuteron scattering using strict perturbation theory for treating subleading interactions in chiral effective field theory (ChEFT). Rather than using direct evaluations in the distorted-wave expansion, our approach solves a hierarchy of integral equations to obtain subleading scattering amplitudes. A benchmark with the wave packet continuum-discretization is performed. This framework benefits from the fact that the renormalization-group invariance chiral forces involves only a limited number of two-body partial waves at leading order. We use it to calculate nucleon-deuteron elastic scattering differential cross sections and analyzing powers up to next-to-leading order.
nucl-thCPC(2026)·1 citation
02
Description of nucleon elastic scattering off $^{6}$ Li with the four-body continuum-discretized coupled-channels method
Kazuyuki Ogata · Shoya Ogawa
Background: Neutron reactions off lithium isotopes up to 50 MeV are important for nuclear data science, around the International Fusion Material Irradiation Facility (IFMIF) facility in particular. Purpose: We aim at constructing a semi-microscopic reaction model that describes neutron elastic scattering off $^{6}$ Li up to 50 MeV taking the breakup channels of $^{6}$ Li into account. Methods: We adopt the continuum-discretized coupled-channels method (CDCC) with an $α + p + n$ three-body model of $^{6}$ Li. We employ the $g$ -matrix effective interaction by Jeukenne, Lejeune, and Mahaux (JLM). The renormalization factors of the real and imaginary parts of the JLM interaction are treated as free parameters. Results: The renormalization parameter of the real part of the JLM interaction is found to be constant ( $= 1.1$ ), whereas that for the imaginary part has a smooth energy dependence. The four-body CDCC calculation with these parameters well describes the angular distributions of both proton and neutron elastic scatterings as well as the neutron total cross section and proton total reaction cross section. The applicable energy range is found to be from 7 MeV to 50 MeV. Conclusions: We have constructed a reliable reaction model for describing nucleon- $^{6}$ Li scattering between 7 MeV and 50 MeV. This model can directly be applied to inelastic scattering and breakup reactions for $^{6}$ Li with the help of the complex scaling method.
nucl-th0 citations
03
Development of an accurate formalism to predict properties of two-neutron halo nuclei: case study of $^{22}$ C
Patrick McGlynn🇺🇸 · Chloë Hebborn🇺🇸
When moving away from stability or in loosely-bound systems, few-body clusterized structures like two-neutron halo nuclei appear. These emerge from the interplay between the many- and few-body degrees of freedom, and/or strong coupling between bound and continuum states. This motivates the development of models that can accurately describe few-body dynamics while enforcing shell effects. This work has two goals: understanding how to accurately enforce the Pauli principle in few-body models, as well as presenting new technical developments that allow for more robust and cheaper three-body calculations. We focus on properties of the two-neutron halo 22C, but expect the conclusions to apply to other few-body systems. We use a three-body, hyperspherical harmonics formalism combined with the R-matrix method. We compare predictions for properties of 22C starting from phenomenological interactions and using two methods to remove Pauli-forbidden states, the projection and supersymmetric methods. We also present the algorithms and derivations used. Additionally, we explore model space truncations that allow for reduced computational time. We show convergence of the calculation of both bound and scattering states for $K_{ma x} \sim 40$ . The two methods to enforce the Pauli-exclusion principle lead to different predictions of 22C properties; the projection method is more accurate. We find one efficient channel truncation that reduces the computational cost of our calculations by 20%. Our study clarifies that the projection method is more accurate than the supersymmetric one to enforce the Pauli-exclusion principle. Technical and algorithmic developments enable accurate and efficient computation of two-neutron halo properties. This development paves the way to robust uncertainty quantification in three-body predictions, and is a useful starting point to tackle more complex systems and observables.
nucl-th0 citations
04
Radial oscillations of pulsating neutron stars: The UCIa equation-of-state case
G. Panotopoulos · A. Övgün · T. Iqbal · Y. Kumaran · B. K. Sharma
Radial oscillations provide a clean dynamical test of the high-density stiffness of neutron-star equations of state. We study spherically symmetric pulsations of nonrotating relativistic stars built from cold, charge-neutral, $β$ -equilibrated pure nucleonic matter described within relativistic mean-field theory. As a baseline we adopt the UCIa parameter set [Astron. Astro-phys. 689, A242 (2024)], and we implement high-density stiffening via the $σ$ -cut scheme by adding a regulator potential $U_{cut} (σ)$ [Phys. Rev. C 92, no.5, 052801 (2015), Phys. Rev. C 106, no.5, 055806 (2022)]. For representative choices $f_{s} = 0$ (no cutoff) and $f_{s} = 0.58$ (stiffened), we solve the Tolman-Oppenheimer-Volkoff and tidal perturbation equations to obtain equilibrium sequences, mass-radius relations, and tidal deformabilities. We then derive and solve the linear general-relativistic radial pulsation equations to compute the eigenfrequencies and eigenfunctions of the fundamental and overtone modes. The $σ$ -cutoff suppresses the growth of the scalar field at supranuclear density, increases the pressure, and shifts the maximum mass, radii, and $Λ_{1.4}$ accordingly, while systematically raising the radial-mode frequencies at fixed mass. Using the sign change of $ω_{0}^{2}$ as a stability criterion, we identify stiffened models that remain radially stable up to the observed $\sim 2 M_{⊙}$ mass scale and are consistent with current multimessenger constraints, demonstrating how radial spectra complement static EoS tests.
nucl-thastro-ph.SRgr-qc1 citation
05
Dispersive analysis of the $ϕ \to γ π^{0} π^{0}$ process
Bai-Long Hoid🇩🇪 · Igor Danilkin🇩🇪 · Marc Vanderhaeghen🇩🇪
We present an analysis of the radiative decay $ϕ \to γ π^{0} π^{0}$ in a dispersive framework, where the two-pion subsystem undergoes strong final-state interactions that cover the $f_{0} (500)$ and $f_{0} (980)$ regions. We employ a coupled-channel Muskhelishvili-Omnès framework that allows for a consistent treatment of two scalar resonances and crossed-channel singularities induced by the Born and vector-meson exchanges. We explicitly verify the equivalence between the modified and standard Muskhelishvili-Omnès representations for vector-meson pole contributions when the isoscalar Omnès matrix is chosen asymptotically bounded, and we adopt the standard representation in decay kinematics. This yields, for the first time, a parameter-free dispersive prediction for the kaon Born rescattering, which provides a dominant contribution. To obtain a good fit to the KLOE and SND data, we employ a once-subtracted coupled-channel dispersion relation with heavier left-hand cut contributions and two unknown subtraction constants. The results demonstrate the consistency among the data for $π π$ scattering, $γ γ$ fusion, and $ϕ$ radiative decay, thereby validating the underlying dispersive formalism and the input used for the hadronic Omnès matrix and left-hand cuts.
↳ hep-phhep-exnucl-thPRD(2026)·1 citation
06
Orbital eccentricity can make neutron star g-mode resonances observable with current gravitational-wave detectors
János Takátsy🇩🇪 · Lorenz Zwick🇩🇰 · Pankaj Saini🇩🇰 · Johan Samsing🇩🇰
Dynamical tides can provide us vital information about the properties of neutron star (NS) matter. This is particularly true for g-modes, whose frequency and tidal coupling are highly sensitive to the composition of NSs, especially in their centers, where microphysical models are the least reliable. However, due to their weak coupling to external tidal fields, their effect on the gravitational-wave (GW) signal of binary inspirals can be difficult to observe. Here we show that the detectability of these tides can be significantly enhanced by binary NSs with moderate eccentricities. This is primarily due to higher eccentric harmonics in the early phase of the binary evolution experiencing larger phase shifts, which they transport to the sensitive band of GW detectors. In addition, g-mode tides in eccentric binaries undergo several epicyclic resonances, which also amplify the total phase shift. We demonstrate that these effects increase the detectability of g-mode dynamical tides by more than an order of magnitude for eccentricities of $e_{10Hz} \sim 0.2 - 0.4$ , making it possible to put robust constraints on g-mode properties using current GW detectors, while all relevant models could potentially be constrained with eccentric binary NSs with Einstein Telescope.
↳ astro-ph.HEhep-phnucl-thPRD(2026)·3 citations
07
Back-to-back dijet production in DIS at arbitrary Bjorken-x: TMD gluon distributions to twist-3 accuracy
Swagato Mukherjee🇺🇸 · Vladimir V. Skokov🇺🇸 · Andrey Tarasov🇺🇸 · Shaswat Tiwari🇺🇸 · Fei Yao🇺🇸
We derive the gluon transverse-momentum-dependent (TMD) operator structure of back-to-back quark-antiquark dijet production in deep inelastic scattering at arbitrary Bjorken-x to twist-3 accuracy. Working at leading order in the strong coupling and in the kinematic regime where the transverse momentum imbalance of the jets is much smaller than their individual transverse momenta, we perform a systematic gradient expansion of the quark propagator in a background gluon field. This expansion organizes multiple interactions with the target in terms of longitudinal Wilson lines and gauge-invariant field-strength insertions, yielding a TMD description valid beyond the strict high-energy eikonal (x -> 0) approximation. We obtain explicit cross sections for longitudinally and transversely polarized virtual photons, identifying all contributing gluon TMD operators up to twist-3, including structures involving F_+-, F_ij, and three-gluon correlators. The full longitudinal phase associated with Bjorken-x is retained throughout. In the small-x limit, our results reproduce the known sub-eikonal expressions obtained in the Color Glass Condensate framework, establishing a direct connection between the general-x TMD expansion and high-energy factorization. We further reduce the operator basis using equations of motion, minimizing the number of independent nonperturbative matrix elements entering the cross section. This work provides a systematic foundation for extending TMD analyses of dijet production beyond leading twist, establishing a unified operator framework valid at arbitrary Bjorken x that smoothly interpolates between moderate- and small-x descriptions of gluon TMDs.
↳ hep-phhep-thnucl-thPRD(2026)·9 citations
08
pion-rho Mixing as a mechanism for non-monotonic charged pion behavior in magnetic fields
Ziyue Wang🇨🇳
We investigate whether magnetic field induced $π - ρ$ mixing can explain the non-monotonic behavior of the charged pion reported in lattice QCD. Using a near-pole effective action derived from the SU(2) $_{f}$ Nambu--Jona-Lasinio model, we show that the lowest Landau level charged pion mixes with the longitudinally polarized charged rho meson, which shares the same quantum numbers in a magnetic background. The resulting level repulsion is strongly amplified by the suppression of the rho wave-function renormalization near the pole. As a consequence, the lowest mixed mode develops a turnover as the magnetic field increases, reproducing the qualitative trend seen on the lattice. Comparison with the direct determinant solution of the Landau-projected kernel shows that the mechanism is robust, although the quantitative location of the maximum remains scheme dependent. These results support $π - ρ$ mixing as an important candidate mechanism for charged meson spectra in strong magnetic fields.
↳ hep-phnucl-th7 citations
09
Charm and strange meson fragmentation functions
Roberto C. da Silveira🇧🇷 · Ian C. Cloët🇺🇸 · Bruno El-Bennich🇧🇷 · Fernando E. Serna🇨🇱
Quark fragmentation functions describe the hadronization process of a quark where any of the final-state hadrons carries a fraction of its initial momentum. We compute these fragmentation functions for a cascade that includes pions, kaons, and the charmed $D$ and $D_{s}$ mesons, starting from the elementary quark-to-meson fragmentation process. The latter is obtained from the relevant cut diagram, and employs Poincaré covariant Bethe-Salpeter wave functions and quark propagators. We derive a set of twenty-five coupled jet equations that describe the cascade of emitted mesons in the fragmentation process. Their solutions yield full fragmentation functions that offer a consistent picture of the quark fragmentations across the light and heavy sectors.
↳ hep-phhep-exnucl-th0 citations
10
More uses for Thermal Models
Natasha Sharma🇮🇳 · Lokesh Kumar🇮🇳 · Sourendu Gupta🇮🇳
We explore combinations of particle and anti-particle yields which can be used to test thermal models in a parameter free way. We also explore combinations which can be used to extract $μ_{B} / T$ , $μ_{S} / T$ and $μ_{Q} / T$ . We use experimentally measured particle-antiparticle specific ratios for proton $p$ , Lambda $Λ$ , and cascade $Ξ$ , for $s_{N N} =$ 7.7-39 GeV from RHIC BES phase-1 to extract the $μ_{B, S, Q} / T$ . These compared well with published STAR freeze-out parameters. These combinations are verified to predict a similar combination of $Ω$ yields. We also extend this idea to predict (anti-)nuclei yields at energies where they are not measured. We also update parametrizations for the $s_{N N}$ dependence of freeze-out parameters $T$ and $μ_{B}$ , and present for the first time a similar parametrization of $μ_{S}$ .
↳ hep-phnucl-exnucl-thEPJC(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE