Nuclear Theory·nucl-th

Wednesday·December 10, 2025

10 papers—4 primary·6 cross-listed

01
Rapidly Spinning Massive Pulsars as an Indicator of Quark Deconfinement
Christoph Gärtlein🇵🇹 · Violetta Sagun🇬🇧 · Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱 · Ilídio Lopes🇵🇹
We study rotating hybrid stars, with particular emphasis on the effect of spin on the deconfinement phase transition and star properties. Our analysis is based on a hybrid equation of state with a phase transition from hadronic matter containing hyperons to color-superconducting quark matter, where the quark phase is modeled within a relativistic density functional approach. By varying the strength of the vector repulsion and diquark pairing couplings in the microscopic quark Lagrangian, we construct a set of hybrid star sequences with different quark-matter onset densities. This framework ensures consistency with astrophysical and gravitational wave constraints on mass, radius, and tidal deformability.
nucl-thastro-ph.HEhep-phJ.Subatomic Part.Cosmol.(2026)·3 citations
02
Wavefunction-Based Emulation of Coupled-Channels Scattering with Non-Affinely Parametrized Interactions
M. Catacora-Rios · Kyle Beyer · Pablo Giuliani · Kyle Godbey · Richard J. Furnstahl · Filomena Nunes
Physics based emulators offer a fast and reliable replacement for an exact solution of the scattering problem in nuclear physics. Previous work developed a reduced-basis emulator for single-channel elastic scattering using an optical potential. Since many reactions of interest can be cast as a coupled-channel problem, the purpose of this work is to extend the RBM to a coupled-channel framework (CC-RBM). Although the framework derived is general, in this work we apply it to reactions where the Hamiltonian coupling term comes from assuming a rotational structure model for the target. From a set of training coupled-channel wavefunctions, we perform a singular value decomposition to obtain a reduced set of basis wavefunctions, and then solve the extended (Petrov-)Galerkin equations. In addition, the empirical interpolation method is used to expand the potentials. We apply the CC-RBM method to elastic and inelastic scattering of neutrons on 48Ca including a quadrupole coupling to populate the first 2+ state, and neutrons on 208Pb, including an octupole coupling to populate its first 3- state. We demonstrate that the CC-RBM calculated cross sections match those obtained using traditional finite-difference methods. We show that the CC-RBM results can reliably reproduce the nuclear scattering cross sections at different energy regimes. The computational accuracy versus time plots demonstrate that the CC-RBM method efficiently increases precision with increasing basis size. Most importantly, for the precisions required in reaction calculations (a percent on the cross section), we find the CC-RBM method offers roughly one and a half orders of magnitude gain in computational speed compared to the traditional coupled-channels solver. However, we also discuss how this scaling becomes less favorable, the larger the number of channels included in the coupled-channel set.
nucl-thPRC(2026)·9 citations
03
The QCD phase diagram
Szabolcs Borsanyi · Paolo Parotto🇮🇹
Strongly interacting matter exhibits new phases under extreme conditions. Matter was exposed to such extremes not only in the Early Universe, but also today in the cores of neutron stars, as well as in laboratory experiments at a much smaller scale. We study the underlying theory, Quantum Chromodynamics (QCD) with the methods of statistical physics and explore the various phases we may encounter in experiment, such as the Quark Gluon Plasma. We briefly summarize the experimental evidence for the new forms of matter and review the theoretical efforts to embed these findings in the broader context of quantum field theory, with special attention to exact and broken symmetries and critical behaviour.
nucl-thhep-lat15 citations
04
A Bayesian Approach Study of Hybrid Neutron Stars
Fábio Köpp🇺🇸 · César H. Lenzi🇺🇸 · César V. Flores🇺🇸 · Débora P. Menezes🇺🇸
In this work, we explore how astronomical observations (specifically measurements of masses, radii, and tidal deformabilities) can constrain the presence of quark matter inside neutron stars, namely the phase transition from nuclear matter to deconfined quark matter. Our approach employs Bayesian analysis to study this phenomenon. Hadronic matter is modeled using the relativistic mean-field (RMF) approximation, for which we have selected two parameter sets: $NL3^{*}\omega\rho$, representing hadronic matter with nucleons only, and $E L 3 ω ρ$ with nucleons only and $E L 3 ω ρ Y$ , which includes hyperons. On the other hand deconfined quark matter is modeled using the vector-MIT bag model. For our purpose, the phase transition is implemented using the Maxwell construction. Bayesian inference is performed by tuning three parameters: the bag constant (i.e. $B^{1/4}$ ), the vector coupling constant $\left(G_{v}\right)$, and the Dirac sea contribution ( $b_{4}$ ). We found that a phase transition could exist at densities below $2.0\,n_{0}$ for both the $E L 3 ω ρ - E L 3 ω ρ Y$ and $N L 3^{*} ω ρ$ parametrizations. As a consequence, our results also indicate that a hybrid neutron star could have a large quark core that comprises more than $80\%$ of its size.
nucl-thastro-ph.HEPRD(2026)·0 citations
05
Theory of inverse beta decay for reactor antineutrinos
Oleksandr Tomalak🇨🇳 · Qishan Liu🇨🇳 · Yu-Feng Li🇨🇳
Inverse beta decay (IBD), $ν_{e} p \to e^{+} n (γ)$ , is the main detection channel for reactor antineutrinos in water- and hydrocarbon-based detectors. As reactor antineutrino experiments now target sub-percent-level sensitivity to oscillation parameters, a precise theoretical description of IBD, including recoil, weak magnetism, nucleon structure, and radiative corrections, becomes essential. In this work, we give a detailed and precise calculation of the total and differential cross sections for radiative IBD, $ν_{e} p \to e^{+} nγ$ . We use a heavy baryon chiral perturbation theory framework, systematically incorporating electroweak, electromagnetic, and strong-interaction corrections. We derive new analytic cross-section expressions, clarify the collinear structure of radiative corrections, and provide a systematic uncertainty analysis. We also discuss phenomenological applications for reactor antineutrino experiments, e.g., JUNO, and neutron decay. Our results enable sub-permille theoretical precision, supporting current and future experiments.
↳ hep-phhep-exnucl-exnucl-thPhys. Rev. D (2026)·8 citations
06
Radiative corrections to inverse beta decay: a precision analysis for reactor neutrinos
Oleksandr Tomalak🇨🇳
We present a complete calculation of radiative corrections to the inverse beta decay reaction, $ν_{e} + p \to e^{+} + n$ , at reactor antineutrino energies using heavy-baryon chiral perturbation theory. Our analysis consistently incorporates quantum electrodynamics, chromodynamics, and electroweak contributions for the first time within this framework. We provide updated, high-precision cross-section predictions with a full error budget and present the positron energy spectrum, including radiative effects. The results are essential for normalizing the reactor antineutrino flux, determining neutrino oscillation parameters with subpercent accuracy, and searching for new physics at nuclear power plants.
↳ hep-phhep-exnucl-exnucl-thPhys. Rev. Lett. (2026)·5 citations
07
(3+1)D event-by-event pre-equilibrium dynamics in heavy-ion collisions
Xiaojian Du🇨🇳 · Sören Schlichting🇩🇪 · Jie Zhu🇨🇳
So far a major source of uncertainty in the study of heavy-ion collisions arises from the early time dynamics which includes initial state and pre-equilibrium dynamics. The state-of-the-art framework, KoMPoST, employs non-equilibrium Green's functions to propagate the initial energy-momentum tensor to the hydrodynamic phase, yet currently only treats transverse plane dynamics under boost-invariant conditions. In this work, we extend KoMPoST to include non-boost-invariant responses to initial conditions, essential for accurately capturing the longitudinal structures observed in heavy-ion collisions. Non-boost-invariant fluctuations on top of a homogeneous background are evolved using (3+1)D response functions calculated in kinetic theory. To assess kinetic theory's transition towards hydrodynamic evolution, we systematically compare the out-of-equilibrium shear-stress tensor from KoMPoST-3D with estimates based on Navier-Stokes hydrodynamics. Subsequently, a comprehensive (3+1)D framework, McDIPPER+KoMPoST-3D+CLVisc+SMASH, is utilized to simulate the complete spacetime evolution of heavy-ion collisions. The sensitivity of key observables, including longitudinal structure of anisotropic flow, to variations in the hydrodynamic initialization time is thoroughly investigated.
↳ hep-phnucl-thPRD(2026)·3 citations
08
Nucleon Structure from Basis Light-Front Quantization : Status and Prospects
James P. Vary🇺🇸 · Chandan Mondal🇨🇳 · Siqi Xu🇺🇸 · Xingbo Zhao🇨🇳 · Yang Li🇨🇳
We review recent advancements in understanding nucleon structure within the Basis Light-Front Quantization (BLFQ) framework--a fully relativistic, nonperturbative approach to solving quantum field theories. In its initial phase, we start with the leading Fock sector $∣ q q q ⟩$ and an effective light-front Hamiltonian incorporating confinement and one-gluon exchange within which BLFQ can already successfully describe key nucleon observables. The framework has since been extended to include the next-to-leading Fock sector $∣ q q q g ⟩$ , enabling studies of gluonic contributions to the nucleon's internal structure, including gluon helicity, orbital angular momentum, and three-dimensional imaging through generalized and transverse momentum dependent parton distributions (GPDs and TMDs). Most recently, BLFQ has achieved a significant milestone by computing nucleon light-front wavefunctions as eigenstates of the QCD Hamiltonian without an explicit confining potential. These calculations, including Fock sectors up to $∣ q q q q q ˉ ⟩$ , further develop the path to first-principles predictions of quark and gluon matter densities, helicity and transversity distributions, and spin observables, showing qualitative agreement with experimental and phenomenological results. Together, these developments highlight BLFQ's growing capacity to provide an increasingly complete and realistic picture of nucleon structure grounded in QCD.
↳ hep-phhep-thnucl-thEur.Phys.J.ST(2026)·14 citations
09
$J / ψ$ -Meson Nucleon Scattering Length from Threshold Photoproduction on Light Nuclei
Igor I. Strakovsky (GWU)🇺🇸 · William J. Briscoe (GWU)🇺🇸 · Philipp Gubler (JAEA)🇯🇵 · Jackson R. Pybus (LANL)🇺🇸 · Axel Schmidt (GWU)🇺🇸 · Alexander Somov (JLab)🇺🇸
The quality of recent SRC/CT Collaboration $J / ψ$ photoproduction data off a $^{4}$ He target from Hall~D at Jefferson Laboratory, combined with the feasibility of measuring the reaction close to the free-nucleon energy threshold, opens the door to using incoherent $J / ψ$ photoproduction to access a variety of interesting physics aspects. An example is an estimate of the $J / ψ p$ scattering length $∣ α_{J / ψ p} ∣$ on the bound proton obtained using the Vector Meson Dominance model. This value can be compared with that of the free proton from the GlueX Collaboration. One may then project what would be expected from the SRC/CT Collaboration Experiment E12--25--002, which was recently approved by the JLab PAC. Using a plane-wave theoretical model to generate quasi-data, we find the experiment could achieve a result of $∣ α_{J / ψ p} ∣ = 3.08 \pm 0.45 mfm$ , an uncertainty competitive with that of the free-proton measurement. A comparison between the two would allow an evaluation of the effects of medium modification in the case of light nuclei.
↳ hep-phhep-exnucl-exnucl-thPRC(2026)·3 citations
10
The Radius of PSR J0437-4715 from NICER Data
M. C. Miller · A. J. Dittmann · I. M. Holt · F. K. Lamb · C. Chirenti · Z. Arzoumanian · J. Berteaud · S. Bogdanov · K. C. Gendreau · W. C. G. Ho · S. M. Morsink · P. S. Ray and 3 other authors
Neutron star Interior Composition Explorer (NICER) data have been used to estimate the masses and radii of the rotation-powered millisecond pulsars PSR J0030 $+$ 0451, PSR J0740 $+$ 6620, PSR J0437 $-$ 4715, PSR J1231 $-$ 1411, and PSR J0614 $-$ 3329, sometimes in joint analyses with X-ray Multi-Mirror (XMM-Newton) data. These measurements provide invaluable information about the properties of cold, catalyzed matter beyond nuclear saturation density. Here we present the results of our modeling of NICER data on PSR J0437 $-$ 4715 using several different models of hot thermal X-ray emitting spots on the stellar surface. For this pulsar, previous Nuclear Spectroscopic Telescope Array (NuSTAR) observations established that there is also a modulated nonthermal component to the emission, but the previously published analysis of NICER data did not model this component. We find that the Bayesian evidence is significantly higher when the modulated nonthermal component is included, and that omission of this component leads to poor fits to the bolometric NICER data and thus risks bias in the resulting radius estimates. Our models, which we pursue to inferential convergence, therefore have modulated nonthermal emission, and our headline model has in addition three uniform-temperature thermally-emitting circular spots. Using this model, the symmetric 68% credible range in the radius is 11.8 km to 15.1 km, which at the independently-measured mass of $M = 1.418 \pm 0.044 M_{⊙}$ is consistent with previous reports of the radius of the $\sim 1.4 M_{⊙}$ pulsar PSR J0030 $+$ 0451. We discuss the implications of this measurement for the equation of state of dense matter.
↳ astro-ph.HEgr-qcnucl-thApJL(2026)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE