Papers

About half of particle-bound nuclei have an odd number of nucleons. About one quarter more are odd-odd, meaning they have an odd number of neutrons and an odd number of protons. In this context, it is about time to shift the 70-odd-year focus of theories using nuclear energy density functionals (EDFs) away from the remaining one-quarter of even-even nuclei. This White Paper aims to present open, unresolved problems and promising research directions in nuclear EDFs that were discussed during the 2024 ESNT workshop in Saclay, France, on “The microscopic modelling of odd-mass and odd-odd nuclei”.

QCD calculations that use multihadron fragmentation functions usually involve multiple invariant mass scales simultaneously, with only one being the hard scale associated with an overall hard process. The other scales are associated with relative internal motion intrinsic to the fragmenting parton and the multihadron system. Nonperturbative contributions to this later type of dependence attract interest for their association with intrinsic partonic structures, but care is needed in disentangling the truly nonperturbative effects from perturbative behavior and relating the former to universal nonperturbative matrix elements. To this end, we show how to evolve collinear multihadron fragmentation functions in a way that accounts for the simultaneous presence of these extra scales. The general multihadron fragmentation functions evolve in the same way as ordinary single hadron fragmentation functions, with the dependence on the extra scales separated out. We use this to unify treatments of perturbative and nonperturbative effects in multihadron systems in a way that optimizes for interpretations focused on partonic structure.

A fast Monte Carlo code has been developed to calculate multiple neutron scattering in a sample. Good agreement with an independent Monte Carlo calculation using SAMMY is obtained for neutron capture in $^{197}$Au over the energy range 50–300 eV. For capture following two or more scattering events, a difference is found between the direct Monte Carlo calculation and the analytical approximation in SAMMY. The computational speed allows the scattering correction to be recalculated whenever trial resonance parameters are changed during parameter estimation. The computational core is implemented in C++, while data preparation, calculation control and analysis are performed in Python. Model studies examine how Monte Carlo statistics affect the accuracy with which neutron and radiative resonance widths are recovered.

At zero temperature, a dilute Fermi gas with an attractive contact interaction forms a superfluid with gapped fermionic excitations. We show that the gap at weak coupling can be organized as a trans-series expansion in the interaction strength and the asymptotic Gor'kov-Melik-Barkhudarov gap. Low-energy virtual quasiparticles generate corrections that are linear in the gap with a leading coefficient nearly 25$\times$ larger than the other known coefficients. This substantially increases the gap at intermediate densities, highlighting that systematic corrections are crucial for quantitative predictions.

We investigate excited-state effects in nucleon sigma-terms in lattice QCD using twisted-mass clover-improved fermion ensembles. We study correlation functions with nucleon and multihadron nucleon-$\sigma$-meson interpolating operators. The analysis is performed using three gauge ensembles, including one ensemble simulated with two degenerate light, a strange, and a charm quark with quark masses tuned to approximately their physical value. We solve the generalized eigenvalue problem that arises from the matrix of correlators and show that the three-point function for the light sigma-term obtained using the optimal linear combination of interpolating operators has substantially reduced time dependence without loss of statistical precision. We apply Laplace filtering and investigate residual excited-state contributions in the extraction of $\sigma_{\pi N}$. Using the same optimal linear combination of correlators as for $\sigma_{\pi N}$ for the strange sigma-term we also observe suppressed excited state contributions over an extended range of source–sink time separations. For the charm sigma-term, we observe negligible time dependence within the large statistical uncertainties, and these improvements show no significant effect.

We study short-range three-nucleon forces (3NFs) in nuclear lattice effective field theory with a chiral two-nucleon interaction at N${}^3$LO. The one-pion-exchange ($c_D$) and contact ($c_E$) terms of the leading 3NF are decomposed into locally and non-locally smeared components and supplemented by partial-wave-resolved pair contacts coupled to the density of a third nucleon. We determine their coefficients from nuclear binding energies for nuclei in the mass range from $A=3$ to $A=40$ and neutron–alpha finite-volume energies. This allows to work out the minimal three-nucleon force that can be used for future precision studies in NLEFT.

Characterized by central density depletion, bubble nuclei represent an important class of exotic nuclear structures. Collective flow in the $^{40}$Ca+$^{9}$Be projectile fragmentation reaction at 140 MeV/u is investigated using the extended quantum molecular dynamics (EQMD) model with a parameter on of the isoscalar monopole excitation strength $\varepsilon$. The projectile $^{40}Ca$ is initialized as a relaxed ten-$\alpha$ cluster configuration exhibiting a bubble-like density distribution. The results reveal that increasing $\varepsilon$ modifies the density distribution and the size of the depleted central region of bubble, producing pronounced changes in fragment yields and collective flow around $\varepsilon\approx0.5$. Below this value, heavy-fragment production plays a significant role, while the directed flow $v_1$ of protons and neutrons remains predominantly negative, indicating preferential emission toward the target side. Above $\varepsilon\approx0.5$, enhanced expansion of the central low-density region suppresses heavy residues and drives $v_1$ toward positive values. In contrast, preformed $\alpha$ clusters show different responses, reflecting their origin in the initial cluster configuration rather than solely in secondary decay. At low excitation, the cluster flow exhibits a pronounced impact-parameter dependence, whereas stronger excitation weakens cluster binding and suppresses directional anisotropy, driving the flow close to zero. The rapidity slopes of the flow coefficients also vary systematically with $\varepsilon$, tracing changes in emission anisotropy during expansion. These findings extend traditional static descriptions by probing the dynamical evolution of exotic structures in heavy-ion reactions and the contrasting collective-flow behavior of preformed clusters and single nucleons constitutes a sensitive dynamical probe of bubble-like structures.

The shell structure of nuclei beyond N=126 relevant to the third peak at A ~ 195 in r-process nuclear abundances in investigated. Within the framework of the relativistic Hartree-Bogoliubov theory in deformed space, a comparative study of the response of nuclei with three different model Lagrangians NL-SV1, SVI-2 and NL3 is made. Ground-state properties of even-even nuclei in the isotopic chains of Z=58-72$= in the highly neutron-rich region are investigated. A comparison of binding energies with mass formulas shows that in the extreme region of the r-process path, the RMF model SVI-2 without nonlinearities of sigma and omega mesons shows an excellent agreement with the mass formula HFB-24. It is shown that in all the above Lagrangian models, in the neutron rich region between the shell closures N=126 and N=184, there is a preponderance of nuclides exhibiting coexistence of well-deformed prolate and oblate shapes in the ground state. A prolate ground state is shown to evolve smoothly to a coexisting oblate ground state via a near degeneracy with successive addition of neutrons. Induced by an onset of deformation for $N \ge 130$, nuclei approaching the r-process path are shown to exhibit enhanced stability in many isotopic chains (Z > 60). This has the effect of shifting the expected neutron drip line significantly farther into the neutron-rich region especially for the higher Z chains. Consequences of the enhanced stability, the shape co-existence and degeneracy of shapes in nuclei on the r-process nucleosynthesis are discussed.

In this work, we calculate the binding energies of an equal-mass fermion–antifermion system in the $0^{-+}$ and $1^{--}$ channels from the ladder Bethe–Salpeter (BS) equation with scalar, pseudoscalar, and vector exchange. The results are compared with those of the Schrödinger equation with the corresponding leading static interaction in two regimes: pointlike massless exchange at weak coupling and finite-mass exchange with monopole form factors at stronger coupling. For the BS calculation, we use two independent numerical methods based on momentum-space integral equations and coordinate-space differential equations. The differential-equation method gives estimated relative binding-energy errors below $10^{-9}$ in both regimes. For massless vector exchange in Coulomb gauge, the numerical results are consistent with the uncrossed-ladder perturbative spectrum through the $O(m\alpha^5)$ terms. The results for massless scalar exchange and vector exchange in Feynman gauge are consistent with the common Wick–Cutkosky expansion through order $m\alpha^3$. For finite exchange masses, the differences from the leading static Schrödinger spectra at the same masses, couplings, and form factors depend strongly on the exchange and channel. Scalar exchange gives nearly degenerate channels with much weaker binding than the Schrödinger reference. In contrast, vector exchange with only the metric term retained gives stronger binding than the Schrödinger reference in $0^{-+}$ and weaker binding in $1^{--}$. Notably, retaining the full Proca numerator substantially increases the vector binding in both channels. Pseudoscalar exchange also supports bound states and favors $1^{--}$, although its leading static central interaction vanishes.

We revisit the extraction of parton distribution functions (PDFs) in the pion in a global QCD analysis of pion–nucleus Drell–Yan and leading-neutron (LN) electroproduction data, in view of recent suggestions that uncertainties on the pion PDFs at small parton momentum fraction $x$ are dramatically underestimated. We perform a set of controlled fits that vary the LN data coverage, PDF parametrization, and positivity constraints, determining both the PDFs and pion-nucleon splitting functions simultaneously. While the use of a restricted H1 LN data sample used by the Fantômas group is found to enlarge the PDF uncertainties and admit solutions with vanishing gluon PDFs, our global analysis provides a good description of an extended H1 and ZEUS LN database, significantly reducing the parametrization dependence and strongly disfavoring a zero gluon distribution.

We identify a strange-quark-number-dependent hierarchy in the response to explicit partonic dynamics by comparing PHSD5.2 with its hadron–string limit in baryon-rich Au+Au collisions at $\snn=3.0$–$7.2$~GeV. Crossing the local conversion threshold alone does not ensure a visible final-state signal: abundant-hadron flow changes little at 3–4.5~GeV, whereas the fractional yield response becomes ordered at 6.2–7.2~GeV, reaching $S_{|s|=1}\simeq0.2$–$0.3$, $S_{|s|=2}\simeq0.65$, and $S_{|s|=3}\simeq0.93$ at 7.2~GeV. The hierarchy is consistent with an enlarged recombination phase space for strange constituents released from different pre-hadronic sources, but does not by itself establish an increase in the total $s+\bar s$ abundance or stronger strange-quark clustering. Since $S_X$ is a model-defined response rather than a direct observable, matched excitation functions of $\Xi^-/\Lambda$ and $\Omega^-/\Lambda$, together with high-$m_T$ proton elliptic flow, provide experimentally accessible discriminants between the predicted PHSD and HSD dynamics.

Inferring the possible existence and location of a critical point on the QCD phase diagram through experimental observations requires equations of state that include both lattice QCD constraints and critical behavior. In this manuscript, we present the first four-dimensional equation of state in the $(T,\mu_B,\mu_Q,\mu_S)$ space combining the lattice 4D $T^\prime$-Expansion Scheme with a critical contribution mapped from the 3D Ising model. We extend the earlier two-dimensional construction, the so-called Ising 2D-TExS in the $(T, \mu_B)$ plane, promoting the critical point to a parametrizable critical surface in the full four-dimensional thermodynamic space. Our framework provides a family of equations of state to systematically study the effects of criticality in realistic hydrodynamic simulations with $BQS$ conserved charges, going beyond the case of strangeness neutrality, by varying the geometry of the critical surface and the strength of criticality at finite $\mu_B$, $\mu_Q$ and $\mu_S$ separately.

We investigate dilepton production via virtual quark bremsstrahlung in a hot, magnetized quark-gluon plasma (QGP), extending the Landau-Pomeranchuk-Migdal (LPM) framework to account for a background magnetic field and for Fermi-Dirac quark statistics. An external electromagnetic field drives the quark distribution out of equilibrium, and this off-equilibrium correction, obtained from the Boltzmann equation in the relaxation-time approximation, is in principle explicit in the electric and magnetic field strengths. We argue that this correction, being linear in the electric field, vanishes identically upon integration over the full dilepton solid angle and therefore does not contribute to the dilepton production rate (DPR). The leading magnetic-field signature in the rate instead enters entirely through the equilibrium sector: the medium density and Debye screening mass, computed from the Landau-level structure of the magnetized QGP, modifying the LPM suppression parameter. Working in the regime relevant to the hydrodynamic phase of heavy-ion collisions, we present the LPM-induced DPR for quark scatterers and establish, for the first time, a nonzero magnetic-field imprint on this observable through the LPM mechanism.

In this work we incorporate thermal fluctuations into fluid-dynamic simulations with the vHLLE code, in linear approximation. The fluctuations are built in following the fluctuation-dissipation theorem. The effect of space discretization into cells in numerical hydrodynamics on the spatial correlation of fluctuations is studied with the help of static structure factor. A difference from the continuum result is pointed out and systematically investigated. Time evolution of the ensuing fluctuations is examined and the Green-Kubo formula is used for the extraction of shear viscosity from the fluctuations. The extracted value is demonstrated to be the same as the input value of the shear viscosity for the simulations using Israel-Stewart equations. It is also shown that numerical regulators commonly used in the codes to ensure stability of the calculation severely spoil the fluctuations and break the fluctuation-dissipation theorem.

Three-dimensional femtoscopy probes the space-time structure of particle-emitting sources in relativistic heavy-ion collisions. The collision-energy dependence of Lévy source parameters may reveal the evolution of strongly interacting matter and possible signatures of the QCD phase diagram. We previously studied the excitation function of three-dimensional Lévy source parameters for pion pairs in Au+Au collisions with EPOS4, analyzing the pair-distance distribution \(D(\rho)\) through one-dimensional projections. Here, we analyze the full three-dimensional source distribution and correlation function directly. We construct \(D(\rho_{\rm out},\rho_{\rm side},\rho_{\rm long})\) as a 3D histogram, transform it into \(C(q_{\rm out},q_{\rm side},q_{\rm long})\) using a Fast Fourier Transform, and fit the correlation function with the analytic Lévy formula. This approach can reduce biases arising when one-dimensional projections are used to describe a non-elliptical source. We apply the method across the RHIC Beam Energy Scan range and compare the extracted energy dependence with results from the projection-based method and recent UrQMD calculations. We focus on the out-side observables \(R_{\rm diff}^{2}=R_{\rm out}^{2}-R_{\rm side}^{2}\) and \(R_{\rm out}/R_{\rm side}\), whose different energy dependences in EPOS4 and UrQMD may illuminate the roles of emission duration and source dynamics. This work establishes a direct three-dimensional framework for comparison with future femtoscopic measurements and for exploring possible non-monotonic structures associated with the QCD phase diagram.

An efficient method to exactly compute the adiabatic time-dependent Hartree-Fock-Bogoliubov collective vibrational inertias typical of fission is proposed. The method uses the quasiparticle finite amplitude method to invert the stability matrix of linear response. A comparison with other approaches, such as the exact generator coordinate method inertia and the associated cranking non-perturbative approximation, is conducted. It is found that the behaviour as a function of the collective variable (mass quadrupole moment) is essentially the same in the four cases considered, and substantially differs from the commonly used perturbative approach. It is also found that the magnitudes of the inertias are to a good extent related by single factors that seem to be connected with the effective mass of the energy density functional used.

We extend the quark mean-field (QMF) model to finite temperature and systematically investigate the thermodynamic properties of uniform nuclear matter, using the relativistic mean-field (RMF) model as a reference. For each model, we consider two parameter sets calibrated to the same selected nuclear-matter saturation properties but with different nucleon Dirac effective-mass ratios at saturation. We examine the effective nucleon mass and the composition of $\beta$-equilibrium matter, together with the free energy, energy density, pressure, entropy, and heat capacities of symmetric nuclear matter, pure neutron matter, and $\beta$-equilibrium matter. The QMF and RMF models exhibit similar qualitative trends, but their predictions increasingly differ at high density, where the effective masses have distinct density dependences. These differences are particularly evident in the thermal pressure and thermal index. For the two parameter sets considered in this work, we further provide compact analytical representations of the thermal index, $\Gamma_{\rm th}(\rho_{\rm b},T,\beta)$ over baryon densities of 0.08-1.0 $\rm fm^{-3}$, temperatures of 5-100 MeV, and isospin asymmetries of 0-1. The fits reproduce the numerical results with an accuracy better than $2\%$ and can be directly implemented in binary neutron-star merger simulations. This study establishes a finite-temperature extension of the QMF framework and provides a basis for future assessments of how a quark-structure-based description of nuclear matter affects thermal support and post-merger dynamics in binary neutron-star mergers.

The $x^2$ moment of the genuine twist-3 component of the unpolarized scalar parton distribution function $e(x)$ is related to the average transverse color Lorentz force experienced by a transversely polarized quark in an unpolarized nucleon. This higher-twist quantity probes quark–gluon correlations and provides unique insight into the nonperturbative dynamics of quantum chromodynamics. For the first time, we study the corresponding off-forward matrix element and derive its Lorentz-covariant decomposition in terms of generalized form factors. We calculate these form factors from light-front wave functions obtained by solving the light-front Hamiltonian eigenvalue problem within the Basis Light-Front Quantization framework. Their Fourier transforms provide a spatial picture of the transverse color forces in impact-parameter space. In particular, $\mathscr{F}_2$, whose forward limit is directly related to the twist-3 matrix element $e_2$, can be interpreted as the impact-parameter-space representation of the Boer–Mulders force, providing an intuitive spatial picture of the final-state interaction mechanism underlying the Boer–Mulders effect.

We propose a Lorentz-covariant on-shell formalism for allowed nuclear beta decay. Nuclear matrix elements are organized in a systematic effective field theory expansion in the recoil momentum, with the dependence on nuclear spin and polarization encoded in little-group-covariant structures. In this language, we construct the most general standard and exotic currents for allowed transitions through first recoil order. We then derive the differential decay distribution encoded in a set of Lorentz-invariant form factors. Specializing to the rest frame of the parent nucleus, we relate our parameters to those used in the traditional beta-decay literature and in nucleon- and quark-level effective field theories. The formalism provides a natural framework for extensions to higher recoil orders, radiative corrections, and forbidden transitions.

The formation of the evaporation residues in the $^{30}$Si$+^{186}$W reaction leading to the compound nucleus $^{216}$Ra$^*$ has been studied in the framework of the dinuclear system (DNS) model. The capture, complete fusion, quasifission, and incomplete fusion cross sections have been calculated at the collision energies $E_{c.m.}=107.6-172.2$MeV by averaging over the orientation angles of the axial symmetry axes of the deformed $^{30}$Si and $^{186}$W nuclei. The incomplete fusion is considered as the breakup of the DNS with the emission of the $\alpha$ particle from its very mass-asymmetric configuration, which is populated by the nucleon transfer in collisions with large orbital angular momentum. The survival probabilities of the excited $^{216}$Ra and of the conjugate nucleus $^{212}$Rn formed after the $\alpha$-particle emission have been calculated using the statistical model. It is shown that the complete fusion is the main source of the evaporation residues at the lower collision energies, while above $E_{c.m.}=128$MeV the Rn isotopes formed in the incomplete fusion give more than half of the calculated evaporation residue cross section. The sum of both contributions describes the slow decrease of the measured total evaporation residue cross section at these energies, where the yield of the Ra isotopes decreases by an order of magnitude. The calculation of the de-excitation of $^{216}$Ra$^*$ with the emission of protons and $\alpha$ particles shows that the contribution of the complete fusion to the cross sections of the isotopes $^{212}$Rn and $^{211}$Rn is negligible, and these isotopes are formed in the incomplete fusion. The fusion probability calculated for the partial waves $\ell\leq30\hbar$ is about 0.75 in comparison with the value $0.57\pm0.08$ extracted from the experimental data at the same collision energies.

In spin-$3/2$ targets, octupole polarization can reveal quark and gluon correlations beyond those probed by vector polarization and quadrupole alignment. Here, we construct the complete leading-twist gluon transverse-momentum-dependent distribution basis, with 32 independent coefficients for each specified Wilson-line and color structure. Fourteen of these describe octupole dependence in gluon number, helicity, and linear polarization. In heavy-quark-pair leptoproduction at small, nonzero pair imbalance, comparing target states with opposite octupoles and identical lower moments isolates the octupole contribution. Beam-helicity reversal and joint angular projections in target orientation and pair-imbalance azimuth can then separate all fourteen gluon octupole responses at leading-power Born order. We also derive the incoming-target quark responses in semi-inclusive deep-inelastic scattering and Drell-Yan production. Time-reversal relations between distributions remain valid under symmetry-preserving renormalization and evolution, while predictions across processes require factorization formulas connecting those distributions to scattering observables. Finally, we connect this framework to polarized $^{7}$Li through its collinear limits and nuclear spin-orbital correlations.

We study thermodynamic consistency and stability in a covariant two-flavor nonlocal Nambu–Jona-Lasinio model at zero chemical potential in the homogeneous quark mean-field approximation. A controlled large-source expansion gives a sufficient entropy-sign criterion directly from Euclidean kernel moments, without locating propagator poles. At fixed couplings and kernel, every admissible positive Gaussian mixture develops negative total entropy at sufficiently large source mass for each fixed positive temperature. In a separate light-source fit to pion observables and a subtracted condensate, one quartic-exponent kernel has positive entropy and heat capacity for all $T>0$, while $dP/d\epsilon=s/C_V$ exceeds unity on a finite interval. This constructive example separates thermal positivity from the static EOS slope test. Numerical refits show that the enhancement weakens with the condensate input, and a certified counterexample excludes uniform thermal positivity over the adopted matching domain. The results provide diagnostics of the mean-field functional, rather than a preferred phenomenological kernel. Omitted thermal mesons can change the low-temperature slope test, and the static derivative does not determine a real-time front velocity.

We present the new CTEQ-JLab global QCD analysis, called CJ26, that simultaneously fits parton distribution functions of the proton and nuclear effects in deuteron targets. This work includes, for the first time in a global fit, the full set of JLab 6 GeV inclusive DIS measurements and the first published JLab 12 GeV data. The analysis focuses on the large-$x$ region, and carefully treats the interplay between higher-twist effects and off-shell corrections in low-energy proton and deuteron target data. We discuss their effect on quark and gluon distributions, and highlight the importance of quantifying the experimental correlated systematic uncertainty to achieve fits of the highest accuracy. We also outline how upcoming data may help unravel the nuclear and partonic dynamics in light nuclei. The extracted next-to-leading order parton distributions are available on the CJ web pages in LHAPDF format for general use, accompanied by leading- and higher-twist structure functions calculated with the simultaneously fitted PDFs, higher-twist corrections, and off-shell corrections. This write up clarifies several points that became clearer while finalizing the CJ26 paper and can be read as a companion to the latter.

The question of the link between the nucleon properties and the equation of state of ultra-dense matter, both being composed of quarks and gluons, is investigated by adopting a soliton model to describe internal nucleon properties and a direct mapping between nucleon and quark matter to obtain the equation of state of ultra-dense matter. We compare $\pi+\omega$ and $\pi+\omega+\rho$ soliton models and analyze the presence of a pressure singularity at the nucleon center due to the $\rho$ field. This singularity impacts the equation of state in ultra-dense matter. Only the pressure derived from the canonical energy-momentum tensor has a singularity, while the Belinfante pseudo-gauge transformation of the energy-momentum tensor generates an internal pressure without a singularity. We then investigate predictions for the equation of state of ultra-dense matter based on different prescriptions for the nucleon pressure. It is shown that none of the prescriptions agree with the thermodynamical pressure defined in uniform matter. The mismatch between any equation of state and the thermodynamical one questions the simplicity of the direct mapping between finite-size nucleon properties and uniform matter as well as the role of the nucleon surface in the internal energy density and the pressure.

Using continuum Schwinger function methods, we deliver parameter-free pointwise predictions for the complete set of twelve Standard Model (SM) $\bar B_{(s)} \to D_{(s)}^{(\ast)}$, i.e., $b\to c$, semileptonic transition form factors on the entire kinematically accessible domain. Therewith, we calculate SM theory values for the decay-rate ratios of $\tau$ and $\mu$ final states: $\{ R(D) \, , \, R(D)^\ast \} = \{ 0.290(11) \, , \, 0.267(5) \}$, $\{ R(D_{s}) \, , \, R(D_{s}^{\ast}) \} = \{ 0.283(11) \, , \, 0.251(5) \}$. The former is consistent with an existing average of SM estimates, but disagrees with the experimental average by $2.8\sigma$. Comparing transitions with light quark and strange quark spectators, we find a $2.3\sigma$ signal for violation of SU$(3)$ flavour symmetry, expressed at the 5% level in $D_{(s)}^\ast$ final states. It is induced by Higgs boson couplings into the strong interaction and modulated by phenomena deriving from emergent features of the strong interaction.

Universal, equation-of-state (EOS) insensitive relations among the global properties of compact stars are well established for hadronic neutron stars and for self-bound strange stars. We ask whether analogous relations hold for the quark core of a hybrid star, and whether the core can be constrained from the surface. Describing quark matter with the three-flavor MIT bag model with repulsive vector interactions, matched to the hadronic DD2 EOS through a Maxwell construction, we scan the full $(B^{1/4},G_V)$ plane and obtain 1112 hybrid EOSs with maximum masses above $2\,M_\odot$, broadly compatible with current multimessenger constraints. For every stable configuration we evaluate the mass, radius, moment of inertia, and tidal deformability both at the stellar surface and at the boundary of the quark core. Global quantities follow the relations of hadronic stars—the $I$–Love relation to within $0.5\%$—while core quantities follow those of self-bound strange stars with median deviations of $6$–$9\%$. We explain the latter by expanding the structure of the core in powers of its compactness: to first order, the core mass, baryon mass, moment of inertia, and tidal deformability depend only on the compactness and on the properties of the hadron–quark interface, chiefly the ratio $\xi=p_{\rm tr}/\varepsilon_+$ of transition pressure to quark energy density. The strange-star relations are the $\xi\to0$ member of this family, and the deviations from them measure $\xi$. The fractional core mass and radius of all configurations follow the normalized mass profile of the star, and no global observable allows the core size to be inferred. Evanescent cores dominate the viable parameter space, while sizable cores require low bag constants and strong vector couplings.

We study the coupled diffusion of baryon number, electric charge, and strangeness in hot and dense quark matter using a three-flavor Nambu-Jona-Lasinio model with self-consistently generated constituent quark masses. The complete diffusion matrix is evaluated within a relaxation-time kinetic approach, including its diagonal and off-diagonal components. We find that the off-diagonal transport coefficients exhibit distinct temperature and baryon-chemical-potential dependence associated with the flavor-dependent composition of the charge carriers. We further investigate generalized charge diffusivities and mobilities obtained from the corresponding susceptibilities. At finite baryon chemical potential, the baryon and strangeness mobility scales cross, reflecting the different density dependence of their transport coefficients and susceptibilities. The results provide model benchmarks for coupled conserved-charge transport in baryon-rich QCD matter.

The adiabatic distorted-wave approximation (ADWA), the standard model for deuteron stripping and pickup, depends on the neutron-proton interaction through the form factor $V_{np}\phi_d$. With nonlocal nucleon potentials, the neutron-proton kinetic energy averaged with this form factor shifts the energy at which the nucleon-target potentials are evaluated, and ADWA cross sections become sensitive to the choice of interaction. I ask whether this sensitivity reflects short-range neutron-proton structure. A unitary transformation of the neutron-proton Hamiltonian with the AV18 interaction, confined to short distances, represents the same interaction differently and preserves the two-body scattering matrix, the deuteron binding energy, and both asymptotic normalizations. It raises the weighted kinetic energy from 218 to 313 MeV, a change equal to more than half the range spanned by the five realistic interactions studied, while the finite-range coefficient, which controls low-momentum transfer, hardly moves. The weighted kinetic energy is dominated by the variance of the kinetic energy, which the high-momentum components control, whereas the finite-range coefficient is set by the spatial extent of the form factor. A dependence on $V_{np}$ carried by the weighted kinetic energy can therefore arise from the representation of the interaction alone, and does not by itself measure its short-range content.

We examine the impacts of dark matter (DM) on the observables of the neutron star (NS). The interaction of DM with nucleons intermediate by axion-like particles (ALPs), and the DM-admixed NS (DNS) is formulated in the framework of the relativistic mean field (RMF) formalism. The effects of the DM on the NS are characterized by two parameters: DM Fermi momentum ($q_f$) and DM mass ($m_\chi$). By varying these two parameters, we investigate how the NS's mass, radius, and tidal deformability are altered. Furthermore, we study how the ALP-mediated DM impacts the stability of the NS through the analysis of radial oscillations. In addition, the nonradial oscillation has been investigated by calculating its fundamental mode frequency in the DNS and analyzed how the ALP-mediated DM modifies its behavior.

We derive the covariant equations of nondissipative chiral hydrodynamics from their equal-time Hamiltonian formulation and identify the Lie–Poisson structure implicit in the chiral brackets. This structure combines fluid motion with local chiral transformations. For a parity-invariant Hamiltonian quadratic in chiral charge densities and pion gradients, without external backgrounds, we derive and solve the constraints imposed by Lorentz boosts. Their coupled nonlinear sector is equivalent to the linear boost transformation laws of a symmetric tensor, which determine the velocity dependence from rest-frame data. For finite, positive rest-frame coefficients, finite ordinary-fluid energy density and thermodynamic derivatives, and a momentum–velocity relation that can be solved in either direction, the chiral Hamiltonian coefficients remain finite at every fluid speed below light speed if and only if the rest-frame pion propagation speed does not exceed the speed of light. This formulation makes symmetry constraints explicit and provides a starting point for future thermodynamically consistent dissipative extensions.