Papers

In this paper we investigate accelerated gluodynamics for a broad intervals of temperature and acceleration. Our study is carried out within lattice simulation in the co-moving reference frame parameterized by the Rindler coordinates. We developed the renormalization prescription that allowed us to calculate renormalized Polyakov loop as a function of coordinate in the Rindler spacetime. Using the data for the renormalized local Polyakov loop, we calculated spatial dependence of the static quark free energy and effective mass of static quark. Besides the Rindler coordinates, it is believed that accelerated gluodynamics can be approximated utilizing non-accelerated gluodynamics with a properly adjusted temperature gradient in accordance with the Tolman-Ehrenfest law. We compared these approaches for the observables under study. It was found that they agree quite well close to the critical temperature and demonstrate disagreement at higher temperatures. We believe that this disagreement might be attributed to the Tolman-Ehrenfest law corrections which appear in the Rindler gluodynamics.

We analyze the impact of rotation on the chiral crossover transition of QCD matter within the framework of a hadron resonance gas model. By extending the conventional formulation of the renormalized chiral condensate to a rotating hadronic medium, we find that rotation significantly modifies the chiral condensate and systematically suppresses the pseudocritical temperature as the angular velocity increases. The pseudocritical line in the $T-\omega$ plane is examined, and the rotational dependence of the pseudocritical temperature is quantified through leading- and next-to-leading-order rotational curvature coefficients. We further investigate the combined effects of angular velocity and baryon chemical potential and find that their interplay leads to a stronger suppression of the pseudocritical temperature. Additionally, the spatial dependence of the chiral crossover transition is examined through the radial variation of the pseudocritical temperature. We find that the pseudocritical temperature decreases with increasing radial distance, indicating that the chiral crossover sets in at progressively lower temperatures as one goes away from the rotation axis.

We investigate gluon saturation effects in semi-inclusive deep inelastic scattering (SIDIS) at small-$x$ within the Color Glass Condensate framework. We compute the SIDIS cross section at leading order in the dipole picture, expressing it in terms of the dipole-target scattering amplitude. We validate our framework by comparing with the charged hadron spectra measured at HERA. Our predictions for the EIC indicate that saturation effects result in significant nuclear suppression in the SIDIS cross section, and can provide complementary constraints on the initial condition for the Balitsky-Kovchegov evolution extracted from inclusive DIS data. These results demonstrate that SIDIS measurements at the EIC are sensitive to nonlinear QCD dynamics in the saturation regime.

The $\gamma Z$-box correction is an important electroweak contribution to precision parity-violation measurements, but its conventional low-energy treatment relies on an ambiguous effective quark-mass prescription. We revisit this correction using a finite-mass calculation that provides a well-defined perturbative contribution without introducing such an auxiliary scale. Applying the result to the Jefferson Lab PVDIS measurement shifts the extracted electron-quark couplings at the $10^{-3}$ level. We discuss the implications of this shift for precision electroweak tests and the need for a consistent separation of perturbative and non-perturbative hadronic contributions.

The precision of the electromagnetic proton-neutron mass difference $\delta m_\mathrm{QED}$ extracted from the Cottingham formula hinges on a subtraction function whose low-energy normalization $\bar S(0)$ is fixed by the isovector combination of the proton and neutron polarizabilities, $(\alpha_{E1}-\beta_{M1})^{p-n}$. We derive a dispersive sum rule for this combination in terms of $s$-channel photoabsorption cross sections and the product of $t$-channel $\gamma\gamma\to\pi\eta/K\bar K_{I_t=1}$ and $\pi\eta/K\bar K_{I_t=1}\to N\bar N$ amplitudes, without invoking Reggeon dominance. Combining empirical pion-photoproduction multipoles with coupled-channel Muskhelishvili–Omnès representations of the scalar-isovector $\pi\eta/K\bar K$ amplitudes, we obtain $(\alpha_{E1}-\beta_{M1})^{p-n}=-2.26(73)\times10^{-4}\,\mathrm{fm}^3$, fixing its sign and reducing the uncertainty by a factor of 4 compared with the previously known value. This result yields $\bar S(0)=-1.76(61)\,\mathrm{GeV}^{-2}$, leading to $\delta m_\mathrm{QED}=0.71^{+0.03}_{-0.06}\,\mathrm{MeV}$, substantially more precise than previous Cottingham determinations. The negative $\bar S(0)$ also provides a stringent low-energy test of Reggeon dominance in the subtraction function.

We report on our study of inclusive neutral-kaon photoproduction on the deuteron, $d(\gamma,K^0)YN$, for photon energies between 0.9 and 1.1 GeV. The calculation is performed in the impulse approximation, with the deuteron wave function generated from the Bonn One-Boson-Exchange-Potential in $q$-space (OBEPQ) within a non-relativistic framework, while the kinematics and the elementary operator are kept relativistic. For the elementary operator we employ a recently developed isobar model that includes high-spin nucleon and $\Delta$ resonances and has been constrained by nearly 20,000 data points, and we compare its predictions systematically with those of the Kaon-Maid model. For the first time, the NKS1 and NKS2 data are subjected to a quantitative analysis within a modern elementary production framework. The New Operator provides a considerably better description of the data, whereas Kaon-Maid overestimates the measured cross section by up to a factor of four at the higher photon energies, a discrepancy that can be traced back to its unconstrained $\gamma n \to K^0\Lambda$ amplitude. We further show that the finite photon-energy and kaon-angle bins of the existing measurements generate a theoretical uncertainty comparable to the difference between the two models, so that a proper comparison with the data requires the calculation to be averaged over the experimental acceptance. A three-dimensional mapping of the cross section over the kaon momentum and angle reveals a narrow quasi-free ridge, accompanied by a second structure associated with the opening of the $\Sigma$ channels, from which we identify the kinematics most favorable for future measurements. Finally, the tensor target asymmetries are found to be far less sensitive to the elementary operator than the cross section, and therefore probe the nuclear dynamics in a way that is complementary to the cross section.

Equations of state (EoS) for dense matter are commonly provided in tabulated pressure-energy density relations, complicating numerical implementation and potentially compromising thermodynamic consistency. In this work, we propose a piecewise-continuous analytical form with a common parametrization capable of representing a broad class of dense matter EoSs. We validate this parametrization against tabulated EoSs from the CompOSE and LALSimulation repositories. Following the initial deterministic fitting, we employed two distinct Bayesian approaches: one based on synthetic EoSs generated by adding noise to the fitted EoS and another based on multi-messenger measurements of neutron-star masses and tidal deformabilities. In both approaches, the initial best-fit parameters are used as reference values. For the considered EoSs, spanning from very soft to very stiff, the resulting fits reproduce the tabulated EoSs and the associated macroscopic neutron-star observables in the repositories with sufficient accuracy. The inferred parameters exhibit strong correlations arising from the continuity conditions imposed at the segment boundaries. These correlations persist in the low- and intermediate-density segments under multi-messenger inference but become weak in the core, reflecting the limited constraining power of current observations at high densities. The ability of a single functional form to describe EoSs derived from different microscopic frameworks, together with the recurrence of similar parameter correlations, suggests that diverse dense matter EoSs may share a common underlying structure.

The hypothesis of strange quark matter (SQM) and the possible existence of strange stars have been extensively investigated within the thermodynamic bag model, typically employing the free Fermi gas approximation with or without perturbative QCD corrections at zero temperature, where quark confinement is modeled by the bag pressure. In this work, based on the perturbative inclusion of quark mass effects, we develop a thermodynamically consistent equation of state (EOS) for SQM at finite temperature, incorporating perturbative corrections up to $\mathcal{O}(\alpha_s)$ in the strong coupling constant $\alpha_s$ while ensuring full adherence to the Maxwell relations. These corrections are essential for accurately describing hot quark stars potentially formed during core-collapse events. We present results for both fixed and running couplings, using a phenomenological model to include the breakdown of the perturbative running of $\alpha_s$ at low momenta. Our results demonstrate that incorporating finite-temperature perturbative QCD corrections leads to SQM configurations that fall within the absolute stability window, with equilibrium energies per baryon lying below that of iron, the most tightly bound nucleus. Our EOS supports compact stars with masses exceeding $1.4\,M_\odot$ (and above $2\,M_\odot$ for some values of the bag constant), in agreement with current astrophysical constraints from pulsar and gravitational-wave observations.

[Abridged] In this work, we compare neutron stars where dark energy or dark matter are present in the core, contrasting them against purely baryonic stars with the same central energy density. From this comparison, we find that the dark energy models are more constrained by neutron star observations than the dark matter models, suggesting that neutron stars can place strong constraints on dark energy parameters. We consider four configurations: purely baryonic neutron stars described by a piecewise polytropic (PP) equation of state (EoS), baryonic stars admixed with bosonic or fermionic asymmetric dark matter (ADM) cores, and stars with a dark energy core and baryonic shell, where the dark energy is described by the modified Chaplygin dark fluid (MCDF). Using the masses and radii of PSR J0740$+$6620, PSR J0437$-$4715, and PSR J0030$+$0451, we employ Bayesian inference to investigate how accounting for bosonic/fermionic ADM and MCDF cores affects the inferred neutron star properties. We find that MCDF cores, more than PP and ADM admixed models, substantially broaden neutron star mass-radius and pressure-energy density posterior distributions. Moreover, the MCDF EoS parameters can be tightly constrained. While bosonic and fermionic ADM cores decrease the inferred maximum mass, their posteriors strongly coincide with those of the PP model for ADM mass-fractions $F_\chi \leq 5\%$. These results demonstrate that current mass-radius observations cannot rule out MCDF cores, but they can constrain the MCDF parameter space to narrow regions. ADM admixed neutron stars, however, remain observationally identical to purely baryonic stars for all explored mass-fractions, even with improved mass-radius uncertainties. This suggests that mass-radius measurements alone are insufficient to detect ADM core inside neutron stars and that independent astrophysical or particle physics probes will be required.

A first-principles investigation of heavy-light meson behaviour in hot QCD matter is essential for the interpretation of experimental results associated with open heavy flavour productions in relativistic heavy-ion collision experiments. Using anisotropic lattice ensembles from the FASTSUM collaboration with Nf=2+1 dynamical Wilson-clover fermions at non-zero temperatures, we study the B and B_s spectra at non-zero temperature. We use relativistic light quark propagators, while the b quark propagators are computed with a non-relativistic effective theory (NRQCD). We find that above T_c, thermal effects on the B meson states are more significant than those on the B_s states. Also, our results support the dissolution of the B-meson bound states above T_c.

We present a systematic framework to extract QCD thermodynamic properties at finite baryon density from ultra-central heavy-ion collisions, where the impact parameter is nearly zero and volume fluctuations are strongly suppressed. By mapping the measured multi-particle state of each event to an effective homogeneous fireball through the conservation of total energy, total entropy and net baryon number, a near-thermal state with variations is realized from event to event, which allows thermodynamic response relations to be tested. Using STAR Beam Energy Scan data on charged particle multiplicity and net proton fluctuations, we show that the thermalization condition is satisfied within uncertainties across collision energies, validating the interpretation of ultra-central events as small deviations from a thermally equilibrated state. We then generalize the response relations to finite baryon chemical potential, expressing the response coefficients in terms of the speed of sound and susceptibilities. Our results provide a baseline for using ultra-central collisions to probe the QCD equation of state and phase structure, including the search for the critical endpoint.

In this review we give an overview about dileptons as probes for the properties of the strongly interacting hot and dense matter created in heavy-ion collisions at various beam energies. As penetrating probes they leave the fireball unaffected from final-state interactions and thus provide a space-time-evolution weighted average of the in-medium properties of hot and dense QCD matter.

This is the second of two papers discussing a new experimental signature of mixed-symmetry states (MSS) in the vibrational nuclei $^{92,94}$Zr and $^{94}$Mo based on proton and neutron transition densities. Quasiparticle-phonon model calculations for these nuclei are extensively tested by comparison to ground-state properties, energies and moments of excited states, transition probabilities between them, and the momentum transfer dependence in $(e,e^\prime)$ and $(p,p^\prime)$ reactions. The overall very good agreement permits the extraction of information on the wave functions of the MSS and their fully symmetric (FSS) counterparts. MSS can be identified by a sign change between the leading proton and neutron two-quasiparticle configurations compared to the FSS. Possible candidates for $2^+$, $3^-$, and $4^+$ MSS are identified. The modification of proton and neutron transition densities, which can be derived from a combined analysis of inelastic electron and proton scattering, by the sign change provide a new experimental signature of MSS. The collectivity of ground-state excitations of predominantly one-phonon FSS and MSS is generated to a large extent by the coupling to high-lying states forming giant resonances with the same spin and parity.

Nuclear masses are fundamental quantities in nuclear physics, providing essential information for understanding nuclear structure, decay properties, and reaction processes. Here we develop a bidirectional recurrent neural network (Bi-RNN) that naturally incorporates sequential correlations along isotopic and isotonic chains for nuclear mass prediction. The model achieves a root-mean-square (rms) deviation of 78 keV for binding energies of 2339 nuclei with known masses, a 45% improvement over a conventional artificial neural network (ANN) with comparable parameter count. The Bi-RNN also delivers consistent accuracy across different odd-even parity groups and yields an rms of 99 keV for $Q_\beta$ values without explicit training, demonstrating that recurrent correlations encode physically relevant information beyond individual nuclear features. Extrapolation tests on 292 nuclei updated from AME2003 to AME2012 and on 109 nuclei updated from AME2012 to AME2020 reveal that the Bi-RNN maintains stable performance, substantially outperforming WS4, ANN, and earlier AME evaluations. These results demonstrate the power of recurrent architectures in capturing correlations along nuclear chains and suggest Bi-RNN as a robust tool for studying nuclear masses.

Nuclear landscape is initially explored in the framework of relativistic Hartree-Bogoliubov theory under the spherical approximation, adopting the newly developed PCF-PK1 density functional. The functional effectively incorporates exchange terms via the Fierz transformation and explicitly includes the tensor coupling. We analyze the limits of the nuclear landscape and nuclear ground state properties including binding energies, charge radii, {\alpha}-decay energies, compared with other functionals and experiment. In the present calculations, 7210 nuclei are predicted to be bound with the root-mean-square deviation of binding energies 7.170 MeV. The removal of spurious shell closure at Z = 58 and 92 is discussed by shell gaps and single-particle spectra. For superheavy nuclei, potential magic numbers beyond 208Pb are studied. The inclusion of the tensor coupling in PCF-PK1 helps restore the pseudospin symmetry, leading to a less pronounced shell closure at Z = 120.

Background: The nuclear tensor force couples the spin and orbital degrees of freedom, thereby generating spin-orbital (SO) entanglement. This interaction also induces spatial anisotropy of density distributions. While the tensor force underlies both phenomena, the direct connection between them remains unclear. Purpose: We clarify the quantitative relationship between the SO entanglement and spatial anisotropy of the deuteron. This system provides a fully analytical description of both features. Methods: We quantify the SO entanglement by the entanglement entropy and spatial anisotropy by the Kullback-Leibler (KL) divergence. Their evolution is traced by continuously varying the $S$-$D$ coupling in the deuteron. Results: We derive analytical expressions for the entanglement entropy and KL divergence, both of which depend on $M$, the projection of the deuteron total angular momentum $J=1$. The stronger the tensor-force-induced $S$-$D$ coupling is, the larger both the entanglement entropy and KL divergence become. Conclusions: The analytical results and the positive correlation between the two quantities clearly demonstrate that the two features stem from the same underlying coupling mechanism governed by the algebraic structure of the deuteron wave function.

Background: The generation of spin distributions in fission fragments has attracted substantial interest in recent years and its mechanism is becoming clear alongside the refined description with microscopic theories. In contrast, the microscopic origin of spin distributions in reaction products remain largely unexplored. Methods: Three-dimensional TDHF calculations are performed for multinucleon transfer processes in the $^{40}\text{Ca} + {}^{124}\text{Sn}$ reaction at $E_{\text{c.m.}} \simeq 128.54\,\text{MeV}$ using the Skyrme SLy5 energy density functional. To obtain spin distributions in each transfer channel, the particle-number projection (PNP) and the angular-momentum projection (AMP) are simultaneously achieved for a reaction product. Results: By performing PNP+AMP for TDHF wave functions after collisions, spin-dependent transfer cross sections are calculated for projectile-like fragments (PLFs). From the results, we find that abundant spin distributions can be obtained from the TDHF wave functions. For one-nucleon addition and removal channels, the calculated spin values agree well with those of single-particle states in the $pf$- and $sd$-shell, respectively. Moreover, for a-few-nucleon transfer channels, we show that the obtained spin distributions can be well explained by combinations of total angular momenta of those single-particle states. Furthermore, as the number of transferred nucleons increases, we find that the calculated spin distributions exhibit a smooth singly-peaked shape with a long tail as a function of $J$, which resembles that of empirical spin distributions for thermally equilibrated fragments. An exploratory calculation for induced fission of $^{240}$Pu is also carried out, obtaining similar results as in multinucleon transfer reactions. (shorted due to the arXiv's word limit)

Spin correlations are believed to contribute significantly to vector-meson spin alignment. In this work, we study the generation of spin correlations through fluctuations of the chromomagnetic field in the quark-gluon plasma. We show that anisotropic fluctuations generically lead to finite vector-meson spin alignment. We study two sources of anisotropic chromomagnetic-field fluctuations: one arises from the motion of a vector meson relative to the medium, which makes isotropic fluctuations in the medium anisotropic in the meson rest frame; the other arises from QGP shear flow through viscous corrections to the chromomagnetic field fluctuations. The linear HTL estimates indicate sensitivity to the nonperturbative magnetic sector; we treat the full field correlators as phenomenological inputs.We apply the mechanism to study spin alignment of $J/\psi$ in heavy ion collisions. With QGP evolution modeled by Bjorken flow, we obtain negative spin alignment from both sources, with the shear induced contribution numerically suppressed compared to the motion induced contribution.

Magnetars, neutron stars harboring the strongest magnetic fields known in the Universe, are associated with a broad range of observational phenomena, from giant flares to fast radio bursts, and have also been proposed as potential sites of heavy-element nucleosynthesis. These phenomena are thought to be closely linked to the structure and composition of magnetar crusts. The outer crust consists of fully ionized nuclei embedded in a degenerate electron gas, while the inner crust additionally contains free neutrons. We investigate how strong magnetic fields modify magnetar crusts, accounting for the spin polarization of free neutrons. Arising from the coupling between the magnetic field and the neutron magnetic moment, neutron spin polarization lowers both the pressure and matter density marking the boundary between the outer and inner crusts for magnetic field strengths $B \gtrsim 10^{17}~\mathrm{G}$. As a consequence, the outer crust becomes thinner, the formation of the superheavy nuclei predicted in previous studies is suppressed, and the neutron ocean permeating the inner crust becomes spin-polarized. These effects may have important implications for the diverse manifestations of magnetars and for $r$-process nucleosynthesis in the ejecta of magnetar giant flares.

Quantum machine learning has the potential to become a new tool for understanding complex nuclear structures. In this work, we apply a hybrid quantum convolutional neural network (QCNN) to nuclear charge-radius prediction for the first time, aiming to explore the feasibility of quantum machine learning in nuclear-physics data analysis. Based on a classical convolutional neural network (CNN) framework, a small variational quantum convolutional filter is introduced as a quantum feature map to extract local correlations on the nuclear chart. The QCNN shows promising predictive accuracy and training stability, and provides a reliable description of the charge-radius evolution along several representative isotopic chains. These results support further investigation of quantum convolutional architectures for nuclear-structure data analysis.

We propose an operator basis for the unpolarized deep-inelastic scattering (DIS) quark-antiquark dijet production process smoothly connecting the all-twist eikonal regime to the back-to-back leading-twist TMD regime at arbitrary Bjorken x. Starting from the background-field quark propagator we construct an operator basis that organizes the eikonal and twist expansions within a unified formulation. Utilizing this operator basis we derive the dijet production amplitudes retaining all contributions required by either the leading-eikonal or the leading-twist description. In the eikonal limit the resulting amplitudes reproduce the all-twist Color Glass Condensate result, while in the back-to-back limit they reduce to the leading-twist gluon TMD-based result at arbitrary x. The operator basis can be systematically extended to include sub-eikonal and higher-twist corrections. Further, by examining the relationship of this operator basis to the improved TMD (iTMD) factorization we recover the iTMD structure in the eikonal limit. However, we find at non-zero x the transverse resummation generates longitudinal phases that prevent factorization in terms of a conventional TMD operator.

We investigate the twist-2 and twist-3 tensor-polarized partonic structures of the spin-1 deuteron. Using the operator product expansion with local operators, we derive a Wandzura-Wilczek (WW)-like twist-2 relation between the tensor-polarized twist-2 quark distribution $f_{1LL}$ and the twist-3 distribution $f_{LT}$, together with a Burkhardt-Cottingham (BC)-like sum rule. The local-operator formalism makes the Lorentz structure and rotational invariance manifest and provides useful constraints on the twist-3 sector. We then use a phenomenological parametrization of the twist-2 distribution $f_{1LL}(x)$, constrained by HERMES data on the deuteron structure function $b_1$ at $Q^2=2.5~\text{GeV}^2$, to quantitatively estimate the twist-3 distribution $f_{LT}(x)$ within the WW approximation. The resulting $f_{LT}(x)$ has a shape and magnitude comparable to those of $f_{1LL}(x)$, indicating that subleading-twist effects may be relevant for future experiments at relatively low $Q^2$. In this contribution, we summarize the theoretical derivation of the WW-like relation and BC-like sum rule and present a phenomenological estimate of the tensor-polarized twist-3 quark distribution $f_{LT}$ in the deuteron.

The search for physics beyond the Standard Model in low-energy weak interaction processes requires a precise knowledge of the Standard Model background at tree- and loop-level. In many such cases, radiative corrections represent one of the major sources of theory uncertainty due to the non-perturbative structures of nucleon or nuclei. In this review, I discuss several modern strategies based on dispersion relation, lattice gauge theory and nuclear many-body calculations to pin down the hadronic and nuclear uncertainties in the radiative corrections to low-energy weak interaction processes such as beta decays and parity-violating electron-nucleus scattering.

The initial-state geometry plays a crucial role in driving directed flow, while the dissipative response of the medium dampens it. Both of these factors influence how the directed-flow slope varies with system size. We developed a method to differentiate between these driving and damping effects on charged-hadron directed flow in O+O, Cu+Cu, Ru+Ru, Au+Au, and U+U collisions at $\sqrt{s_{\mathrm{NN}}} = 200$~GeV using an improved version of the string-melting AMPT model. We formulated three scaling observables based on the entropy density, the number of participants, and the mass number. A dimensionless ratio was constructed, revealing the threshold mass number $A \approx 35$ in central collisions from the entropy and participant scaling, indicating the onset of collective behavior. We constructed a kinetic-theory Knudsen-number ($\mathrm{Kn}$) map to analyze the contributions of the initial-state driver, which grows as $\mathrm{Kn}^{\kappa}$ with $\kappa \approx 2$, and a final-state viscous damping of the hydrodynamic response with characteristic scale $\mathrm{Kn}_0 \approx 0.27$ for the directed flow slope. This damping scale is found to be about a factor of 2.5 smaller than the $\mathrm{Kn}_0 \approx 0.7$ extracted from the elliptic flow. Furthermore, we determined the ratio of shear viscosity to entropy density, $\eta/s$, to be between 0.10 and 0.20, using an alternative method that does not rely on fitting flow harmonics.

We propose the one-point charge correlator (OPCC) in transversely polarized deep inelastic scattering as a new probe of the spin-dependent odderon. The OPCC is an infrared and collinear safe observable constructed solely from the charge and angular information of final-state charged particles. Because the charge weight is odd under charge conjugation, the contribution of the C-even pomeron to the OPCC vanishes identically in the small-$x$ eikonal limit, whereas the contribution of the C-odd spin-dependent odderon survives. We define a transverse single-spin asymmetry by normalizing the spin-dependent OPCC to the unpolarized charged-hadron one-point energy correlator. At small $x$, this asymmetry reduces to a ratio of spin-dependent odderon and pomeron contributions. We provide illustrative estimates of this asymmetry for Electron-Ion Collider kinematics within the small-$x$ dipole framework with Balitsky–Kovchegov evolution to guide experimental studies. Dedicated measurements of the OPCC asymmetry with a transversely polarized proton beam would provide new quantitative constraints on the currently unconstrained spin-dependent odderon.

Gaussian Process Regression is a powerful nonparametric Bayesian method that provides both predictions and principled uncertainty estimates in closed form. The majority of past applications have relied on agnostic priors, but physics knowledge can be systematically encoded into Gaussian Processes through physically-motivated mean functions and kernels. We exploit this capability in the context of nuclear physics, applying physics-guided Gaussian Process Regression to three problems: nucleon-nucleon scattering phase shifts, mass excesses, and the finite-temperature equation of state of dense matter. In each case, we demonstrate that encoding known theoretical structures yields substantial and systematic improvements in interpolation accuracy, uncertainty calibration, and extrapolation reliability over agnostic baselines. Our results highlight that the design of the prior, and in particular the mean function, is key for obtaining a reliable and well-calibrated Gaussian Process Regression.

We discuss a new family of publicly available collinear fragmentation functions (FFs) for pseudoscalar quarkonia, the NRFF1.0 set. It builds upon the Heavy-Flavor Non-Relativistic evolution (HF-NRevo) scheme, designed to describe heavy-hadron formation through leading-power fragmentation at moderate and large transverse momentum. Heavy-quarkonium production naturally involves both perturbative and non-perturbative QCD dynamics, from the production of the heavy $Q\bar{Q}$ pair to its formation into a physical bound state. Within NRFF1.0, Non-Relativistic Quantum Chromodynamics (NRQCD) provides the theoretical framework for calculating the FF inputs at the initial scale, which are subsequently evolved through the HF-NRevo scheme. This setup provides a precision baseline for investigating the underlying partonic hierarchy and jet structure across the moderate- to high-transverse-momentum regime. The explicit treatment of partonic channels and heavy-flavor thresholds makes this framework particularly suitable for exploring quarkonium-in-jet fragmentation, jet-quenching sensitivity, energy-loss mechanisms, and the emergence of medium-modified fragmentation patterns in the quark-gluon plasma.

The observation of a near-side enhancement in long-range correlations within high-multiplicity pA and pp collisions, commonly referred to as the ridge, has motivated significant efforts to quantify possible collective effects in small systems. Estimation of non-flow contributions in two-particle correlation measurements in small systems at the LHC typically relies on the assumption that jet-induced non-flow correlations are independent of event multiplicity. Consequently, this assumption allows the high-multiplicity non-flow to be estimated and accounted for by directly using low-multiplicity events. In this paper, the validity of this assumption is studied examining the multiplicity dependence of non-flow contributions estimated via two-particle correlation functions in pp collisions at RHIC energies $\sqrt{s} = 200$~GeV using the PYTHIA event generator. It is observed that selecting any specific multiplicity range inherently biases jet production dynamics. These biases introduce a non-trivial multiplicity dependence of the non-flow contribution at RHIC energies. The dependence of jet fragmentation and $p_{\text{T}}$-differential cross sections on event multiplicity is studied using a variety of commonly used multiplicity estimators, including mid-rapidity charged-particle multiplicity, forward multiplicity, and underlying-event activity. The results indicate that non-flow contributions do not exhibit simple multiplicity scaling and challenge the applicability of standard subtraction procedures utilized at LHC energies at lower RHIC collision energies.

The origin of fission-fragment spin remains unresolved. For $^{236}$U fission, we combine deformation-dependent finite-temperature pairing with a multidimensional scission-spectrum analysis. Near the pairing-quenching boundary, pair breaking exposes near-Fermi high-$\Omega$ intruder orbitals and opens high-$K$ channels. The resulting maximum spectroscopic capacities range from a few to more than a dozen units of $\hbar$. Rapid neck rupture acts as a non-adiabatic projection freeze-out, where pairing serves as a dynamical gate: its critical attenuation does not generate angular momentum but allows existing high-$K$ projections to be retained diabatically as local fragment-$K$ components while total angular momentum remains conserved.

In the present review, various facets of the phenomenological effective Gogny interaction, which was originally proposed in the 70's, are gathered for the first time in the same place. This involves both nuclear phenomena of interest that led to its creation and evolution as well as highly technical aspects that led the objectives to be achieved. With this in mind, a discussion structured around four key points is proposed. After a general introduction, the history and philosophy of the Gogny interaction is exposed. In particular, one highlights the way followed by D. Gogny to guide the determination of the parameters of its phenomenological interaction with results obtained from a realistic interaction using Hartree-Fock calculations and second order corrections and a G-matrix. One also shows how physical phenomena such as pairing or fission were essential to improve the initial parameterization. The evolution of the original analytical form over the years is then discussed. The second key point concern the emulator that was used for the generation of parameterizations. Its modifications, consistent with the evolution of its analytical form along the decades, are detailed. Other fitting procedures from other groups, more recent, are also evoked. The third key point is dedicated to the role of some nuclear matter properties in the fitting process and the acceptance of a parameterization. The objective of the last key point consists in highlighting some results obtained with the Gogny interaction in various domains such as nuclear structure, fission, reactions and nuclear data that have allowed to interpret many experimental data. Perpsectives are given explaining some paths that will be followed in the future concerning the functional itself as well as N-body approaches.