The present work aimed at the synthesis of the hitherto unknown ${}^{231}\mathrm{Am}$ and known ${}^{229}\mathrm{Am}$ isotopes via the $4n$ evaporation channels of the fusion reactions of ${}^{48}\mathrm{Ca}+{}^{187}\mathrm{Re}$ and ${}^{48}\mathrm{Ca}+{}^{185}\mathrm{Re}$, respectively. The new isotope ${}^{231}\mathrm{Am}$, with a half-life of ${47}_{-19}^{+85}\mathrm{s}$, was identified on the basis of five observed $\alpha$-decay chains. It emits $\alpha$ particles with an energy of 7.11(2) MeV. An upper limit of 0.66 was estimated for the electron-capture decay branch of ${}^{231}\mathrm{Am}$. No $\alpha$-decay chain from ${}^{229}\mathrm{Am}$ was observed, corresponding to a cross-section level of 0.03 nb for the detection of a single event. The $\alpha$-decay properties of ${}^{231}\mathrm{Am}$ are discussed in the framework of the Geiger-Nuttall empirical relation.

Based on the empirical coupled-channel model for calculating the capture cross section and the statistical model for calculating the survival probability, we apply the dinuclear system model for investigating the synthesis of superheavy element 116. The theoretical results can systematically reproduce the experimental data of the reactions ${}^{48}\mathrm{Ca}+{}^{248}\mathrm{Cm}$, ${}^{50}\mathrm{Ti}+{}^{242}\mathrm{Pu}$, ${}^{50}\mathrm{Ti}+{}^{244}\mathrm{Pu}$, and ${}^{54}\mathrm{Cr}+{}^{238}\mathrm{U}$. Simultaneously, the reactions ${}^{45}\mathrm{Sc}+{}^{243}\mathrm{Am}$, ${}^{51}\mathrm{V}+{}^{237}\mathrm{Np}$, ${}^{55}\mathrm{Mn}+{}^{231}\mathrm{Pa}$, and ${}^{58}\mathrm{Fe}+{}^{232}\mathrm{Th}$ are investigated. The results show that the calculated maximal evaporation-residue cross section is about 0.25 pb.

We propose an improved dinuclear system (DNS) model to describe both capture and noncapture transfer reactions within a unified framework. The main improvements in this work include the introduction of noncapture transfer processes and dynamic deformation mechanisms. The multinucleon transfer (MNT) reactions of ${}^{58,64}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ are used to test the improved model. The results show that the improved DNS model can successfully calculate the observables including mass distributions, total kinetic energy–mass distributions, and isotopic cross sections from both capture and noncapture transfer processes. These results indicate that the present DNS model is an effective tool for efficiently calculating product cross sections and investigating energy dissipation mechanisms in MNT reactions.

Background: The experiment of ${}^{180}\mathrm{Hg}$ fission revealed a possible “new asymmetric fission mode” in the preactinide region, posing challenges to current fission theory. Similarity in shell effects is observed between fission and quasifission, providing the possibility for widely exploring the topography of a fission potential-energy surface (PES).

Purpose: We aim to investigate the shell effects in the quasifission toward ${}^{180}\mathrm{Hg}$ and to explore their connection with the ${}^{180}\mathrm{Hg}$ fission.

Method: ${}^{68}\mathrm{Zn}+{}^{112}\mathrm{Sn}$, ${}^{74}\mathrm{Se}+{}^{106}\mathrm{Pd}$, ${}^{80}\mathrm{Kr}+{}^{100}\mathrm{Ru}$, and ${}^{84}\mathrm{Kr}+{}^{96}\mathrm{Ru}$ central collisions at different energies and projectile orientations are calculated using the Skyrme time-dependent Hartree-Fock approach. The static fission properties are calculated with the constrained Hartree-Fock-Bogoliubov method and compared with the quasifission results.

Results: Shell effects are found to hinder mass equilibration between the prefragments, enhancing the production of fragments near the $80/100$ mass split. By comparing the quasifission trajectories with the PES in the $(Q_{20},Q_{30})$ space, the role of the PES ridge in forming fragments is identified. The presence of the asymmetric valley causes the ${}^{68}\mathrm{Zn}+{}^{112}\mathrm{Sn}$ quasifission to exhibit a prefragment mass equilibration process and scission-point configuration similar to those of ${}^{180}\mathrm{Hg}$ fission. The elongated light fragment is found to be a key factor in reproducing the experimental fission total kinetic energies. Meanwhile, a more pronounced proton shell gap is found in the ${}^{68}\mathrm{Zn}+{}^{112}\mathrm{Sn}$ quasifission compared with other reactions.

Conclusions: By using quasifission dynamics as a probe of the fission pathway, the present calculations help clarify the specific influence of the PES topography and provide support for the dominance of proton shell effects and light fragment deformation in preactinide fission.

Parity-violating electron scattering provides a largely model-independent way of measuring neutron densities in nuclei that has important implications for the structure of nuclei and neutron stars. In this paper we calculate radiative corrections to the parity-violating asymmetry $A_{\mathrm{pv}}$ in electron-nucleus scattering including vertex and vacuum polarization contributions. We find large cancellations between the vertex corrections to the vector and axial-vector vertices. As a result, the total radiative correction in second Born approximation is dominated by vacuum polarization and is of order $-0.5\%$. Coulomb distortions have modest effects on radiative corrections for ${}^{12}\mathrm{C}$ and ${}^{48}\mathrm{Ca}$ nuclei. For ${}^{208}\mathrm{Pb}$, Coulomb distortions reduce the total radiative correction to only about 0.1%. Therefore, these corrections are not important for the interpretation of the PREX and MREX experiments on ${}^{208}\mathrm{Pb}$ and for the CREX experiment on ${}^{48}\mathrm{Ca}$. However, radiative corrections must be carefully included for a precision measurement of the weak charge of ${}^{12}\mathrm{C}$.

Three-nucleon force (3NF) plays an important role in understanding the structure of finite nuclei and the saturation properties of infinite nuclear matter. More specifically, 3NF should be necessary for each two-nucleon force (2NF) to obtain more accurate description of nuclear systems. 3NF derived from the chiral effective field theory has been successful in ab initio calculations of atomic nuclei. Most of established chiral nuclear forces have a nonlocal form in the momentum space. In this work, we construct a companion chiral 3NF specifically tailored to the new Idaho local position-space 2NF, and calculate binding energies and radii of nuclei up to ${}^{132}\mathrm{Sn}$. We find that a chiral 3NF with hybrid local and nonlocal regulators has advantages in improving the nuclear structure calculations of both binding energies and radii with the new Idaho 2NF. The two low-energy constants of 3NF are constrained by the ground-state energies of ${}^3\mathrm{H}$ and ${}^{16}\mathrm{O}$ as suggested in a recent work.

When training data are limited, data-driven models are especially vulnerable to optimization-related fluctuations from random initialization and to sampling-induced bias from insufficient training data. We address both challenges with transfer learning (TL): deep neural networks (DNNs) are first pretrained on $\alpha$-decay half-lives and then fine-tuned on a small cluster-decay dataset. The pretraining stage provides a physically informed initialization that stabilizes optimization, while transferred global-decay systematics regularize the fit and reduce sensitivity to training-set composition. Despite extreme data sparsity, the resulting models accurately predict cluster-decay half-lives for parent nuclei from ${}^{221}\mathrm{Fr}$ to ${}^{242}\mathrm{Cm}$. We further quantify how initialization and sample selection affect predictive accuracy and robustness, demonstrating that TL enables stable and reliable learning in the small-sample regime.

Combining the Lipkin-Nogami (LN) method with the deformed relativistic Hartree-Bogoliubov theory in continuum, the impact of the LN correction on the deformed halo nucleus ${}^{42}\mathrm{Mg}$ is investigated. With the LN correction, it is found that the halo structure of ${}^{42}\mathrm{Mg}$ persists, and the decoupling of its prolate core and oblate halo is significantly enhanced. This enhancement is analyzed in terms of the contributions of the single-neutron levels to the halo deformation.

We report the first results on ultracold neutron production from a new spallation-driven superfluid ${}^4\mathrm{He}$ (He-II) source at TRIUMF, which is being prepared for a new, precise measurement of the neutron electric dipole moment (nEDM). A total of $(9.3\pm 0.8)\times {10}^5$ ultracold neutrons (UCNs) were observed at a proton beam current of $37\mu \mathrm{A}$, when the target was irradiated for a period of $60\text{s}$. The results are in fair agreement with expectations based on a detailed simulation of neutron transport and ultracold neutron-source cryogenics. There is some indication that the new source might not be as limited by the conduction of heat through the He-II as originally expected. The results indicate that the source is likely to make its ultimate production goals, once the liquid deuterium cold moderator system is completed, with the expectation that $5.7\times {10}^7$ UCNs would be detected in the same experiment with full liquid levels. This would, for example, correspond to detection of $1.4\times {10}^6$ UCNs each Ramsey cycle, and a statistical uncertainty of $1\times {10}^{-27}e\mathrm{cm}$ on the neutron EDM in 280 days of running.

Although there exists a clear and, in principle, exact theoretical formulation for the equation of motion for the response of a correlated fermionic system, its numerical implementations for atomic nuclei require feasible approximations. One of the widely accepted approximations is a truncated harmonic oscillator (HO) basis, whose wave functions are used to expand the solutions obtained with realistic interactions. In this work, we extend previously employed HO basis truncated at $N_F=20$ fermionic shells to $N_F=50$ and perform a systematic study of the effects of such basis increase on nuclear resonances. The relativistic random-phase approximation (RRPA) and its extension by the particle-vibration coupling dubbed as relativistic time-blocking approximation are applied to the description of the monopole, dipole, quadrupole, and octupole resonances in ${}^{48}\mathrm{Ca}$, ${}^{78}\mathrm{Ni}$, and ${}^{132}\mathrm{Sn}$, and the RRPA studies are extended to ${}^{70}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$. A considerable sensitivity of the strength distributions to the HO basis size is found, especially for low-spin resonances in the light neutron-rich nuclei. The effects of the HO basis extension to $N_F=50$ are analyzed and linked to the involvement of proton and neutron continuum states and proton quasibound states in the strength formation. The obtained results point to the importance of the HO basis completeness and continuum effects in the nuclear response calculations and evaluation of the associated parameters of the nuclear equation of state. Statistical errors and systematic uncertainties in the RRPA strength functions are analyzed. They are found to be substantial for the monopole response but significantly smaller for the dipole, quadrupole, and octupole ones. Neither of them shows a pronounced mass dependence, and statistical errors are generally smaller than systematic uncertainties.

Two-dimensional Generator Coordinate Method calculations for the axial quadrupole ${\beta }_2$ and hexadecapole ${\beta }_4$ collective deformations are carried out with the Gogny force in a series of Xe, Ba, Ce, and Nd isotopes with neutron numbers covering both magic neutron shell closures N = 82 and N = 126. The underlying mean-field configurations are used to characterize the expected dynamic behavior of the system. Two regions of strong coupling between the quadrupole and hexadecapole degrees of freedom are found and characterized. Quantum fluctuations soften the mean-field ground state values of ${\beta }_2$ and ${\beta }_4$ in transitional regions. The ground state correlation energy coming from ${\beta }_4$ is comparable in size to the one coming from ${\beta }_2$, and both together amount to a sizable 1.5 MeV. Shape coexistence in some isotopes and its impact on the excitation energy of the first excited state are analyzed. Finally, the role of a second intruder orbital in the explanation of the large deformation parameters of some nuclei in the region is discussed.

The availability of low-energy antiproton beams at the CERN Antiproton Decelerator has renewed interest in using antimatter as a probe of nuclear structure and in forming exotic antiprotonic few-body systems. In this work, we extend the ab initio no-core shell model combined with the resonating group method (NCSM/RGM), which was successfully applied to light-nucleus structure and reactions, to antiproton-nucleus dynamics at low energies. The NCSM/RGM formalism is adapted to antiproton projectiles by removing the requirement of antisymmetrization under exchange of target and projectile constituents, while retaining a fully microscopic description of the nuclear target and the relative motion. We focus on the lightest systems, $\overline{p}+d$, $\overline{p}+{}^3\mathrm{H}$, and $\overline{p}+{}^3\mathrm{H}$, for which benchmarking against exact solutions of the Schrödinger equation enables stringent validation and helps disentangle methodological uncertainties—e.g., those associated with the choice of configurations included in the NCSM/RGM expansion—so that the dominant residual uncertainty can be attributed to the $N\overline{N}$ interaction. We compute phase shifts, scattering lengths, cross sections, antiprotonic-atom level shifts and widths, nuclear quasibound energies, and annihilation densities. We find that the hard short-range components of the meson-exchange-based $N\overline{N}$ interaction lead to slow convergence of the NCSM/RGM kernels expanded in a harmonic-oscillator basis, requiring exceptionally large model spaces and posing significant numerical challenges. We discuss practical strategies to mitigate these limitations and assess the impact of missing closed-channel configurations, which is a significant source of uncertainties in very light systems.

A density dependent nucleon-nucleon interaction (CDM3YR) has been parametrized based on the original M3Y-Reid interaction, to properly reproduce the saturation properties of symmetric nuclear matter (NM) in the nonrelativistic Hartree-Fock calculation with the energy of NM in a good agreement with the microscopic ab initio results over densities up to three times the saturation density. The real optical potential (OP) of symmetric ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$ systems is then calculated within the double-folding model (DFM) using the realistic densities of ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ nuclei and CDM3YR interaction, for the optical model analysis of elastic scattering at low energies and determination of the astrophysical $S$ factor of ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$ fusion in the barrier penetration model. The DFM calculation of the real OP for these two symmetric systems was also done using the original (density independent) M3Y-Reid interaction, and that added by a repulsive core suggested by Esbensen et al. [Phys. Rev. C 77, 054608 (2008); Phys. Rev. C 84, 064613 (2011)], to explore the impact of medium effects that are effectively encoded in the density dependence of the CDM3YR interaction.

We introduce a novel deep convolutional neural-network-(NN) enhanced Bayesian global analysis of bulk observables in highest-energy heavy-ion collisions using relativistic $2+1\mathrm{D}$ second-order viscous hydrodynamics with a dynamical freeze-out and with perturbative quantum chromodynamics (QCD) and saturation-based initial conditions from the event-by-event EKRT model. Our analysis has $13+2$ free parameters for the QCD-matter properties $+$ initial state, which are constrained by the experimental data from $\sqrt{s_{NN}}=200$ GeV $\mathrm{Au}+\mathrm{Au}$ collisions at Relativistic Heavy Ion Collider and 2.76 TeV $\mathrm{Pb}+\mathrm{Pb}$, 5.02 TeV $\mathrm{Pb}+\mathrm{Pb}$, and 5.44 TeV $\mathrm{Xe}+\mathrm{Xe}$ collisions at the Large Hadron Collider. We replace the computationally demanding hydrodynamical simulations by NNs, which predict bulk observables directly from the initial energy density profiles, event by event, and account for the QCD-matter properties. With the NN output, we train the Gaussian process emulators for obtaining centrality-class averaged observables and their uncertainties. The NNs reduce the computing time significantly, enabling us to include also statistics-hungry flow observables like $v_4$ and the normalized symmetric cumulant $\mathrm{NSC}(4,2)$ in the analysis. In this paper, we demonstrate the feasibility of the NN-based Bayesian global analysis. We find the data favoring a specific shear viscosity $\eta /s$ with a minimum-value plateau at temperatures $150\lesssim T\lesssim 230$ MeV, with $0.12\lesssim {(\eta /s)}_{\min }\lesssim 0.18$. The bulk viscous coefficient $\zeta /s$ is nonzero at $200\lesssim T\lesssim 300$ MeV. The Knudsen number at the freeze-out is $0.8–2.3$, while the ratio of the mean free path to the system size at freeze-out is in the range $0.3–1.2$, implying that the freeze-out indeed happens at the expected limit of the applicability of hydrodynamics.

Neutron-skin thicknesses provide a sensitive probe of the isovector sector of the nuclear equation of state and its density dependence, commonly characterized by the symmetry-energy slope parameter $L$. A wide variety of experimental and observational methods have been used to extract neutron skins, ranging from hadronic and electromagnetic probes of finite nuclei to inferences from neutron-star observations. Each approach carries distinct theoretical and systematic uncertainties, complicating global interpretations and obscuring genuine physical trends. In this work we present a hierarchical Bayesian framework for the statistically consistent synthesis of heterogeneous neutron-skin constraints. The neutron-skin thickness is modeled as a smooth latent function of isospin asymmetry and nuclear size, while method-dependent bias parameters and intrinsic nuisance widths are introduced to account for unmodeled experimental and theoretical systematics. Focusing on the tin isotopes, we infer probabilistic neutron-skin trends from ${}^{100}\mathrm{Sn}$ to ${}^{140}\mathrm{Sn}$, finding minimal uncertainties near stability and increasing uncertainties toward the proton-rich and neutron-rich extremes. We assess the consistency of nuclear energy-density functionals and obtain conditional constraints on the symmetry-energy parameters. The resulting posterior exhibits a pronounced compression of the symmetry-energy slope parameter $L$, reflecting the dominant sensitivity of neutron skins to subsaturation symmetry pressure. We demonstrate that our hierarchical Bayesian framework provides robust and transparent constraints on the subsaturation isovector sector of the nuclear equation of state.

This work extends previous results on the inverse scattering problem within the framework of Marchenko theory (fixed-$l$ inversion). In particular, I approximate an $n$-channel $S$ matrix as a function of the first-channel momentum $q$ by a sum of a rational term and a truncated sinc series for each matrix element. Relativistic kinematics are taken into account through the correct momentum-energy relation, and the necessary minor generalization of Marchenko theory is given. For energies where only a subset of scattering channels is open, the analytic structure of the $S$ matrix is analyzed. I demonstrate that the submatrix corresponding to closed channels, particularly near their thresholds, can be reconstructed from the experimentally accessible submatrix of open channels. The convergence of the proposed method is verified by applying it to data generated from a direct solution of the scattering problem for a known potential and comparing the reconstructed potential with the original one. Finally, the method is applied to the analysis of $S_{31} \pi N$ scattering data.

Background: The low-lying level structures of deformed odd-odd nuclei away from the region of stability have been sparsely characterized due to low cross-section yields in reactions, short half-lives, and lack of dedicated studies. One such interesting case is the odd-odd rare-earth light-mass isotope ${}^{162}\mathrm{Lu}$, where, except for the ground state (gs) $J^{\pi }=1^{-}\{\pi 1/2^{+}[411\downarrow ]\otimes \nu 3/2^{-}[521\uparrow ]\}$, assignments of other low-lying levels are unknown or ambiguous. The nucleus is reported to have two low-lying isomeric states with uncertain assignments of spin-parity, level energy, and orbital configuration without specific information on the individual $\beta$-decay branchings.

Purpose: This work uses the well-tested empirical two-quasiparticle rotor model (TQRM) with explicit inclusion of the residual neutron-proton interaction to deduce the low-energy spectrum of ${}^{162}\mathrm{Lu}$ and thereby characterize the isomeric states. Following the characterization of ${}^{162}\mathrm{Lu}$, a similar trend of isomers in neighboring odd-odd ${}^{164,166,168}\mathrm{Lu}$ isotopes is analyzed.

Methods: The empirical three-step TQRM calculations estimate the spin-parities, orbital configurations, and energies of the physically admissible two-quasiparticle (2qp) states in the odd-odd system. Experimental energies of the single-particle (1qp), proton ($p$), and neutron ($n$) states close to the Fermi surface in the mass region of interest are taken as inputs. The spin-parities of the low-lying 2qp bandheads are determined by coupling of the 1qp $p$ and $n$ orbitals while the level energies are calculated using the TQRM energy expressions. $\beta$-decay selection rules are employed for mapping the favored $\beta$-branching of the gs and isomers to select daughter levels.

Results: The 1.5 min isomer in ${}^{162}\mathrm{Lu}$ is deduced to have $J^{\pi }=4^{-}\{\pi 5/2^{+}[402\uparrow ]\otimes \nu 3/2^{-}[521\uparrow ]\}$, with estimated level energy $E_x \approx 62$ keV. The 1.9 min isomer is characterized for the first time with $J^{\pi }=6^{+}\{\pi 9/2^{-}[514\uparrow ]\otimes \nu 3/2^{-}[521\uparrow ]\}$ and energy $E_x \approx 160$ keV. Based on these assignments, individual $\beta$-decay branches of the gs and the two isomers to the daughter levels in ${}^{162}\mathrm{Yb}$ are proposed. The study is extended to neighboring isotopes ${}^{164,166,168}\mathrm{Lu}$. A candidate for the isomer, tentatively proposed in an earlier study of ${}^{164}\mathrm{Lu}$, is identified as $J^{\pi }=4^{-}\{\pi 5/2^{+}[402\uparrow ]\otimes \nu 3/2^{-}[521\uparrow ]\}$ with $E_x \approx 52$ keV. The excitation energy of the $J^{\pi }=3^{+}$ isomer in ${}^{168}\mathrm{Lu}$, currently listed with a large uncertainty, is deduced as $E_x \approx 100$ keV, significantly improving its value.

Conclusions: The low-lying levels of ${}^{162}\mathrm{Lu}$ were constructed using the empirical TQRM calculations. The spin-parities, orbital configurations, and level energies of the two low-lying isomers were estimated, and their $\beta$ decay pathways were proposed for the first time. Isomers in the neighboring odd-odd isotopes were also studied. These proposed assignments can be used as location guides for in-depth experimental studies.

Background: The synthesis of new elements, extending the periodic table, remains one of the central challenges in modern science and requires the production of superheavy nuclei in nuclear reactions. However, the production of superheavy nuclei involves highly complex reaction mechanisms, and theoretical predictions remain subject to substantial uncertainties in nuclear-physics inputs and models.

Purpose: Fusion reactions with ${}^{48}\mathrm{Ca}$ beams, which have been used for synthesis of $Z\le 118$ nuclei, face practical limitations for the synthesis of nuclei with $Z\ge 119$ because of the short half-lives and limited availability of suitable target nuclei. We estimate evaporation-residue cross sections ${\sigma }_{\mathrm{ER}}$ for the reactions ${}^{48}\mathrm{Ca}+{}^{254}\mathrm{Es}, {}^{50}\mathrm{Ti}+{}^{249}\mathrm{Bk}, {}^{51}\mathrm{V}+{}^{248}\mathrm{Cm}$, and ${}^{54}\mathrm{Cr}+{}^{243}\mathrm{Am}$, and examine the role of nuclear-mass-model uncertainties.

Methods: We employ a hybrid framework for the three stages of the fusion reaction. The capture stage is described by the coupled-channels method, the competition between fusion and quasifission by a multidimensional Langevin approach, and the de-excitation stage by a statistical model. ${\sigma }_{\mathrm{ER}}$ is evaluated by combining the corresponding capture, compound-nucleus formation, and survival probabilities.

Results: Using the nuclear properties from the FRDM2012 mass model, the maximum values of ${\sigma }_{\mathrm{ER}}$ summed over all $xn$ channels are calculated to be 233, 206, 33, and $38\mathrm{fb}$ for the ${}^{48}\mathrm{Ca}+{}^{254}\mathrm{Es}, {}^{50}\mathrm{Ti}+{}^{249}\mathrm{Bk}, {}^{51}\mathrm{V}+{}^{248}\mathrm{Cm}$, and ${}^{54}\mathrm{Cr}+{}^{243}\mathrm{Am}$ reactions, respectively. The relative relationship between the reaction $Q$ value and the Coulomb-barrier height is found to be a key factor in comparing reactions leading to the same atomic number. In particular, the relatively small $Q$ value magnitude of the ${}^{51}\mathrm{V}+{}^{248}\mathrm{Cm}$ reaction leads to a higher excitation energy and a reduced survival probability, giving the smallest ${\sigma }_{\mathrm{ER}}$ among the reactions considered. We also find a significant mass-model dependence on the survival probability. Using the nuclear properties predicted by several mass tables (FRDM2012, FRDM1995, WS4, and KTUY05) yields differences in the survival probability ranging from about one to several orders of magnitude. This difference mainly originates from the neutron binding energy and shell-correction energy predicted by the nuclear mass models.

Conclusions: The cross sections ${\sigma }_{\mathrm{ER}}$ for the synthesis of $Z=119$ nuclei are governed by both the relative relationship between the reaction $Q$ value and the Coulomb-barrier height and nuclear-mass-model uncertainties that strongly affect the survival probability. Both effects must be taken into account in theoretical predictions and in the planning of future experiments.

Pion photoproduction in the $\vec{\gamma }\vec{p}\to {\pi }^{0}p$ reaction has been measured in the FROzen Spin Target (FROST) experiment at the Thomas Jefferson National Accelerator Facility. In this experiment, circularly polarized photons with energies up to 3.082 GeV impinged on a transversely polarized frozen-spin target. Final-state protons were detected in the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer. The polarization observables $T$ and $F$ have been extracted for $W$ from 1445 to 2525 MeV, of which the energy range is much broader, and the precision is better than the existing measurements in higher $W$ ranges. The data generally agree with predictions of present partial-wave analyses but also show marked differences for higher $W$ ranges. By incorporating the present data into the databases, the Scattering Analysis Interactive Data (SAID) fits have been improved with relatively small ${\chi }^2$ and significant changes in the parameters of the $\mathrm{\Delta }\left(1910\right)1/2^{+}$ and $N\left(2190\right)7/2^{-}$ have been found with the JüBo model.

Jet modification in heavy-ion collisions provides microscopic access to the properties of the quark-gluon plasma. However, conventional approaches based on traditional global observables, such as $R_{AA}$, capture limited information about the complex dynamics of parton-medium interactions during hard scatterings. In this work, we apply sequential machine-learning architectures to the jet declustering history tree, achieving improved classification performance compared with static models that learn only from a single stage of the jet evolution. We find that models trained on different medium implementations exhibit meaningful performance modification under cross-domain validation, indicating that machine learning is sensitive to implementation-specific features that traditional observables may not resolve. These results suggest new opportunities for using machine learning as an analysis tool to overcome some of the limitations of traditional jet-modification studies.