The very neutron-deficient ${}^{115}\mathrm{I}$ nucleus has been studied using the ${}^{58}\mathrm{Ni}({}^{64}\mathrm{Zn},$ $1\alpha 3\mathrm{p})$ reaction and JUROGAM 3 $\gamma$-ray detector array coupled to the MARA recoil-mass separator. The previously known bands have been largely revised and have been extended to high spin by five newly identified rotational bands. Many other levels and transitions have been identified both at low and high spin. A set of nine rotational bands with well-established spins and parities are analyzed. One important result is the observation of the terminating state in one of the bands. Five bands start at low spin and are assigned to the single-particle proton orbitals $d_{5/2}$, $g_{7/2}$, $g_{9/2}$, and $h_{11/2}$, which are close to the $Z=53$ Fermi surface for deformations around ${\varepsilon }_2=0.2–0.3$. Particle number conserving cranked shell-model calculations have been performed to investigate the evolution of the observed bands at high spin, and have been compared to the cranked Nilsson-Strutinsky calculations, revealing differences in the predicted configurations and nature of the observed crossings in some of the bands.

Proton radioactivity provides a sensitive probe of single-particle structure beyond the proton drip line, but global half-life descriptions are often limited by the approximate treatment of nuclear-structure effects. We find that introducing an $E_{\mathrm{mic}}$-dependent proton preformation factor within the transfer-matrix method (TMM) markedly improves the agreement with experiment and substantially reduces the sensitivity to the adopted proton-daughter potential. We perform a systematic TMM study of 45 established proton emitters from I to Bi using three representative interaction potentials, namely the Woods-Saxon (WS), cosh-type (Cosh), and Guo2013 proximity (Prox) forms. Starting from baseline calculations with $S_p=1$, we extract proton preformation factors nucleus by nucleus and, for each fixed-$l$ group, establish a linear correlation between ${log}_{10}{S}_p$ and the microscopic mass correction $E_{\mathrm{mic}}$, with uncertainties of the fitted coefficients estimated by Monte Carlo resampling. After including the resulting preformation factors, the root-mean-square (RMS) deviations in ${log}_{10}{T}_{1/2}$ are reduced from 1.088, 1.059, and 0.944 to 0.353, 0.352, and 0.343 for the WS, Cosh, and Prox potentials, respectively, while the three calculations converge to a common modified Geiger-Nuttall trend. We further predict proton preformation factors and partial half-lives for six candidate proton emitters with energetically allowed or experimentally indicated proton emission, providing quantitative benchmarks for future measurements and microscopic studies of proton radioactivity.

Neutron knockout reactions on beams of ${}^{104,102}\mathrm{Cd}$ and ${}^{104}\mathrm{Sn}$ are presented. States in the residual ${}^{103,101}\mathrm{Cd}$ and ${}^{103}\mathrm{Sn}$ nuclei are populated, including low-lying $7/2^{+}$ states of $\nu g_{7/2}$ character. These states have half-lives $\approx 400$ ps due to their low energy and hindered $B(M1;7/2^{+}\to 5/2^{+})$ strengths. The excited-state half-lives were measured using their Doppler-shifted line shapes, and the resulting $B\left(M1\right)$ strengths are compared to valence space in medium similarity renormalization group (VS-IMSRG) calculations. The VS-IMSRG calculations underpredict the $l$-forbidden $M1$ strengths in the ${}^{100}\mathrm{Sn}$ region, as well as in other regions of the nuclear chart near ${}^{40}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$.

We present coupled-channel Gamow shell model (GSM-CC) calculations of the ${}^{13}\mathrm{O}$($p,p$) and ${}^{14}\mathrm{O}$($p,p$) elastic-scattering reactions in the $\mathrm{core}+\mathrm{valence}$ nucleon picture. Within this unified framework, we investigate the structural and scattering properties of the proton-unbound nuclei ${}^{14}\mathrm{F}$ and ${}^{15}\mathrm{F}$. GSM-CC reproduces the ground-state separation energies and describes the low-lying spectra and decay widths of ${}^{14}\mathrm{F}$ ($2_1^{-}, 1^{-}, 3^{-}, 2_2^{-}, 4^{-}$) and ${}^{15}\mathrm{F}$ ($1/2^{+}, 5/2^{+}$) nuclear states. For ${}^{15}\mathrm{F}$, phase shifts and spectroscopic factors in the $1/2^{+}$ and $5/2^{+}$ channels are analyzed to identify the dominant configurations. The calculated ${}^{14}\mathrm{O}$($p,p$) excitation functions at several ${\theta }_{\mathrm{c}.\mathrm{m}.}$ angles agree with available experimental data, thereby providing a benchmark for the reaction framework. We then provide GSM-CC calculations and predictions related to the ${}^{13}\mathrm{O}$($p,p$) elastic scattering reaction and characterize the five lowest resonances in ${}^{14}\mathrm{F}$ in terms of their energies, widths, and spectroscopic factors. Notably, and consistently with other theoretical studies, GSM-CC predicts an excited $2_2^{-}$ resonance contributing to the ${}^{13}\mathrm{O}$($p,p$) excitation function at higher energy, which was not identified in the previous experimental measurement. Comparison with the GSM structure calculations reflects the enhanced coupling provided by the configuration mixing present in the GSM-CC framework.

High-spin states in ${}^{60}\mathrm{Cu}$ are investigated on the basis of reaction-channel-selected $\gamma$-ray spectroscopy. Data stem from three experiments that used the same fusion-evaporation reaction at similar beam energies. The Gammasphere $\gamma$-ray spectrometer was combined with the Microball CsI(Tl) detector array and sets of liquid-scintillator neutron detectors which allowed us to identify and tag on evaporated light charged particles and neutrons, respectively. A level scheme is proposed which comprises more than 300 $\gamma$-ray transitions connecting more than 100 excited states. Predictions from cranked Nilsson-Strutinsky calculations describe the observed high-spin collective structures in ${}^{60}\mathrm{Cu}$. Predictions of shell-model calculations are probed with a suite of low- to medium-spin states of both parities. Taking into account isospin-symmetry-breaking terms in these calculations, a case study of the yrast line of the weakly bound mirror nucleus ${}^{60}\mathrm{Ga}$ is presented.

(Multi-)strange particle production rates and transverse momentum distributions are measured at midrapidity $\left(\right|y|<0.5)$ as a function of the charged-particle multiplicity density by the ALICE experiment at the CERN Large Hadron Collider (LHC), using proton-proton collisions at a center-of-mass energy of $\sqrt{s}=5.02$ TeV. This study extends similar studies performed at $\sqrt{s}=7$ TeV and $\sqrt{s}=13$ TeV to a lower-energy regime, improving the statistical precision and extending the measurement to previously unexplored low-multiplicity regions. While ${\mathrm{K}}_{\mathrm{S}}^0$, $\mathrm{\Lambda }$, and $\mathrm{\Xi }$ yields can be described with a linear multiplicity dependence within uncertainties, the $\mathrm{\Omega }$ yields follow a significantly faster than linear increasing trend. For all analyzed particles, the overall production rate is consistent with that observed at higher energy and at similar multiplicity densities. Transverse momentum distributions are observed to evolve with multiplicity. Several state-of-the-art QCD-inspired Monte Carlo models have been compared with the data, testing some recently introduced features to address the findings at higher energies. Models can qualitatively describe the transverse momentum spectra and the $\mathrm{\Lambda }/{\mathrm{K}}_{\mathrm{S}}^0$ spectral ratio only if collectivity is introduced in the evolution of the system.

We systematically investigate the scaling properties of the transverse momentum spectra for pions, kaons, and protons in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=7.7$, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV, as well as in $\mathrm{U}+\mathrm{U}$ collisions at $\sqrt{s_{NN}}=193\mathrm{GeV}$, across different centrality classes, using experimental data from the collaborations at the Relativistic Heavy Ion Collider (RHIC). Universal scaling emerges when the particle transverse momentum spectra are scaled by global physical quantities, i.e., the average total particle multiplicity and mean transverse momentum, confirming recent scaling findings from the data at the Large Hadron Collider (LHC) by the ExTrEMe Collaboration. The scaling behavior breaks down in the high $p_{\mathrm{T}}$ region and in peripheral collisions. We provide a natural explanation for these observations in the framework of a blast-wave-type model built upon the Cooper-Frye formula. Furthermore, we demonstrate the equivalence between the scaling found by the ExTrEMe Collaboration and the Hwa-Yang scaling, which was proposed two decades ago.

We develop the theoretical framework for semi-inclusive deep-inelastic scattering on a polarized spin-1 target and apply it to scattering on the polarized deuteron with spectator nucleon tagging. In Part I (this article) we present the general form of the semi-inclusive cross section and polarization observables for the spin-1 target. A relativistically covariant formulation in terms of four-vectors and invariant polarization parameters is employed. The target polarization is described by a spin density matrix with vector and tensor polarization. The spin and azimuthal angle dependence of the semi-inclusive cross section is derived and parametrized in terms of invariant structure functions. To validate the result, the structure functions are expressed as photon-target helicity amplitudes with known symmetry properties. The expressions presented here are kinematic (no assumptions about particle production dynamics) and valid in all regions of the deep-inelastic final state (current and target fragmentation regions). In Part II (following article), we consider deep-inelastic scattering on the polarized deuteron with spectator nucleon tagging as a special case of target fragmentation. The semi-inclusive structure functions are computed by separating nuclear and hadronic structure, and the polarization observables are explored as functions of the tagged nucleon momentum.

We develop the theoretical framework for semi-inclusive deep-inelastic scattering on a polarized spin-1 target and apply it to scattering on the polarized deuteron with spectator nucleon tagging. In Part I (previous article), we present the general form of the semi-inclusive cross section and polarization observables for the spin-1 target. In Part II (this article), we consider deep-inelastic scattering on the polarized deuteron with spectator nucleon tagging as a special case of target fragmentation. Methods of light-front quantization are employed to separate nuclear and hadronic structure in the high-energy process and achieve a composite description. The light-front wave function of the polarized deuteron is obtained from a rotationally covariant three-dimensional wave function in the center-of-mass frame of the proton-neutron system. The tagged structure functions are computed in the impulse approximation. The momentum and spin distribution of the active nucleon are controlled by the deuteron polarization and the detected spectator momentum ($D/S$ wave ratio). The cross section and spin asymmetries are evaluated for general deuteron polarization (vector and tensor, longitudinal and transverse) as functions of the spectator momentum. Tensor-polarized spin asymmetries of order unity are achieved for spectator momenta of approximately 300 MeV, which select configurations with a large $D$ wave. Sum rules for the tagged spin structure functions are derived. The results can be used for simulations of spectator tagging in future polarized fixed-target experiments (Jefferson Lab) or at the Electron-Ion Collider.

An effective operator is exactly equivalent to the long-wavelength form of the $M1$ operator in transition matrix elements. It allows us to analytically and numerically analyze the $M1$ contribution to the ${}^4\mathrm{He}{(d,\gamma )}^6\mathrm{Li}$ reaction. Isoscalar $M1$ transitions from an initial $S$ wave are shown to be forbidden in radiative capture reactions when distortion is neglected in the initial state. An illustrative calculation in a three-body model with proton, neutron, and a structureless $\alpha$ interacting through effective forces leads to a negligible $M1 S$ factor at small energies. The dominant $M1$ contribution comes from transitions from an initial $S$ wave to isospin 1 components of the ${}^6\mathrm{Li}$ ground state. The importance of the orthogonality between initial and final states is emphasized. It is suggested that using this effective $M1$ operator in other models should clarify the origin of large discrepancies between $M1 S$ factors appearing in the literature.

We revisit the neutron-deuteron scattering using the wave-packet continuum discretization (WPCD) method with the Epelbaum-Krebs-Meißner (EKM) chiral nuclear force at various chiral orders. We rederive the permutation operator and solve the Faddeev-AGS equations directly, without rewriting the initial Faddeev kernel $t{G}_0$ or introducing pseudostates, thereby rendering the approach easily extendable to a relativistic framework. This is the first application of the EKM interaction within the WPCD approach. We find that, up to the next-to-next-to-next-to-leading order (${\mathrm{N}}^3\mathrm{LO}$), the differential cross sections are well described, while the long-standing $A_y$ puzzle remains unresolved, consistent with previous studies. The overall agreement provides a useful benchmark for the present framework and supports its application to future, more comprehensive calculations.

The symmetric double-$\alpha$ decay of ${}^{216,218}\mathrm{Rn}$ and ${}^{220,222}\mathrm{Ra}$ has been investigated at the ISOLDE facility. Radioactive molecular ${}^{220,222}\mathrm{RaF}$ ion beams were produced and delivered at an energy of 30 keV with intensities of approximately ${10}^3$ and ${10}^5\mathrm{pps}$, respectively. The ions were implanted into a thin self-supported carbon foil surrounded by four double-sided silicon strip detectors. Three ${}^{14}\mathrm{C}$ cluster emission events from ${}^{222}\mathrm{Ra}$ were observed. The measured branching ratio, $B=[10.1_{-6.4}^{+7.8}\left(\mathrm{stat}\right)\pm 1.1\left(\mathrm{syst}\right)]\times {10}^{-10}$, is consistent with the adopted value. For the simultaneous symmetric double-$\alpha$ decay ($E_{{\alpha }_1}=E_{{\alpha }_2}$ and ${\theta }_{{\alpha }_1{\alpha }_2}={180}^{\circ }$), no excess events were observed in the region of interest. Consequently, experimental upper limits on the branching ratios were derived at the level of ${10}^{-7}$ and ${10}^{-9}$ for the ${}^{220}\mathrm{Ra}$ and ${}^{222}\mathrm{Ra}$ decay chains, respectively.

The ${}^3\mathrm{He}$ puzzle, namely, that ${}^3\mathrm{He}$ exhibits anomalously higher kinetic energies per nucleon than tritons ($t$) and $\alpha$ particles in the multifragmentation processes, remains a prominent open issue in the field of heavy-ion collision, as existing interpretations rely primarily on the measured energy spectra and lack constraints from multiple experimental observables. In this work, focusing on the ${}^3\mathrm{He}$ puzzle in comparison to $t$, the differences between $t$ and ${}^3\mathrm{He}$ in in-plane/out-of-plane emission dynamics and emission chronology from the necklike region in the midcentral ${}^{40}\mathrm{Ca}+{}^{40}\mathrm{Ca}$ collisions at 35 MeV/u are experimentally investigated using the two-particle correlation functions. It is found that, compared to $t, {}^3\mathrm{He}$ shows stronger in-plane collective motion, weaker out-of-plane collective motion, and delayed emission time, collectively indicating that, compared to $t, {}^3\mathrm{He}$ tends to be emitted in a less violent collision process or the ${}^3\mathrm{He}$ production is suppressed in a more violent process from an inverse perspective. This work offers novel insights into the ${}^3\mathrm{He}$ puzzle by combining dynamical and chronological observables.

We investigate microscopically systematic behavior of shape coexistence in even-even ${}^{106–120}\mathrm{Sn}$ isotopes in the framework of the shell model. The two-particle and two-hole (2p-2h) proton excitations across the $Z=50$ closed shell gap are essential to describe the deformed intruder states built on the first excited $0_2^{+}$ state, which intrudes into the spherical normal states, indicating the shape coexistence. In addition, the neutron excitations to the $1h_{11/2}$ orbit are important for a parabolic behavior of the intruder band with a minimum in the excitation energy near the neutron midshell $N=66$ point. The calculations predict that the crossing between the intruder and normal bands occurs between spin $I=4$ and $I=6$. From the potential energy surface (PES) with particle-number and angular-momentum projections, collective wave function, and quadrupole moments, it is shown that the calculations describe shape coexistence structure for the midshell Sn nuclei.

Sub-barrier photo-induced fission in ${}^{236}\mathrm{U}(\gamma ,f)$ is investigated within the nonequilibrium Green's function method. A model space for the fission process is constructed by superposing Skyrme-Hartree-Fock wave functions along the fission path allowing the particle-hole excitation. Then, the transition from the photoabsorption channel to the fission channel is described by the nonequilibrium Green's function formalism. The calculated fission cross section in the incident gamma-ray energy range $5\mathrm{MeV}\le E_{\gamma }\le 6\mathrm{MeV}$ reproduces the overall behavior of the experimental data, including the suppression below the fission barrier. An eigenchannel analysis of the wave propagation in the present fission model space is also performed, and the first eigenchannel is found to dominate the fission probability. This result supports the Bohr-Wheeler transition-state picture from a microscopic viewpoint.

The deformation properties within the ${}^{98–106}\mathrm{Ru}$ even-even isotopic chain, are investigated by means of the covariant density functional theory with a density-dependent point-coupling x parametrization. The considered nuclei are found to exhibit very shallow prolate and triaxial ground-state deformation. This information is used to ascertain their dynamical behavior within prolate $\gamma$-stable and $\gamma$-unstable instances of a phenomenological Bohr-Mottelson Hamiltonian with an octic potential in the axial deformation variable. The comparative study of the low-lying collective states, revealed the presence of a shape phase transition from low to high deformation, as well as evidence of shape coexistence and mixing between spherical vibrator, $\gamma$-unstable or prolate configurations in ground and excited states. It is also shown that the effect of shape coexistence and mixing on the $\gamma$-band states can account to some extent for the typical $\gamma$-unstable staggering even in prolate $\gamma$-stable conditions.

Based on the octupole core-quasiparticle coupling model, the effect of different octupole-correlated configurations—$\pi (2p_{3/2},1g_{9/2}), \pi (2d_{5/2},1h_{11/2})$, and $\pi (2f_{7/2},1i_{13/2})$—on wobbling motion in octupole deformed odd-$A$ nuclei is systematically investigated. Spin coherent state plots are constructed to visualize the angular momentum geometry. The results demonstrate that wobbling motion can occur in both positive- and negative-parity bands built on these octupole-correlated orbitals. As the spin increases, a transition from transverse wobbling to longitudinal wobbling is revealed, with the critical spin increasing with the particle angular momentum. This shows the crucial role of high-$j$ particles in stabilizing the transverse wobbling mode.

The Ichimura-Austern-Vincent (IAV) sum-rule formalism for inclusive breakup reactions $a+A\to b+\mathrm{anything}$ treats the detected fragment $b$ as a spectator by replacing its interaction with the target by an optical potential. This assumption becomes questionable when $b$ is a loosely bound composite particle such as a deuteron. I derive a generalization that removes the spectator approximation and retains $b\text{"s}$ internal degrees of freedom, providing state-resolved inclusive cross sections. Within the distorted-wave Born approximation, all nonspectator effects enter through the source function via the operator $V_{bA}-U_{bA}$. The exact sum rule involves the full $x+A$ resolvent ${(E_{x,0}^{+}-H_{xA})}^{-1}$, while a single-channel IAV-like expression is recovered only when the explicit target dependence of $V_{bA}$ is neglected; post-prior equivalence is preserved in both cases, since $V_{bA}$ cancels in the difference between the post- and prior-form residual interactions, and is verified explicitly in the single-channel limit. A key conceptual finding is that the standard IAV result for structureless $b$ corresponds, under closure and a reduction of $b\text{"s}$ internal space, to the total inclusive cross section summed over all of $b\text{"s}$ internal states, rather than the cross section for $b$ in a specific state. An operator-level estimate for $b=d$ on ${}^{208}\mathrm{Pb}$ shows that the nonspectator correction is not a small perturbation at the nuclear surface. The present work is purely formal: it establishes the theoretical framework and identifies the relevant operators, while quantitative assessment of the cross-section impact awaits a full numerical evaluation of the source integrals.

A systematic Bayesian analysis of experimentally measured nuclear level densities for ${}^{204,206,207,208}\mathrm{Bi}$ and ${}^{209}\mathrm{Po}$ nuclei has been performed to investigate the damping of shell effects with increasing excitation energy. The analysis indicates high shell-damping rates (${\gamma }_0$ = $0.{59}_{-0.10}^{+0.22}, 0.{53}_{-0.06}^{+0.16}$, and $0.{49}_{-0.07}^{+0.20} {\mathrm{MeV}}^{-1}$) in neutron-deficient bismuth nuclei (${}^{204}\mathrm{Bi},{}^{206}\mathrm{Bi}$, and ${}^{207}\mathrm{Bi}$), implying a rapid attenuation of shell effects as the excitation energy increases. Systematic investigation incorporating different treatments of pairing correlations and spin cutoff prescriptions demonstrate that the deduced shell-damping rates have minimal model dependence. These findings provide valuable insight into the excitation energy dependence of shell structure near the closed-shell nuclei.

The proton evaporation spectrum has been measured in an exclusive experiment for ${}^{60}\mathrm{Co}$, which is populated in the ${}^{57}\mathrm{Fe}$(${}^7\mathrm{Li},\alpha$) reaction and decays into ${}^{59}\mathrm{Fe}+\mathrm{p}$. A statistical-model analysis of the coincident proton spectra enabled the extraction of the excitation-energy-dependent nuclear level density (NLD) of ${}^{59}\mathrm{Fe}$. The extracted NLD shows good consistency with available microscopic predictions and the RIPL-3 evaluated data, thereby providing an important experimental benchmark for this short-lived nucleus. It was further used to estimate the Maxwellian-averaged neutron-capture cross section relevant for astrophysical reaction rates, particularly for the ${}^{58}\mathrm{Fe}$ nucleus.