Background: Calculating microscopic optical potentials for elastic scattering at intermediate energies from light nuclei in an ab initio fashion within the Watson expansion has been established within the last few years.

Purpose: Based on the Watson expansion of the multiple scattering series, we employ a nonlocal translationally invariant nuclear density derived within the symmetry-adapted no-core shell model (SA-NCSM) framework from a chiral next-to-next-to-leading order (NNLO) nucleon-nucleon interaction and the very same interaction for a consistent full-folding calculation of the effective (optical) potential for nucleon-nucleus scattering for medium-heavy nuclei.

Methods: The leading order effective (optical) folding potential is computed by integrating over a translationally invariant SA-NCSM one-body scalar density, spin-projected momentum distribution, and the Wolfenstein amplitudes $A, C$, and $M$. The resulting nonlocal potentials serve as input for a momentum space Lippmann-Schwinger equation. In the SA-NCSM, the model space is systematically up-selected using $\mathrm{Sp}(3,\mathbb{R})$ symmetry considerations.

Results: For the light nucleus of ${}^6\mathrm{He}$, we establish a systematic selection scheme in the SA-NCSM for scattering observables. Then, we apply this scheme to calculations of scattering observables, such as differential cross sections, analyzing powers, and spin rotation functions for elastic proton scattering from ${}^{20}\mathrm{Ne}$ and ${}^{40}\mathrm{Ca}$ in the energy regime between 65 and 200 MeV, and compare to available data.

Conclusions: Our calculations show that the leading order effective nucleon-nucleus potential in the Watson expansion of multiple scattering theory obtained from an up-selected SA-NCSM model space describes ${}^{40}\mathrm{Ca}$ elastic scattering observables reasonably well to about 60 degrees in the center-of-mass frame, which coincides roughly with the validity of the NNLO chiral interaction used to calculate both the nucleon-nucleon amplitudes and the one-body scalar and spin nuclear densities.

Nuclear coherent population transfer (NCPT) plays an important role in the exploration and application of atomic nuclei. How to achieve high-fidelity NCPT remains so far challenging. Here, we investigate the complete population transfer of nuclear states. We first consider a cyclic three-level system, based on the mixed-state inverse engineering scheme by adding additional laser fields in an open three-level nuclear system with spontaneous emission. We find the amplitude of the additional field is related to the ratio of the pump and Stokes field amplitudes. As long as an appropriate additional field is selected, complete transfer can be achieved even when the intensities of the pump and Stokes fields are exceedingly low. The transfer efficiency exhibits excellent robustness with respect to laser peak intensity and pulse delay. We demonstrate the effectiveness through examples such as ${}^{229}\mathrm{Th}, {}^{223}\mathrm{Ra}, {}^{113}\mathrm{Cd}$, and ${}^{97}\mathrm{Tc}$, which have a long lifetime excited state, as well as ${}^{187}\mathrm{Re}, {}^{172}\mathrm{Yb}, {}^{168}\mathrm{Er}$, and ${}^{154}\mathrm{Gd}$ with a short lifetime excited state. Focusing on the case without additional coupling, we further reduce the three-level system to an effective two-level problem. We modify the pump and Stokes pulses by using counterdiabatic driving to implement high-fidelity population transfer. The schemes open up new possibilities for controlling nuclear states.

Spontaneous fission of ${}^{252}\mathrm{Cf}$ and fusion-induced fission of ${}^{250}\mathrm{Cf}$ are investigated within a multidimensional Langevin model. The potential-energy surface is calculated in the macroscopic-microscopic Lublin-Strasbourg drop (LSD) $+$ Yukawa-folded approach using the four-dimensional (4D) Fourier-over-spheroid shape parametrization. The dynamical evolution described by the Langevin equation is coupled to neutron evaporation, thereby allowing for the possibility of multichance fission. Charge equilibration and excitation-energy sharing between the fragments emerging at scission are evaluated, and their deexcitation is finally computed. The correlation between various observables, particularly the isotopic properties of the fragments, is discussed and compared with the experiment whenever available. The theoretical predictions are generally in good agreement with the data.

It has been traditionally hypothesized that the heavy quark (charm $c$ and bottom $b$) fragmentation is universal across different collision systems, based on the notion that hadronization as a soft process should occur at the characteristic nonperturbative quantum chromodynamics (QCD) scale, ${\mathrm{\Lambda }}_{QCD}$. However, this universality hypothesis has recently been challenged by the observation that the $c$- and $b$-baryon production relative to their meson counterparts in minimum bias proton-proton ($pp$) collisions at the CERN Large Hadron Collider (LHC) energies is significantly enhanced as compared to the electron-positron ($e^{+}{e}^{-}$) collisions. The conception of nonuniversality is unambiguously reinforced by the latest measurement of the charged-particle multiplicity dependence of the $b$-baryon–to–meson yield ratio, ${\mathrm{\Lambda }}_b/B$, by the LHCb experiment in $\sqrt{s}=13\mathrm{TeV}pp$ collisions at the LHC, evolving continuously from the saturation value in minimum bias $pp$ collisions toward the small value in $e^{+}{e}^{-}$ collisions as the system size gradually reduces. We address the multiplicity dependence of $b$-baryon production in the canonical statistical hadronization model with input $b$-hadron spectrum augmented with many hitherto unobserved states from quark model predictions. We demonstrate that the decreasing trend of the ${\mathrm{\Lambda }}_b/B$ toward low multiplicities can be quantitatively understood from the canonical suppression on the yield of ${\mathrm{\Lambda }}_b$, as caused by the requirement of strict conservation of baryon number in sufficiently small systems. We have therefore proposed a plausible scenario for understanding the origin of the nonuniversality of heavy quark fragmentation in elementary collisions.

The significant increase in the ($L/K$) ratio of ${}^7\mathrm{Be}$ implanted in tantalum, compared to that in mercury telluride, has been quantitatively explained by using ab initio density functional calculations. The result highlights the effect of lattice compression on the ($L/K$) ratio of ${}^7\mathrm{Be}$. Predictions for the ($L/K$) ratio in several untested cases have also been provided. Density functional calculations were employed to understand the notable $\left(\approx 6\mathrm{eV}\right)$ downward shift observed in the $K$ capture to the nuclear ground state ($K$-GS) peak in the recoil energy spectrum of ${}^7\mathrm{Li}$ following the electron capture decay of ${}^7\mathrm{Be}$ implanted in a small tantalum lattice and the resulting reduced energy difference between the $K$-GS and $L$-GS peaks. No such anomaly was observed when ${}^7\mathrm{Be}$ was implanted in mercury telluride. The calculations predict that the chemical shifts of the ${}^7\mathrm{Li} 1s$ state for the implantation of ${}^7\mathrm{Li}$ in different media are $\approx \left(0-2\right)$ eV. We hypothesize that the observed large downward shift of the $K$-GS peak in the ${}^7\mathrm{Li}$ recoil spectrum might be attributed to the difference of Fermi energies of tantalum and mercury telluride.

Background: The nucleosynthesis of several proton-rich nuclei is determined by radiative proton-capture reactions on unstable nuclei in nova explosions. One such reaction is ${}^{23}\mathrm{Mg}(p,\gamma ){}^{24}\mathrm{Al}$, which links the NeNa and MgAl cycles in oxygen-neon novae.

Purpose: The purpose of our study is to extract ${}^{23}\mathrm{Mg}(p,\gamma )$ resonance strengths from proton-unbound states in ${}^{24}\mathrm{Al}$, produced via the ${}^{24}\mathrm{Mg}({}^3\mathrm{He},t)$ reaction.

Methods: A beam of ${}^3\mathrm{He}^{2+}$ ions at 50.7 MeV is used to produce the states of interest in ${}^{24}\mathrm{Al}$. Proton-triton angular correlations are measured with a $K=600$ QDD magnetic spectrometer and a silicon detector array, located at iThemba LABS, South Africa.

Results: We measure the excitation energies of the four lowest proton-unbound states in ${}^{24}\mathrm{Al}$ and place lower limits on ${\mathrm{\Gamma }}_p/\mathrm{\Gamma }$ values for these four states. Together with shell-model calculations of partial $\gamma$ widths, the experimental data are also used to determine resonance strengths for the four lowest ${}^{23}\mathrm{Mg}(p,\gamma ){}^{24}\mathrm{Al}$ resonances.

Conclusions: The energy of the dominant first ${}^{23}\mathrm{Mg}(p,\gamma )$ resonance is determined to be $E_r=478\pm 4$ keV, with a resonance strength of $\omega \gamma =19\pm 9$ meV.

Background: In the theoretical analysis of nuclear fission observables, dissipation strength is often adjusted locally to reproduce the experimental data. The global trend of the dissipation strength over the whole mass range of fissioning nuclei is still not known convincingly. Also, its connection with fission timescales is essential to understand the reaction dynamics.

Purpose: We extracted the nuclear dissipation strength by reproducing the experimental prescission neutron multiplicities for reactions forming compound nuclei in the mass range of $168\le A\le 256$. Subsequently, we predicted the systematics of fission lifetime over this range of compound nuclear mass.

Method: We employed a one-dimensional Langevin dynamical model for fission, where shape-dependent shell correction and one-body dissipation are used. The dissipation strengths for different compound systems are extracted by reproducing the measured prescission neutron multiplicities. Obtained strengths are shown to consistently reproduce the average total kinetic energy of the fission fragments. Subsequently, dynamical fission-time distributions were simulated in coincidence with these neutron multiplicities.

Results: We identified three different mass regions depending on the required dissipation strength: (i) for compound nuclear mass number $A<210$, the role of dissipation is minimal, (ii) in $210⪅A⪅244$, shell correction is found to influence the dissipation strength strongly, and (iii) for $A⪆244$ the dynamics is strongly driven by dissipation. Further, for lighter masses with a fission barrier height between $18\text{and}30$ MeV, fission time appeared to depend very weakly on the fission barrier, whereas, for heavy nuclei, fission time is shown to be well correlated with the barrier height of the primary compound nucleus.

Conclusion: Our paper provides a global understanding of the nuclear dissipation strength and the fission lifetime based on the experimental neutron multiplicities. These systematics will be helpful in estimating fission time in heavy ion-induced reactions.

Femtoscopy studies of pion radiation in heavy-ion collisions have been conducted extensively at all available collider energies, both theoretically and experimentally. In all these studies special attention is given to $m_T$ dependency of pion femtoscopy radii, usually approximated by a power-law function at transverse momenta above $200\mathrm{MeV}/c$. However, the radii behavior has been much less explored for the ultrasoft pions, possessing transverse momentum comparable to or lower than the pion mass. For many experimental setups this region is difficult to measure. In this work we present theoretical calculations of pion emission in the ultrasoft region in the two hybrid models iHKM and $\text{LHYQUID}+\mathrm{th}\text{ERMINATOR2}$. Along with the particle transverse momentum spectra, we present the calculated femtoscopy radii, in both one-dimensional and three-dimensional representations. We investigate the radii dependence on pair $m_T$ and observe, in particular, a departure from the power-law behavior at ultrasoft momenta, potentially reflecting a decoupling of such slow pions from the rest of collectively expanding system. We provide the theoretical interpretation of this result and discuss its significance, in particular, for the ongoing nonidentical particle femtoscopy analysis for pairs consisting of a pion and a baryon (or of a pion and a charmed meson).

We study the impact of nuclear structure uncertainties on a measurement of the weak charge of ${}^{12}\mathrm{C}$ at the future Mainz Energy Recovering Superconducting Accelerator (MESA) facility in Mainz. Information from a large variety of nuclear models, accurately calibrated to the ground-state properties of selected nuclei, suggest that a 0.3% precision measurement of the parity-violating asymmetry at forward angles will not be compromised by nuclear structure effects, thereby allowing a world-leading determination of the weak charge of ${}^{12}\mathrm{C}$. Furthermore, we show that a combination of measurements of the parity-violating asymmetry at forward and backward angles for the same electron-beam energy can be used to extract information on the nuclear weak charge distribution. We conclude that a 0.34% precision on the weak radius of ${}^{12}\mathrm{C}$ may be achieved by performing a 3% precision measurement of the parity-violating asymmetry at backward angles.

Charge-exchange reactions are versatile probes for nuclear structure. In particular, when populating isobaric analog states, these reactions are used to study isovector nuclear densities and neutron skins. The quality of the information extracted from charge-exchange data depends on the accuracy of the reaction models and their inputs; this work addresses these two points. First, we quantify the uncertainties due to effective nucleon-nucleus interactions by propagating the parameter posterior distributions of the recent global optical model KDUQ [C. D. Pruitt, J. E. Escher, and R. Rahman, Phys. Rev. C 107, 014602 (2023)] to $(p,n)$ reaction observables populating the isobaric analog state, at beam energies in the range of 25–160 MeV. Our analysis, focusing on ${}^{48}\mathrm{Ca}$, shows that the total parametric uncertainties on the cross sections are around 60–100%. The source of this uncertainty is mainly the transition operator as the uncertainties from the distorted waves alone are less than about 15%. Second, we perform a comparison between two- and three-body models that both describe the dynamics of the reaction within the DWBA. The predictions from these two models are similar and generally agree with the available data, suggesting that one-step DWBA is sufficient to describe the reaction process. Only at a beam energy of 25 MeV are there possible signs that a one-step assumption is not fully correct. This work provides motivation for the quantification of uncertainties associated with the transition operator in three-body model. It also suggests that further constraint of the optical potential parameters is needed for increased model precision.

Internal surface standing wave resonances can occur when either electromagnetic or acoustic waves interact with cylindrical or spherical material structures. These resonances are often termed whispering gallery resonances, a reference to the focusing of sound within a cylindrical gallery. Here, a report is presented of an investigation to establish the importance of such surface standing wave resonances for nuclear wave scattering from unstable or weakly bound nuclei. To facilitate the investigation an analytical model, the transitional rotational model, has been developed to probe the occurrence of whispering gallery phenomena within nuclear wave scattering. Understanding such phenomena can be relevant when nuclear structure information are derived from scattering experiments. Moreover, it can also be important for the understanding of nuclear pathways leading to stellar explosions.

Background: Emission of bremsstrahlung photons in the scattering of protons off deuterons is investigated on the microscopic cluster basis in a wide region of beam energy from low energies up to 1.5 GeV.

Purpose: Our aim is to construct a model extracting new information about the structure of the deuteron from analysis of accompanying bremsstrahlung in proton-deuteron scattering.

Methods: A three-cluster model of bremsstrahlung is constructed. The formalism includes the form factor of the deuteron, which characterizes the dependence of bremsstrahlung cross sections on the structure of the deuteron. This gives a possibility to investigate the structure of nuclei from analysis of bremsstrahlung cross sections.

Results: We studied the dependence of the bremsstrahlung cross section on the structure of the deuteron. We used three different shapes of the deuteron wave functions. Besides, we also calculated the cross section by neglecting the internal structure of the deuteron. Analysis of the dependence of the cross section on such a parameter shows the following. (1) At beam energies 145 and 195 MeV used in experiments, the bremsstrahlung cross section is not sensitive enough to variations in the shape of the deuteron wave functions. (2) A stable difference between cross sections calculated with and without the internal structure of the deuteron is observed at higher bean energy (higher than 500 MeV). (3) The spectrum is increased as we pass from the structureless deuteron (the oscillator length $b=0$) to the deuteron described by the shell-model wave function (the realistic oscillator length) inside the full energy region of the emitted photons.

Conclusions: Our cluster model is a suitable tool to study the structure of the deuteron with high enough precision from bremsstrahlung analysis. We propose new experiments for such an investigation.

The interacting shell model, a configuration-interaction method, is a venerable approach for low-lying nuclear structure calculations, but it is hampered by the exponential growth of its basis dimension as one increases the single-particle space and/or the number of active particles. Recent, quantum-information-inspired work has demonstrated that the proton and neutron sectors of a nuclear wave function are weakly entangled. Furthermore, the entanglement is smaller for nuclides away from $N=Z$, such as heavy, neutron-rich nuclides. Here we implement a weak entanglement approximation to bipartite configuration-interaction wave functions, approximating low-lying levels by coupling a relatively small number of many-proton and many-neutron states. This truncation scheme, which we present in the context of past approaches, reduces the basis dimension by many orders of magnitude while preserving essential features of nuclear spectra.

A collective model Hamiltonian incorporating a $\beta \text{−}\mathrm{soft}$ potential is proposed to elucidate phenomena related to triaxiality in transitional systems. The solutions derived from the model built within the core-particle scheme can be approximated using Bessel functions and subsequently applied to describe the exotic high-spin phenomena observed in the $A\approx 130$ mass region. The results indicate that chiral and wobbling rotations in a $\beta \text{−}\mathrm{soft}$ system may exhibit robustness against $\beta$ vibrations, suggesting a collective vibration mechanism for multiple chiral doublet bands and multiple rotation-wobbling bands in triaxial nuclei.

A microscopic finite-temperature model based on time-dependent nuclear density functional theory (TDDFT) is employed to study the induced-fission process of ${}^{226}\mathrm{Th}$. The saddle-to-scission dynamics of this process is explored, starting from various points on the deformation surface of Helmholtz free energy at a temperature that corresponds to the experimental excitation energy, and following self-consistent isentropic fission trajectories as they evolve toward scission. Dissipation effects and the formation of excited fragments are investigated and, in particular, the difference in the evolution of the local temperature along asymmetric and symmetric fission trajectories is studied. The relative entropies and entanglement between fission fragments emerging at scission are analyzed.

Excited states in the neutron-deficient nuclide ${}^{155}\mathrm{Hf}$ have been investigated in experiments performed at the Accelerator Laboratory of the University of Jyväskylä. The ${}^{155}\mathrm{Hf}$ nuclei were produced in fusion-evaporation reactions induced by beams of 295 and 315 MeV ${}^{58}\mathrm{Ni}$ ions bombarding an isotopically enriched ${}^{102}\mathrm{Pd}$ target and separated using the recoil mass separator MARA. An isomeric state having a half-life of 510(30) ns was discovered and is interpreted as a seniority $\upsilon =3, (\pi h_{11/2}^2\otimes \nu f_{7/2})27/2^{-}$ configuration. The $\gamma$-ray transitions emitted in the deexcitation of the isomeric state to the ground state were identified and a level scheme was constructed, from which the excitation energy of the isomer was determined to be 2581.5(10) keV. A $B\left(E2\right)$ value of 0.45(3) W.u. was deduced for the 105.4 keV transition depopulating the isomeric state. The deduced level scheme and $B\left(E2\right)$ value are compared with systematics and shell-model calculations.

The first systematic experimental study of the neutron-rich Br isotopes with two complementary state-of-the-art techniques is presented. These isotopes were populated in the fission process at two different facilities, GANIL and ILL. New spectroscopic information was obtained for odd-even ${}^{87–93}\mathrm{Br}$ isotopes and the experimental results were compared with state-of-the-art large scale shell model (LSSM) and discrete nonorthogonal (DNO) shell model calculations. As a result of such theoretical approaches, a transition from prolate (${}^{87,89}\mathrm{Br}$) to oblate (${}^{91,93}\mathrm{Br}$) shapes is obtained from the subtle balance between proton and neutron quadrupole deformations, as a clear signature of a pseudo-SU3 quadrupole regime.

Mass distributions of fission fragments arising from the slow quasifission (SQF) process, derived by comparing the measured data with theory for several reactions, show distinct features. Irrespective of fissioning systems, the peak corresponding to lighter fragments in the SQF mass distribution is found to be always at $A\approx 96$, whereas the peak position of the heavier fragments increases linearly with the mass of the dinuclear system. Further, the yield of quasifission events decreases with the increasing projectile energy. These observations within certain model dependence provide clear evidences of shell effect in slow quasifission, where the lighter fragments are possibly some closed-shell nuclei in the mass region $A\approx 96$ (possibly ${}^{96}\mathrm{Zr}$ or ${}^{94}\mathrm{Sr}$). Further, the results from a model independent approach involving multi-Gaussian fit to the high energy data points reaffirm the above conclusion.

Background: Significant theoretical uncertainties exist with respect to the initial condition of the hydrodynamic description of ultrarelativistic heavy-ion collisions. Several approaches exist, of which some contain initial momentum information. Its impact is commonly assumed to be small and final flow is seen as a linear response to the initial-state eccentricity.

Purpose:The purpose of this work is to study the effect of exchanging initial condition models in a modular hybrid approach, especially regarding changes in the event-by-event correlations of elliptic and triangular flow with initial-state quantities like eccentricity and initial-state transverse momentum.

Method:This study is performed in the hybrid approach SMASH-vHLLE, composed of the hadronic transport approach SMASH and the $(3+1)\mathrm{d}$ viscous hydrodynamic code vHLLE. The initial condition models investigated are SMASH IC, ${\mathrm{T}}_{\mathrm{R}}\mathrm{ENTo}$, and IP-Glasma. Correlations are calculated on an event-by-event basis between the eccentricities and momentum anisotropies of the initial state as well as the momentum anisotropies in the final state, both for central and off-central collisions for AuAu collisions at $\sqrt{s_{NN}}=200$ GeV. The response of the final-state to initial-state properties is studied.

Results:This work demonstrates that, although averaged values for the initial eccentricities of these models are very similar, substantial differences exist both in the distributions of eccentricities, the correlations among the initial-state properties as well as in the correlations between initial-state and final-state properties. Notably, whereas initial-state momentum anisotropy is shown to not affect the final-state flow, the presence of radial flow affects the emergence of final-state momentum anisotropies.

Conclusions:Inclusion of radial flow in the linear fit improves the prediction of final-state flow from initial-state properties. The presence of transverse momentum in the initial state has an effect on the emergence of flow and is therefore a relevant part of initial-state models, challenging the common understanding of final-state momentum anisotropies being a linear response to initial-state eccentricity only.