Investigation of isospin symmetry breaking in the mirror nuclei, particularly those near the drip line with states significantly influenced by the Thomas-Ehrman shift (TES) effect, is a prominent topic in nuclear structure. Previous studies have demonstrated that ${}^{16}\mathrm{Ne}/{}^{16}\mathrm{C}$ exhibit dynamic TES. In this work, we utilize the Gamow shell model (GSM) to explore the dynamic TES in ${}^{16}\mathrm{Ne}/{}^{16}\mathrm{C}$ and ${}^{18}\mathrm{Mg}/{}^{18}\mathrm{C}$. The calculated excitation energies of the low-lying states of these two mirror partners align well with available experimental data. The many-body configuration and average occupations are also calculated to investigate isospin symmetry further breaking in these mirror states. Our results indicate significant differences in the many-body configurations and average occupations of the ground states of ${}^{16}\mathrm{Ne}/{}^{16}\mathrm{C}$, suggesting a dynamic TES in ${}^{16}\mathrm{Ne}/{}^{16}\mathrm{C}$. A similar pattern is observed in the ${}^{18}\mathrm{Mg}/{}^{18}\mathrm{C}$ mirror partners, indicating that their low-lying states also exhibit the dynamic TES properties. Furthermore, the contributions of different components of the GSM Hamiltonian for the mirror states are calculated to provide additional evidence of the dynamic TES properties in the low-lying states of ${}^{16}\mathrm{Ne}/{}^{16}\mathrm{C}$ and ${}^{18}\mathrm{Mg}/{}^{18}\mathrm{C}$.

Nuclear many-body systems, ranging from nuclei to neutron stars, are some of the most interesting physical phenomena in our universe, and quantum Monte Carlo (QMC) approaches are among the most accurate many-body methods currently available to study them. In recent decades, interactions derived from chiral effective field theory (EFT) have been widely adopted in the study of nuclear many-body systems. One drawback of the QMC approach is the requirement that the nuclear interactions need to be local, whereas chiral EFT interactions usually contain nonlocalities. In this work, we leverage the capability of computing second-order perturbative corrections to the ground-state energy in order to develop a self-consistent approach to including nonlocal operators in QMC calculations. We investigate both the deuteron and the neutron-matter equation of state in order to show the robustness of our technique and pave the way for future QMC calculations at higher orders in the EFT, where nonlocal operators cannot be avoided.

The short-time approximation is a method introduced to evaluate electroweak nuclear response for systems with $A\ge 12$, extending the reach of first-principle many-body quantum Monte Carlo calculations. Using realistic two- and three-body nuclear interactions and consistent one- and two-body electromagnetic currents, we calculate longitudinal and transverse response densities and response functions of ${}^{12}\mathrm{C}$. We compare the resulting cross sections with experimental data for electron-nucleus scattering, finding good agreement.

The ${}^{229}\mathrm{Th}$ nucleus has a unique transition at only 8 eV which could be used for a novel nuclear clock. We investigate theoretically the prospects of driving this electric dipole-forbidden transition with vortex light beams carrying orbital angular momentum. Numerical results are presented for two experimental configurations which are promising for the design of the planned nuclear clock: a trapped ion setup and a large ensemble of nuclei doped into ${\mathrm{CaF}}_2$ crystals which are transparent in the frequency range of the nuclear transition. We discuss the feasibility of the vortex beam nuclear excitation and compare the excitation features with the case of plane wave beams. Differences between the two scenarios and the specific advantages of vortex beams are limited by challenging experimental requirements for pitch angle and field intensity.

α-induced total reaction cross sections in the low-energy region below 400 MeV are investigated using an intranuclear cascade model based on the extended framework for nucleon- and deuteron-induced reactions. Experimental data for ${}^{12}\mathrm{C}$, ${}^{28}\mathrm{Si}$, ${}^{40}\mathrm{Ca}$, and ${}^{208}\mathrm{Pb}$ targets are reproduced well by calculations performed with reasonable parameters close to those determined in other studies. It is shown that two effects, namely discrete level constraint (DLC) and the Coulomb effect, provide important contributions that depend on the incident energy and target. The DLC effect is limited to a narrow region of low energy and is very important in light targets. The Coulomb effect is decisive on cross sections in ${}^{208}\mathrm{Pb}$, while the DLC contribution for the heavy target is small. It is concluded that these effects determine the curve of incident-energy dependence of the total reaction cross sections, and this trend in the contribution of both effects is consistent with proton- and deuteron-induced total reaction cross sections.

In the present work, we investigate the excitation rates and population dynamics of ${}^{229}\mathrm{Th}$ nuclei induced by inelastic electron scattering, focusing on how electron energy, flux, and ionic charge state influence the excitation process of the nuclei. Using the Dirac Hartree-Fock-Slater method, we calculate cross sections for both the isomeric state (8.36 eV) and the second-excited state (29.19 keV) of ${}^{229}\mathrm{Th}$ over a wide range of ionic charge states and electron energies. Our results demonstrate that these factors significantly impact the nuclear excitation efficiency. The effect of indirect excitation through the second-excited state on enhancing the accumulation of nuclei in the isomeric state cannot be ignored. By applying rate equations to model the temporal evolution of nuclear populations, we show that under optimal conditions up to 10% of ${}^{229}\mathrm{Th}^{4+}$ ions can be accumulated in the isomeric state. These findings provide important insights for optimizing electron-nucleus interactions, contributing to the development of ${}^{229}\mathrm{Th}$-based nuclear clocks and relevant precision measurement applications.

Neutron deficient nuclei from ${}^{74}\mathrm{Se}–{}^{196}\mathrm{Hg}$ are thought to be produced by $\gamma$-induced reactions $(\gamma ,n), (\gamma ,p)$, and $(\gamma ,\alpha )$ processes. The stacked foil activation method was used to measure the ${}^{113}\mathrm{In}(\alpha ,\gamma )$ reaction cross section at $E_{\mathrm{lab}}=8.29–17.78\mathrm{MeV}$. ${}^{113}\mathrm{In}(\alpha ,n)$ reaction cross section was also measured at $E_{\mathrm{lab}}=9.80–17.78\mathrm{MeV}$. ${}^{113}\mathrm{In}(\alpha ,\gamma )$ reaction cross section was measured for the first time at $E_{\mathrm{lab}}=8.29\pm 0.76\mathrm{MeV}$ ($\sigma =1.5\pm 0.3\mu \mathrm{b}$). Vacuum evaporation technique was used for preparing the targets ($60–85\mu \mathrm{g}/{\mathrm{cm}}^2$). Theoretical statistical model calculations were performed with different nuclear input parameters and compared with the experimental results. An appropriate $\alpha$-optical potential has been identified from the ($\alpha ,\gamma$) and $(\alpha ,n)$ fitting, which provides the major source of uncertainty in the statistical model calculations. The other nuclear input parameters, such as level density and $\gamma$-ray strength function, were also constrained for theoretical calculations. ${}^{113}\mathrm{In}(\alpha ,\gamma ){}^{117}\mathrm{Sb}$ and ${}^{117}\mathrm{Sb}(\gamma ,\alpha ){}^{113}\mathrm{In}$ reaction rates were calculated using best-fit input parameters.

Electric quadrupole ($E2$) moments and transitions provide measures of nuclear deformation and related collective structure. However, matrix elements of the $E2$ operator are sensitive to the nuclear wave function at large distances and are poorly convergent within the ab initio no-core shell model approach. We perform for the first time a systematic study of the ratio of neutron to proton quadrupole transition matrix elements, $M_n/M_p$, with the no-core shell model. We find this observable is well-converged and provides a new and robust tool for comparing with experimental results. Our parameter-free results for $M_n/M_p$ for the carbon isotopes and ${}^{10}\mathrm{Be}$ compare well with experiment, where available, and provide additional support for the emerging picture that ab initio results align well with collective enhancements in light nuclei.

Background: The ${}^{176}\mathrm{Yb}(n,\gamma ){}^{177}\mathrm{Yb}\to {}^{177}\mathrm{Lu}$ reaction is of interest in nuclear medicine as it is the preferred production route for ${}^{177}\mathrm{Lu}$. This radioisotope has seen a very fast growth of usage in nuclear medicine in recent years due to its outstanding properties. New data on this reaction could provide useful information for production at new facilities.

Purpose: We aim to resolve resonances in the ${}^{176}\mathrm{Yb}(n,\gamma ){}^{177}\mathrm{Yb}$ reaction for the first time. Previous capture measurement provided data at thermal point and encompassed integral measurements in the range from 3 keV to 1 MeV, where three time-of-flight measurements are available, but with low resolution to resolve the resonances. Transmission measurements from the 1970s resolved and analyzed some resonances.

Method: We measure the neutron capture cross section of ${}^{176}\mathrm{Yb}(n,\gamma ){}^{177}\mathrm{Yb}$ by means of the time-of-flight technique at the Experimental Area 1 of the n_TOF facility at CERN using an enriched $\underset{2}{{}^{176}\mathrm{Yb}}{\mathrm{O}}_3$ sample and an array of four ${\mathrm{C}}_6{\mathrm{D}}_6$ liquid scintillation detectors.

Results: We have resolved 164 resonances up to 21 keV, including 96 new ones. We also provide new capture experimental data from 90 eV to 3 keV, and we extend the resolved resonance region up to 21 keV. In addition, resonance decay widths, ${\mathrm{\Gamma }}_{\gamma }$ and ${\mathrm{\Gamma }}_n$, are provided for all resonances together with resonance energies.

Conclusions: The ${}^{176}\mathrm{Yb}(n,\gamma ){}^{177}\mathrm{Yb}$ reaction has been measured, providing resonance parameters for the first time from a few eV to 21 keV. The analysis of the resonances has been carried out and compared with previous works and existing libraries, revealing discrepancies due to the new information on ${\mathrm{\Gamma }}_{\gamma }$ parameters. Our results are consistent with the ${\mathrm{\Gamma }}_n$ parameters obtained in transmission measurements.

This work aims to differentiate strangeness produced from hard processes (jetlike) and softer processes (underlying event) by measuring the angular correlation between a high-momentum trigger hadron ($h$) acting as a jet proxy and a produced strange hadron [$\varphi \left(1020\right)$ meson]. Measuring $h\text{−}\varphi$ correlations at midrapidity in $p$-Pb collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ as a function of event multiplicity provides insight into the microscopic origin of strangeness enhancement in small collision systems. The jetlike and the underlying-event-like strangeness production are investigated as a function of event multiplicity. They are also compared between a lower and higher momentum region. The evolutions of the per-trigger yields within the near-side (aligned with the trigger hadron) and away-side (in the opposite direction of the trigger hadron) jets are studied separately, allowing for the characterization of two distinct jetlike production regimes. Furthermore, the $h\text{−}\varphi$ correlations within the underlying event give access to a production regime dominated by soft production processes, which can be compared directly to the in-jet production. Comparisons between $h\text{−}\varphi$ and dihadron correlations show that the observed strangeness enhancement is largely driven by the underlying event, where the $\varphi /h$ ratio is significantly larger than within the jet regions. As multiplicity increases, the fraction of the total $\varphi \left(1020\right)$ yield coming from jets decreases compared to the underlying event production, leading to high-multiplicity events being dominated by the increased strangeness production from the underlying event.

We consider isospin-asymmetric matter in the parity-doublet model within an extended mean-field calculation, increasing continuously the neutron excess all the way to pure neutron matter. We compute the liquid-gas and the chiral phase transitions occurring at zero to moderate temperatures but put special emphasis on the phase structure of matter at zero temperature and large baryon densities. The calculation of the free energy involves the solution of gap equations. This is achieved by transforming these gap equations into ordinary differential equations that control the flow with increasing baryon density of various physical quantities: the isoscalar condensate, the densities of protons and neutrons, as well as those of their respective chiral partners. In this formulation, the initial conditions for the differential equations determine the entire phase structure. It is further demonstrated that the threshold for the onset of the population of the chiral partners is exclusively determined by the fermionic parameters, most notably by the chiral-invariant mass of the nucleon. We underline the role of a parity symmetry energy in driving the equilibration of the nucleons and their parity partners across the chiral transition. We provide a detailed analysis of the changes in the matter properties as one varies the neutron excess, including a special discussion of the chiral limit, and we compare systematically the parity-doublet model to its corresponding singlet model, where the chiral partner of the nucleon is neglected. Finally, we focus on neutron matter and compute the equation of state and the speed of sound. The results are confronted with those of other calculations as well as to recent Bayesian analyses of neutron-star observations.

We employ the multipole expansion within the unified electroweak theory to develop a complete calculation method of the electron scattering cross section for light nuclei. The specific calculations for ${}^{6,7}\mathrm{Li}$ and ${}^7\mathrm{Be}$ nuclei indicate that the conventional impulse approximation can be applied to the electron-nucleus scattering only when the incident electron energy does not exceed twice the nucleon mass. In addition, the quasielastic scattering cross section of ${}^7\mathrm{Li}$ in the excitation from its ground state to the nearest excited state and that of elastic scattering in the ground state are independently treated, whereas they have not been separately measured in experiments. The obtained scattering cross sections corresponding to an appropriate adjustment of the harmonic oscillator parameter along with the V-A structure interpret reasonably well the available experimental data at MeV energies and provide predictive information at GeV energies. This gives new perspectives in studying the structure of nuclei and the weak interactions via electron or lepton scattering at high (GeV) energies, considering nuclei rather than quarks.

Within an isospin- and momentum-dependent Boltzmann-Uehling-Uhlenbeck transport model, we investigate the yield ratios of neutron-proton $\left[R\right(n/p\left)\right]$ in the peripheral collisions of neutron-deficient ${}^{48,50,52,54,56,58}\mathrm{Ni}+{}^{58}\mathrm{Ni}$ systems at beam energy of 400 MeV/nucleon. The short-range correlation (SRC) induced by the tensor force in the isosinglet neutron-proton interaction channel is incorporated into the extended Thomas-Fermi approximation (ETF*) for the nucleon kinetic-energy density in finite nuclei. This leads to a neutron skin in momentum ($k$) space for neutron-deficient nucleus. It is shown that the $R(n/p)$ from different neutron-deficient Ni projectiles follows a negative exponential trend with their proton skin thickness. However, when considering the neutron skin in $k$ space, the attenuation intensity of the yield ratio with the thickness of the proton skin decreases. Therefore, it is necessary to account for the effects of SRC and the neutron skin in $k$ space when deducing an isotope's proton skin thickness from other known neutron-deficient isotopes. Furthermore, we find that the surface properties of a nucleus as a projectile can be perfectly reflected by its $N/Z$ dependence of the $R(n/p)$ in the gas phase at projectile-like midrapidity. Hence, it is a helpful observable to study the surface properties of neutron-deficient nuclei near the $\beta$-stability line.

A new type of photoinduced nuclear reactions is considered when a photon is absorbed by a continuum state and accompanied by nuclear rearrangement. An important example of such reactions is $d+t+\gamma \to \alpha +n$ which, in the regions of space containing a hot $d-t$ mixture and a very large number of low-energy photons, can dominate the $d+t\to \alpha +n$ fusion reaction, leading to an additional high-energy release. The present estimates of the environmental conditions where this might happen are made based on first-order perturbation theory with several values of the infrared cutoff. It is shown that with a cutoff of 1 eV, which corresponds to infrared light, the photon capture is several times larger than the $d-t$ fusion rate in the big bang nucleosynthesis in the early universe, makes a noticeable contribution to energy release in tokamaks, and dominates by a few orders of magnitude in laser-direct-driven inertial confinement fusion. No effect on these three environments can be seen if the infrared cutoff is 1 keV. However, with this cutoff the photon absorption in a $d-t$ mixture could become noticeable in future laser facilities at power intensities above ${10}^{18}\mathrm{Watt}/{\mathrm{cm}}^2$. With further increase of the intensity towards ${10}^{27}\mathrm{Watt}/{\mathrm{cm}}^2$ photon capture will dominate even if the first-order perturbation theory breaks down at very large values of the infrared cutoff, around 1 MeV. The development of a nonperturbative approach to $d+t+\gamma \to \alpha +n$ reaction is crucial to capture correctly the physics of low-energy photoabsorption with high-energy release.

We investigate the photoproduction off a proton target in the channel with $K^{+}$ and ${\mathrm{\Sigma }}^0$ in the final state. The model of our choice for description of this process is based on effective Lagrangians at the tree level; it is the so-called isobar model. This formalism was developed previously for description of $K^{+}\mathrm{\Lambda }$ photoproduction, and the aim of this study is to provide an extension of this description towards $\mathrm{\Sigma }$ photoproduction channels. Our fitting strategy has two stages. In the first stage we employ standard ${\chi }^2$ minimization using a set of resonances, based on previous works. In the second stage, we apply a model selection procedure to the same set of resonances using $L_1$ regularization in combination with criteria from information theory, and we obtain a sparser model. This gives us two fits which we compare with data and comment on their behavior. Some of the available data (CLAS differential cross sections at energies $W>2.4\text{GeV}$, SAPHIR differential cross sections, and $C_{x^{\prime }}$ and $C_{z^{\prime }}$ polarizations) are not included in the fits, but are used to test the predictive power of the two models. The sparser model shows better agreement with the unfitted data compared to the full model.

The phenomenological Skyrme energy density functional theory is one of the most popular theories for dealing with finite nuclei and infinite nuclear matter, including neutron star matter. However, the density dependence of the effective masses of common Skyrme parametrizations is completely different from the one found in microscopic calculations. This can have drastic consequences. For instance, in a recent study we reported that in many Skyrme functionals, the neutron Fermi velocity exceeds the speed of light at densities that exist in neutron star cores. To solve this problem, we try to construct new Skyrme parametrizations by including constraints from microscopic calculations of the effective mass in addition to binding energies and charge radii of finite nuclei and different microscopic equations of state of pure neutron matter. We give the parameters of the new Skyrme forces and show that our new effective interactions can successfully describe properties of finite nuclei and nuclear matter (including pure neutron matter, symmetric nuclear matter, and neutron star matter).

We introduce a simple algorithm for projecting on $J=0$ states of a many-body system by performing a series of rotations to remove states with angular momentum projections greater than zero. Existing methods rely on unitary evolution with the two-body operator $J^2$, which when expressed in the computational basis contains many complicated Pauli strings requiring Trotterization and leading to very deep quantum circuits. Our approach performs the necessary projections using the one-body operators $J_x$ and $J_z$. By leveraging the method of Cartan decomposition, the unitary transformations that perform the projection can be parametrized as a product of a small number of two-qubit rotations, with angles determined by an efficient classical optimization. Given the reduced complexity in terms of gates, this approach can be used to prepare approximate ground states of even-even nuclei by projecting onto the $J=0$ component of deformed Hartree-Fock states. We estimate the resource requirements in terms of the universal gate set $\{H,S,\mathrm{CNOT},T\}$ and briefly discuss a variant of the algorithm that projects onto $J=1/2$ states of a system with an odd number of fermions.

The pygmy dipole resonance (PDR) at the low-lying tail of the giant dipole resonance (GDR) is an interesting research subject because it carries important information about the nuclear surface with mixed isoscalar and isovector vibrations in $N>Z$ systems. The present paper investigates the possible existence of the PDR built on excited states in a neutron-rich ${}^{80}\mathrm{Ge}$ nucleus using the phonon damping model (PDM) with and without pairing correlation at zero and finite temperatures. The results obtained within the PDM with exact pairing $(\mathrm{EP}+\text{PDM})$ reveal the appearance of two enhanced $\gamma$ transitions $E_{\gamma }=7.25$ and 7.35 MeV at $T=0.6 \mathrm{MeV}$, which carry the PDR nature and hence imply the possible existence of PDR built on excited states in this nucleus. These two $\gamma$ energies nicely match with a recent experimental observation, thus indicating the crucial role of the inclusion of exact pairing solution in the precise description of low-lying $\gamma$ transitions. The partition-function-based analysis shows that this predicted PDR at $T=0.6 \mathrm{MeV}$ is mainly contributed by the first $2^{+}$ excited state of the ${}^{80}\mathrm{Ge}$ nucleus. The isospin mixing at the nuclear surface is also observed in the investigated PDR at $T=0.6–0.7 \mathrm{MeV}$. The primary mechanism underlying the emergence of the hot PDR is found due to the coupling of GDR phonon to noncollective particle-particle and hole-hole configurations at finite temperatures within the PDM framework, along with the shift in particle-hole excitation energies due to thermal pairing correlations.

Background: Light particle ($\alpha$ particle, proton, and neutron) spectra were used to probe the dynamics of the compound nucleus formation and decay of systems with $A<100$. At high excitation energies, the same compound nucleus was populated, revealing that fusion is hindered in mass-symmetric entrance channels. Over the years, authors have explored diverse explanations for the experimental light particle spectra from fusion-evaporation reactions, contributing to a rich understanding of the field. Notably, prior research has primarily emphasized high-energy excitation of the compound nucleus, highlighting an exciting opportunity to explore the critical dynamics of near-barrier studies.

Purpose: We investigated the evaporation spectra of proton, neutron, and $\alpha$ particles from near-barrier energies to around 25% above-barrier energies. The focus is on understanding the role of entrance channel mass asymmetry, excitation energy, and angular dependence in shaping the reaction dynamics and particle emission processes.

Method: The compound nucleus ${}^{80}\mathrm{Sr}$ was populated via two different entrance channels: ${}^{16}\mathrm{O}$ $+$ ${}^{64}\mathrm{Zn}$ (mass asymmetric system) and ${}^{32}\mathrm{S}$ $+$ ${}^{48}\mathrm{Ti}$ (mass symmetric system). Angular coverage ranged from ${47}^{\circ }$–${113}^{\circ }$ for proton and $\alpha$ particles, and from ${30}^{\circ }$–${120}^{\circ }$ for neutrons. The exclusive spectra were obtained by gating these with evaporation residues obtained in a multiwire proportional counter. The experimental results were compared with cascade and $\mathrm{gemini}++$ statistical model calculations.

Results: Proton spectra exhibited good agreement with statistical model predictions for both mass asymmetric and mass symmetric entrance channels. However, an anomaly was observed in the $\alpha$-particle spectra at near-barrier energy for the mass asymmetric system, necessitating a reduction in the level density parameter to $a=A/10{\mathrm{MeV}}^{-1}$ in cascade calculations to match the experimental data. This suggests enhanced $\alpha$ emission, potentially due to $\alpha$-cluster emission at these energies. Neutron spectra, which are unaffected by emission and transmission barriers, showed deviations from statistical model predictions at higher energies. These deviations necessitated a reduced level density parameter, indicating neutron emission from a compound nucleus at higher temperatures.

Conclusion: Our findings highlight the significant role of pre-equilibrium emission and dynamical effects in nuclear reactions at higher excitation energies for both the systems. The formation, thermal equilibration, and shape equilibration times were calculated using hicol, and decay times using pace, revealing the importance of these processes. Further measurements with $\alpha$-cluster-rich beams and time-dependent Hartree-Fock (TDHF) calculations are suggested to provide deeper insights into these phenomena.

We have calculated the fission fragments' mass distributions for several isotopes of heavy and superheavy nuclei from uranium to flerovium within an improved scission point model. For all considered nuclei, in addition to the standard mass-asymmetric fission mode we have found the mass super-asymmetric mode with the mass of heavy fragments equal 190. For the actinide nuclei, the probability of superasymmetric fission is by six orders of magnitude smaller than for standard asymmetric fission. For the superheavy nuclei this probability is only by two orders of magnitude smaller. In all cases, the superasymmetric scission shapes are dumbbells with the heavy fragment close to a sphere. We have estimated the stability of the light fragment concerning the variation of the neck and found out that sequential ternary fission is not favored energetically. The calculations were carried out with nuclear shape described by generalized Cassinian ovals with six deformation parameters, $\alpha$, ${\alpha }_1$, ${\alpha }_2$, ${\alpha }_3$, ${\alpha }_4$, and ${\alpha }_5$. The configuration at the moment of the neck rupture was defined by fixing $\alpha =0.98$. This value corresponds to a neck radius $r_{\mathrm{neck}}\approx 1.5$ fm.