In this study, the effects of repulsive nucleon-nucleon interactions arising from the Pauli exclusion principle were examined regarding the half-lives of heavy even-even nuclei with $84\le Z\le 92$. The Pauli exclusion principle is applied to our investigations by renormalizing the nucleon-nucleon interactions according to the Bohr-Sommerfeld quantization condition. It is also applied to the double-folding (DF) formalism as a modification term by investigating the kinetic energy variation at the overlapping regions between the densities of the alpha and daughter nuclei. The standard deviation for the calculated half-lives from their corresponded experimental data is 0.340 for the renormalized DF formalism. Its value reduces to 0.309 for the DF formalism modified with the kinetic-energy contribution estimated by the extended Thomas-Fermi approach. The calculated $\alpha$-decay half-lives are more consistent with experimental data if the kinetic-energy contribution is associated with the DF formalism.

Using the idea of the instanton approach to quantum tunneling we try to obtain a method of calculating spontaneous fission rates for nuclei with an odd number of neutrons or protons. This problem has its origin in the failure of the adiabatic cranking approximation which serves as the basis in calculations of fission probabilities. Self-consistent instanton equations, with and without pairing, are reviewed and then simplified to non-self-consistent versions with the phenomenological single-particle potential and seniority pairing interaction. Solutions of instanton-like equations without the pairing and actions they produce are studied for the Woods-Saxon potential along realistic fission trajectories. Actions for unpaired particles are combined with cranking actions for even-even cores and fission hindrance for odd-$A$ nuclei is studied in such a hybrid model. With the mass parameters for neighboring odd-$A$ and even-even nuclei assumed equal, the model shows that freezing the $K^{\pi }$ configuration leads to a large overestimate of the fission hindrance factors. Actions with adiabatic configurations mostly show not enough hindrance; instanton-like actions for blocked nucleons correct this, but not sufficiently.

The thermal description of light nuclei at the chemical freeze-out has been investigated. First, I have verified the equilibration of the light nuclei and then introduced a new method to investigate the light nuclei formation. One can study the proximity between the phase space density of light nuclei ratios and their hadronic constituents, e.g., $\overline{d}/d$ and $(\overline{p}\overline{n}/pn)$. I have found that with the exclusion of the decay feed-down from the hadronic yields in the thermal model, the hadronic representations have good agreement with the light nuclei ratios. I have performed a similar analysis with the ratio of $\mathrm{\Lambda }$ hypernuclei and ${}^3\mathrm{He}$, which is related to the ratio $\mathrm{\Lambda }/p$. In this context, the strangeness population factor $S_3$ has been studied also. These results indicate that the nuclei and hypernuclei formation may occur near the standard chemical freeze-out and before the decay of the hadronic resonances. This method will serve as a guideline to discuss the light nuclei formation and the inclusion of decay into their hadronic constituents.

We optimize $\mathrm{\Delta }$-full nuclear interactions from chiral effective field theory. The low-energy constants of the contact potentials are constrained by two-body scattering phase shifts, and by properties of bound state of $A=2$ to 4 nucleon systems and nuclear matter. The pion-nucleon couplings are taken from a Roy-Steiner analysis. The resulting interactions yield accurate binding energies and radii for a range of nuclei from $A=16$ to $A=132$, and provide accurate equations of state for nuclear matter and realistic symmetry energies. Selected excited states are also in agreement with data.

Lifetimes of excited nuclear states were determined in ${}^{44}\mathrm{Ti}$ using the recoil distance Doppler-shift technique and the Doppler-shift attenuation method. Results from the $K^{\pi }=3^{-}$ band confirm isospin-symmetry breaking for the $3_1^{-}\to 2_1^{+}E1$ transition. The lifetime of the $4_1^{-}$ state differs considerably from the previously known value. Good agreement is found for the $4_1^{+}$ and $6_1^{+}$ level lifetimes with respect to previous values. The experimental values are compared with large-scale shell-model calculations employing established interactions in the $0f1p$ shell, as well as a modern effective Hamiltonian including multiparticle multihole cross-shell configurations. Extended configuration spaces of this shell-model calculation allow for a detailed comparison with newly determined negative-parity states.

We study the structure of ${}_{\mathrm{\Lambda }}{}^9\mathrm{Be}$ within the framework of the three-body $\alpha +\alpha +\mathrm{\Lambda }$ cluster model using the YNG-NF interaction with the Gaussian expansion method. We obtain the energies of bound states as well as energies and decay widths of the resonant states with the complex scaling method. By analyzing our wave functions of bound states and resonant states, we confirm three analog states of ${}_{\mathrm{\Lambda }}{}^9\mathrm{Be}$ pointed out by Bandō and Motoba et al. [T. Motoba, H. Bandō, and K. Ikeda, Prog. Theor. Phys. 70, 189 (1983); T. Motoba, H. Bandō, K. Ikeda, and T. Yamada, Prog. Theor. Phys. Suppl. 81, 42 (1985); H. Bandō, K. Ikeda, and T. Motoba, Prog. Theor. Phys. 69, 918 (1983)], ${}^8\mathrm{Be}$ analog states, ${}_{\mathrm{\Lambda }}{}^9\mathrm{Be}$ genuine states, and ${}^9\mathrm{Be}$ analog states. The new states of ${}_{\mathrm{\Lambda }}{}^9\mathrm{Be}$ are also obtained at a high energy region with broader decay widths.

Background: Eclipse effect of the neutron and the proton in a deuteron target is essential to correctly describe high-energy deuteron scattering. The nucleus-deuteron scattering needs information on not only the nucleus-proton interaction but also the nucleus-neutron interaction, for which no direct measurement of the nucleus-neutron cross sections is available for unstable nuclei.

Purpose: We systematically evaluated the total reaction cross sections on a deuteron target to explore the feasibility of extracting the nucleus-neutron interaction from measurable cross sections.

Methods: High-energy nucleus-deuteron collision is described by the Glauber model, in which the proton and neutron configuration of the deuteron is explicitly taken into account.

Results: Our calculation reproduces available experimental total reaction cross section data on the nucleus-deuteron scattering. The possibility of extracting the nucleus-neutron total reaction cross section from nucleus-deuteron and nucleus-proton total reaction cross sections is explored. The total reaction cross sections on proton, neutron, and deuteron targets can be expressed, to good accuracy, in terms of the nuclear matter radius and the neutron skin thickness. Incident-energy dependence of the total reaction cross sections is examined.

Conclusions: The total reaction cross section on a deuteron target includes information on both the nucleus-neutron and the nucleus-proton profile functions. Measuring the cross sections by deuteron and proton targets is a promising tool to extract the nuclear size properties.

Prompt photon production in hadronic collisions at energies available at RHIC and at the LHC is investigated within the QCD color dipole approach. Predictions for the nuclear modification factor in $pA$ collisions are evaluated based on the parton saturation framework, and the results are compared with the experimental measurements as a function of the photon transverse momentum at different rapidity bins. The reliability of the models is performed with the data from the PHENIX, ATLAS, and ALICE Collaborations. Moreover, we show that the observed $x_T$ scaling of prompt photon production in $pp$ and $pA$ collisions can positively be addressed in the QCD color dipole formalism.

The upper bound of the speed of sound in dense nuclear matter is one of the most interesting but still unsolved problems in nuclear physics. Theoretical studies in connection with recent observational data of isolated neutron stars as well as binary neutron stars systems offer an excellent opportunity to shed light on this problem. In the present work, we suggest a method to directly relate the measured tidal deformability (polarizability) of binary neutron stars system (before merger) to the maximum neutron star mass scenario and possible upper bound on the speed of sound. This method is based on the simple but efficient idea that while the upper limit of the effective tidal deformability favors soft equations of state, the recent high measured values of neutron star mass favor stiff ones. In the present work, first, using a simple well established model we parametrize the stiffness of the equation of state with the help of the speed of sound. Second, in comparison with the recent observations by LIGO/VIRGO collaboration of two events, GW170817 and GW190425, we suggest possible robust constraints. Moreover, we evaluate and postulate, in the framework of the present method, what kind of future measurements could help us to improve the stringent of the constraints on the neutron star equation of state.

Light clusters such as $\alpha$ particles and deuterons are predicted to occur in hot nuclear matter as encountered in intermediate-energy heavy-ion collisions and protoneutron stars. To examine the in-medium properties of such light clusters, we consider a much simplified system in which, like an impurity, a single $\alpha$ particle is embedded in a zero-temperature, dilute gas of noninteracting neutrons. By adopting a non-self-consistent ladder approximation for the effective interaction between the impurity and the gas, which is often used for analyses of Fermi polarons in a gas of ultracold atoms, we calculate the quasiparticle properties of the impurity, i.e., the energy shift, effective mass, quasiparticle residue, and damping rate.

New high precision total and differential cross sections are reported for the $dp\to {}^3\mathrm{He}\eta$ reaction close to threshold. The measurements were performed using the magnetic spectrometer ANKE, which is an internal fixed target facility at the COSY cooler synchrotron. The data were taken for deuteron beam momenta between $3.14641\text{GeV}/c$ and $3.20416\text{GeV}/c$, which corresponds to the range in excess energy $Q$ for this reaction between $1.14\text{MeV}$ and $15.01\text{MeV}$. The normalization was established through the measurement in parallel of deuteron-proton elastic scattering and this was checked through the study of the $dp\to {}^3\mathrm{He}{\pi }^0$ reaction. The previously indicated possible change of sign of the slope of the differential cross sections near the production threshold, which could be explained by a rapid variation of the $s$- and $p$-wave interference term, is not confirmed by the new data. The energy dependence of the total cross section and the ${90}^{\circ }$ slope parameter are well explained by describing the final state interaction in terms of a complex Jost function and the results are significant in the discussion of $\eta$-mesic nuclei. In combination with recently published WASA-at-COSY data [P. Adlarson et al., Phys. Lett. B 782, 297 (2018)], a smooth variation of the slope parameter is achieved up to an excess energy of $80.9\text{MeV}$.

A comprehensive study of the isotope ${}^{178}\mathrm{Au}$ has been made at the CERN-ISOLDE facility, using resonance laser ionization. Two long-lived states in ${}^{178}\mathrm{Au}$ were identified—a low-spin ground state and a high-spin isomer—each of which were produced as pure beams. Using the ISOLTRAP precision Penning trap, the excitation energy of the isomeric state in ${}^{178}\mathrm{Au}$ was determined to be $E^{*}=189\left(14\right)\mathrm{keV}$. The $\alpha$-decay fine structure patterns of the two states were studied using the Windmill decay station, providing information on the low-lying states in the daughter nucleus ${}^{174}\mathrm{Ir}$. Nuclear spin assignments of $I\left({}^{178}\mathrm{Au}^g\right)=(2,3)$ and $I\left({}^{178}\mathrm{Au}^m\right)=(7,8)$ are made based on the observed $\beta$-decay feeding and hyperfine structure intensity patterns. These spin assignments are used for fitting the hyperfine structures of the two states from which values for the magnetic dipole moments are extracted. The extracted moments are compared with calculations using additivity relations to establish the most probable configurations for ${}^{178}\mathrm{Au}^{g,m}$.

Excited states of neutron-rich iodine isotopes ${}^{130\text{–}134}\mathrm{I}$ above the high-spin isomers have been identified using prompt-delayed $\gamma$-ray spectroscopy. The iodine isotopes were produced as fission fragments of fusion-fission and transfer induced fission of ${}^9\mathrm{Be}({}^{238}\text{U},f$) at a beam energy of 6.2 MeV/u. The complete $(A,Z)$ identification was obtained using the large acceptance magnetic spectrometer $\mathrm{VAMOS}++$. The AGATA $\gamma$-ray tracking array was used to detect the prompt $\gamma$ rays while the delayed $\gamma$ rays (in the time range of 100 ns to 200 $\mu \mathrm{s}$) from the isomeric states were identified by the EXOGAM segmented clover detectors, placed behind the focal plane of the $\mathrm{VAMOS}++$ spectrometer. The high-spin states above the $\left(8^{-}\right)$ isomers in ${}^{130,132}\mathrm{I}$ were populated for the first time, and a new isomer in ${}^{132}\mathrm{I}$ was identified. A new $\gamma$-ray transition was also assigned to the level structure of ${}^{134}\mathrm{I}$. Prompt transitions above the $19/2^{-}$ isomer were identified in ${}^{131,133}\mathrm{I}$, for the first time. The level structures are interpreted in terms of the systematics of odd-$Z$ nuclei above the $Z=50$ shell closure and large-scale shell model calculations.

Background: The structure of ${}^{26}\mathrm{O}$ is currently being investigated on both theoretical and experimental fronts. It is well established that it is unbound and the resonance parameters are fairly well known. The theoretical analysis may involved two- and three-body interactions as well as correlations with the continuum spectrum of energy.

Purpose: In order to properly assess the structure of the ground and excited states, it is imperative to include a large single-particle representation with the right asymptotic behavior. The purpose of this paper is to provide details of the single-particle continuum configurations of the ground and excited $0^{+}$ states.

Method: We use a large complex energy single-particle basis, formed by resonances and complex energy scattering states, the so-called Berggren basis, and a separable interaction, which is convenient to solve in a large model space.

Results: Three $0^{+}$ states were found in the complex energy plane. Changes in the resonant parameters, i.e., energy and width, were analyzed as a function of strength of the residual interaction. It is shown how a subtle difference in the interaction could change the unbound character of ${}^{26}\mathrm{O}$ into a Borromean nucleus.

Conclusions: Only one of the two excited states can be considered as a candidate for a physical meaningful resonance. The calculated occupation probabilities are in agreement with other theoretical approaches although the calculated half-life is three orders of magnitude smaller than the experimental one.

Excited states in ${}^{73,75}\mathrm{Ni}$ were investigated through the $\beta$ decay of ${}^{73,75}\mathrm{Co}$ in an experiment performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). The experimental results extended the level scheme of ${}^{73}\mathrm{Ni}$ to 3.2-MeV excitation energy and provided the experimental information on excited states in ${}^{75}\mathrm{Ni}$. The $\beta$-delayed neutron branching ratio for ${}^{73}\mathrm{Co}$ was obtained. The experimental results are discussed in comparison with shell-model calculations.

An approach is outlined to constructing an optical potential that includes the effects of antisymmetry and target recoil. It is based on the retarded Green's function, which could make it a better starting point for applications to direct nuclear reactions, particularly when extended to coupled channels. Its form retains a simple connection to folding potentials, even in the presence of three-body forces.

Measurements of jet substructure in heavy-ion collisions may provide key insight into the nature of jet quenching in the quark-gluon plasma. Jet grooming techniques from high-energy physics have been applied to heavy-ion collisions in order to isolate theoretically controlled jet observables and explore possible modification to the hard substructure of jets. However, the grooming algorithms used have not been tailored to the unique considerations of heavy-ion collisions, in particular to the experimental challenge of reconstructing jets in the presence of a large underlying event. We report a set of simple studies illustrating the impact of the underlying event on identifying groomed jet splittings in heavy-ion collisions, and on associated groomed jet observables. We illustrate the importance of the selection of the grooming algorithm, as certain groomers are more robust against these effects, while others, including those commonly used in heavy-ion collisions, are susceptible to large background effects, which, when uncontrolled, can mimic a jet-quenching signal. These experimental considerations, along with appropriate theoretical motivation, provide input to the choice of grooming algorithms employed in heavy-ion collisions.

Lattice simulations are the only viable way to obtain ab initio quantum chromodynamics (QCD) predictions for low energy nuclear physics. These calculations are done, however, in a finite box and therefore extrapolation is needed to get the free space results. Here, we use nuclear effective field theory (EFT), designed to provide a low energy description of QCD using baryonic degrees of freedom, to extrapolate the lattice results from finite to infinite volumes. To this end, we fit the EFT to the results calculated with nonphysical high quark masses and solve it with the stochastic variational method in both finite and infinite volumes. Moreover, we perform similar EFT calculations of the physical point and predict the finite-volume effects to be found in future lattice QCD calculations for atomic nuclei with mass number $A\le 4$.

Background: Detailed information on the low-lying dipole response in atomic nuclei along isotonic or isotopic chains is well suited to systematically investigate the structure and evolution of the pygmy dipole resonance (PDR). Moreover, the dipole strength below and around the neutron separation energy $S_n$ has impact on statistical model calculations for nucleosynthesis processes.

Purpose: The photon strength function (PSF) of ${}^{87}\mathrm{Rb}$, which is directly connected to the photoabsorption cross section, is a crucial input for statistical model calculations constraining the Maxwellian-averaged cross section (MACS) of the neutron capture of the unstable $s$-process branching-point nucleus ${}^{86}\mathrm{Rb}$. Within this work, the photoabsorption cross section is investigated.

Methods: The photoabsorption cross section of the $N=50$ nucleus ${}^{87}\mathrm{Rb}$ was determined from photon-scattering experiments via the nuclear resonance fluorescence (NRF) technique. Bremsstrahlung beams at the $\gamma \mathrm{ELBE}$ facility in conjunction with monoenergetic photon beams at the $\mathrm{HI}\gamma \mathrm{S}$ facility were used to determine the integrated cross sections $I_s$ of isolated states as well as the averaged cross section as function of the excitation energy. Decays to the ground state were disentangled from decays to first low-lying excited states. Statistical and experimental approaches for the $\gamma$-decay properties at various excitation energies were applied. The linearly polarized photon beams at $\mathrm{HI}\gamma \mathrm{S}$ provide information on the ratio of electric and magnetic type of radiation.

Results: Within this work, more than 200 ground-state decays and associated levels in ${}^{87}\mathrm{Rb}$ were identified. Moreover, transitions below the sensitivity limit of the state-by-state analysis were taken into account via a statistical approach from the bremsstrahlung data as well as model-independently from the $\mathrm{HI}\gamma \mathrm{S}$ data. The photoabsorption cross sections at various excitation energies were determined. The dipole response between 6 and 10 MeV of ${}^{87}\mathrm{Rb}$ is in agreement with assuming contributions of electric multipolarity, only.

Conclusions: The photoabsorption cross section of ${}^{87}\mathrm{Rb}$ does not contradict with the trend of decreasing $E1$ strength with increasing proton number along the $N=50$ isotonic chain but might also be associated with a constant trend. The experimental $\gamma$ decay at various excitation energies of the $\mathrm{HI}\gamma \mathrm{S}$ data supports the statistical approach but does not provide a stringent proof due to the limited sensitivity in the decay channels. The additional $E1$ strength observed in the present experiments significantly enhances the MACSs compared only to recent microscopic $\mathrm{HFB}+\mathrm{QRPA}$ (Hartree-Fock-Bogoliubov plus quasiparticle random-phase approximation) calculations using the D1M interaction. Moreover, theoretical estimations provided by the KADoNiS project could be significantly improved.