We develop the single-channel local potential for the $\overline{K}N$ system, which is applicable to quantitative studies of $\overline{K}$ bound states in nuclei. Because the high-precision measurement of the kaonic hydrogen by SIDDHARTA reduces the uncertainty of the $\overline{K}N$ amplitude below the $\overline{K}N$ threshold, the local potential should be calibrated in a wide energy region. We establish a new method to construct the local potential focusing on the behavior of the scattering amplitude in the complex energy plane. Applying this method, we construct the $\overline{K}N$ potential based on the chiral coupled-channel approach with the SIDDHARTA constraint. The wave function from the new potential indicates the $\overline{K}N$ molecular structure of $\mathrm{\Lambda }\left(1405\right)$.

The nucleon exchange mechanism is investigated in the central collisions of ${}^{40}\mathrm{Ca}+{}^{238}\mathrm{U}$ and ${}^{48}\mathrm{Ca}+{}^{238}\mathrm{U}$ systems near the quasifission regime in the framework of the stochastic mean-field (SMF) approach. Sufficiently below the fusion barrier, a dinuclear structure in the collisions is maintained to a large extent. Consequently, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Diffusion coefficients for proton and neutron exchange are determined from the microscopic basis of the SMF approach in the semiclassical framework. Calculations show that after a fast charge equilibration the system drifts toward symmetry over a very long interaction time. Large dispersions of proton and neutron distributions of the produced fragments indicate that the diffusion mechanism may help to populate heavy transuranium elements near the quasifission regime in these collisions.

Nuclei colliding at very high energy create a strong, quasiclassical gluon field during the initial phase of their interaction. We present an analytic calculation of the initial space-time evolution of this field in the limit of very high energies using a formal recursive solution of the Yang-Mills equations. We provide analytic expressions for the initial chromoelectric and chromomagnetic fields and for their energy-momentum tensor. In particular, we discuss event-averaged results for energy density and energy flow as well as for longitudinal and transverse pressure of this system. For example, we find that the ratio of longitudinal to transverse pressure very early in the system behaves as $p_L/p_T=-[1-\frac{3}{2a}{\left(Q\tau \right)}^2]/[1-\frac{1}{a}{\left(Q\tau \right)}^2]+\mathcal{O}{\left(Q\tau \right)}^4$, where $\tau$ is the longitudinal proper time, $Q$ is related to the saturation scales $Q_s$ of the two nuclei, and $a=ln(Q^2/{\widehat{m}}^2)$ with $\widehat{m}$ a scale to be defined later. Our results are generally applicable if $\tau \lesssim 1/Q$. As already discussed in a previous paper, the transverse energy flow $S^i$ of the gluon field exhibits hydrodynamiclike contributions that follow transverse gradients of the energy density ${\nabla }^i\varepsilon$. In addition, a rapidity-odd energy flow also emerges from the non-Abelian analog of Gauss' law and generates nonvanishing angular momentum of the field. We discuss the space-time picture that emerges from our analysis and its implications for observables in heavy-ion collisions.

Background: Multiple large collaborations are currently searching for neutrinoless double-$\beta$ decay, with the ultimate goal of differentiating the Majorana-Dirac nature of the neutrino.

Purpose: Investigate the feasibility of resonant neutrinoless double-electron capture, an experimental alternative to neutrinoless double-$\beta$ decay.

Method: Two clover germanium detectors were operated underground in coincidence to search for the de-excitation $\gamma$ rays of ${}^{156}\mathrm{Gd}$ following the neutrinoless double-electron capture of ${}^{156}\mathrm{Dy}$. 231.95 d of data were collected at the Kimballton underground research facility with a 231.57 mg enriched ${}^{156}\mathrm{Dy}$ sample.

Results: No counts were seen above background and half-life limits are set at $O\left({10}^{16}\text{–}{10}^{18}\right)$ yr for the various decay modes of ${}^{156}\mathrm{Dy}$.

Conclusion: Low background spectra were efficiently collected in the search for neutrinoless double-electron capture of ${}^{156}\mathrm{Dy}$, although the low natural abundance and associated lack of large quantities of enriched samples hinders the experimental reach.

I investigate ${}^{10}\mathrm{B}+\alpha$-cluster states of ${}^{14}\mathrm{N}$ with a ${}^{10}\mathrm{B}+\alpha$-cluster model. Near the $\alpha$-decay threshold energy, I obtain $K^{\pi }=3^{+}$ and $K^{\pi }=1^{+}$ rotational bands having ${}^{10}\mathrm{B}\left(3^{+}\right)+\alpha$ and ${}^{10}\mathrm{B}\left(1^{+}\right)+\alpha$ components, respectively. I assign the bandhead state of the $K^{\pi }=3^{+}$ band to the experimental $3^{+}$ at $E_x=13.19$ MeV of ${}^{14}\mathrm{N}$ observed in $\alpha$ scattering reactions by ${}^{10}\mathrm{B}$ and show that the calculated $\alpha$-decay width is consistent with the experimental data. I discuss an $\alpha$-cluster motion around the ${}^{10}\mathrm{B}$ cluster and show that the $K^{\pi }=3^{+}$ and $K^{\pi }=1^{+}$ rotational bands contain an enhanced component of a linear-chain $3\alpha$ configuration, in which an $\alpha$ cluster is localized in the longitudinal direction around the deformed ${}^{10}\mathrm{B}$ cluster.

In this article, I calculate the contributions of nuclear-matter-induced condensates up to dimension 5, take into account the next-to-leading order contributions of the nuclear-matter-induced quark condensate, study the properties of the scalar, pseudoscalar, vector, and axial-vector heavy mesons in nuclear matter with the QCD sum rules in a systematic way, and obtain the shifts of the masses and decay constants. Furthermore, I study the heavy-meson–nucleon scattering lengths as a byproduct, and conclude qualitatively about the possible existence of heavy-meson–nucleon bound states.

Reduced quadrupole transition probabilities for low-lying transitions in neutron-rich ${}^{84,86}\mathrm{Se}$ are investigated with a recoil distance Doppler shift (RDDS) experiment. The experiment was performed at the Istituto Nazionale di Fisica Nucleare (INFN) Laboratori Nazionali di Legnaro using the Cologne Plunger device for the RDDS technique and the AGATA Demonstrator array for the $\gamma$-ray detection coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In ${}^{86}\mathrm{Se}$ the level lifetime of the yrast $2_1^{+}$ state and an upper limit for the lifetime of the $4_1^{+}$ state are determined for the first time. The results of ${}^{86}\mathrm{Se}$ are in agreement with previously reported predictions of large-scale shell-model calculations using Ni78-I and Ni78-II effective interactions. In addition, intrinsic shape parameters of lowest yrast states in ${}^{86}\mathrm{Se}$ are calculated. In semimagic ${}^{84}\mathrm{Se}$ level lifetimes of the yrast $4_1^{+}$ and $6_1^{+}$ states are determined for the first time. Large-scale shell-model calculations using effective interactions Ni78-II, JUN45, jj4b, and jj4pna are performed. The calculations describe $B(E2;2_1^{+}\to 0_1^{+})$ and $B(E2;6_1^{+}\to 4_1^{+})$ fairly well and point out problems in reproducing the experimental $B(E2;4_1^{+}\to 2_1^{+})$.

Photodisintegration of ${}^9\mathrm{Be}$ through the $1/2^{+}$ state near neutron threshold and cluster dipole resonance below giant dipole resonance was measured with quasi-monochromatic $\gamma$-ray beams produced in the inverse Compton scattering of laser photons. The cross section for the $1/2^{+}$ state is revisited, being consistent with the 2001 data. The cross section for the cluster dipole resonance is consistent with the cluster dipole sum-rule which however degenerates for the two-body $\left(n\text{−}{}^8\mathrm{Be}\right)$ and three-body $\left(n\text{−}\alpha \text{−}\alpha \right)$ configurations.

High spin states in ${}^{73}\mathrm{As}$ have been investigated through the fusion-evaporation reaction ${}^{64}\mathrm{Ni}({}^{12}\mathrm{C},p2n){}^{73}\mathrm{As}$ with an incident beam energy of 55 MeV. The level scheme has been extended up to $J^{\pi }=(37/2^{-})$ and excitation energy $\sim 8.7$ MeV with the addition of 30 new $\gamma$-ray transitions. The microscopic origins of the observed positive- and negative-parity band structures are discussed in the context of the particle rotor model. Nucleon alignments and shape evolution with increasing angular momentum are discussed in the framework of the cranked shell model and relativistic mean-field calculations. The results offer insight into the nature of the observed band structures and indicate prolate-oblate shape coexistence between positive- and negative-parity bands at low spin.

Background: Nuclear collective rotations have been successfully described by the cranking Hartree-Fock-Bogoliubov (HFB) model. However, for rotational sidebands which are built on intrinsic excited configurations, it may not be easy to find converged cranking HFB solutions. The nonconservation of the particle number in the BCS pairing is another shortcoming. To improve the pairing treatment, a particle-number-conserving (PNC) pairing method was suggested. But the existing PNC calculations were performed within a phenomenological one-body potential (e.g., Nilsson or Woods-Saxon) in which one has to deal the double-counting problem.

Purpose: The present work aims at an improved description of nuclear rotations, particularly for the rotations of excited configurations, i.e., sidebands.

Methods: We developed a configuration-constrained cranking Skyrme Hartree-Fock (SHF) calculation with the pairing correlation treated by the PNC method. The PNC pairing takes the philosophy of the shell model which diagonalizes the Hamiltonian in a truncated model space. The cranked deformed SHF basis provides a small but efficient model space for the PNC diagonalization.

Results: We have applied the present method to the calculations of collective rotations of hafnium isotopes for both ground-state bands and sidebands, reproducing well experimental observations. The first up-bendings observed in the yrast bands of the hafnium isotopes are reproduced, and the second up-bendings are predicted. Calculations for rotational bands built on broken-pair excited configurations agree well with experimental data. The band-mixing between two $K^{\pi }=6^{+}$ bands observed in ${}^{176}\mathrm{Hf}$ and the $K$ purity of the ${}^{178}\mathrm{Hf}$ rotational state built on the famous 31 yr $K^{\pi }={16}^{+}$ isomer are discussed.

Conclusions: The developed configuration-constrained cranking calculation has been proved to be a powerful tool to describe both the yrast bands and sidebands of deformed nuclei. The analyses of rotational moments of inertia help to understand the structures of nuclei, including rotational alignments, configurations, and competitions between collective and single-particle excitations.

We propagate the statistical uncertainty of experimental $NN$ scattering data into the binding energy of ${}^3\text{H}$ and ${}^4\text{He}$. We also study the sensitivity of the magnetic moment and proton radius of the ${}^3\text{H}$ to changes in the $NN$ interaction. The calculations are made with the no-core full configuration method in a sufficiently large harmonic oscillator basis. For those light nuclei we obtain $\mathrm{\Delta }{E}^{\mathrm{stat}}\left({}^3\text{H}\right)=0.015\mathrm{MeV}$ and $\mathrm{\Delta }{E}^{\mathrm{stat}}\left({}^4\text{He}\right)=0.055\mathrm{MeV}$.

The excitation spectra in the deformed nucleus ${}^{232}\mathrm{U}$ have been studied by means of the ($p,t$) reaction, using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons were measured for 162 excitations seen in the triton spectra up to 3.25 MeV. $0^{+}$ assignments are made for 13 excited states by comparison of experimental angular distributions with the calculated ones using the chuck3 code. Assignments up to spin $6^{+}$ are made for other states. Sequences of states are selected which can be treated as rotational bands. Moments of inertia have been derived from these sequences, whose values may be considered as evidence of the two- or one-phonon nature of these $0^{+}$ excitations. Experimental data are compared with interacting boson model and quasiparticle-phonon model calculations.

In this paper we study the low-lying states of the ${}^{132}\mathrm{Ba}$ nucleus within the nucleon-pair approximation, with our focus on the mechanism of band-crossing in the yrast band and two side bands headed by the $5_1^{-}$ and $6_1^{-}$ states, respectively. Two mechanisms of the back-bending phenomenon in the yrast band previously suggested, i.e., the contribution of noncollective pairs with two $h_{11/2}$ neutron holes coupled to various spins (called $H$ pairs for short) and the coupling of two neutron pairs with negative parity, are reconciled on the same footing and are found to be complementary in the description of low-lying states of the ${}^{132}\mathrm{Ba}$ nucleus. This is carried out by nucleon-pair-approximation calculation in the proton configuration space constructed by collective $SD$ pairs, coupled with the neutron configuration space constructed by $SD$ pairs, $H$ pairs, and collective negative-parity pairs of spin from 4 to 7. Our calculations show that back-bending exists in the ${13}_1^{-}$ state in the band based on the $5_1^{-}$ state, and in the ${14}_1^{-}$ state in the band based on the $6_1^{-}$ state, in addition to the back-bending in the ${10}_1^{+}$ state in the yrast band. These back-bendings are interpreted in terms of the ${\left(\nu h_{11/2}\right)}^{-2}$ alignment. We also perform calculations in a number of selected subspaces for neutron configuration. We show that the states above the corresponding back-bendings are reasonably represented by the negative-parity neutron pairs and better represented by the spin-10 $H$ pair. In order to reproduce the experimental value of $B(E2,{10}_1^{+}\to 8_1^{+})$, the configurations of negative-parity neutron pairs are essential.

Spectra of two-step $\gamma$ cascades following neutron capture in ${}^{155,157}\mathrm{Gd}$ are measured using the two-Ge-detector facility installed at the thermal neutron beam of the research reactor LVR-15 at Řež. The main objective of this experiment is to obtain new information on photon strength functions, with the emphasis on the role of $M1$ scissors-mode vibration. An analysis of accumulated $\gamma$-ray spectra, made within the statistical model, leads to the conclusion that the scissors mode significantly affects $\gamma$ decay of all states of studied nuclei. Experimental data are compared to photon strength functions deduced from other experiments. Agreement of our results with those obtained from DANCE measurement of $\gamma$ spectra following resonance neutron capture is obtained.

For low energy reaction studies involving radioactive ion beams, the experimental reaction yields are generally small due to the low intensity of the beams. For this reason, the stacked target technique has been often used to measure excitation functions. This technique offers considerable advantages since the reaction cross-section at several energies can be simultaneously measured. In a further effort to increase yields, thick targets are also employed. The main disadvantage of the method is the degradation of the beam quality as it passes through the stack due to the statistical nature of energy loss processes and any nonuniformity of the stacked targets. This degradation can lead to ambiguities of associating effective beam energies to reaction product yields for the targets within the stack and, as a consequence, to an error in the determination of the excitation function for the reaction under study. A thorough investigation of these ambiguities is reported, and a best practice procedure of analyzing data obtained using the stacked target technique with radioactive ion beams is recommended. Using this procedure a re-evaluation is reported of some previously published sub-barrier fusion data in order to demonstrate the possibility of misinterpretations of derived excitation functions. In addition, this best practice procedure has been used to evaluate, from a new data set, the sub-barrier fusion excitation function for the reaction ${}^6\mathrm{Li}+{}^{120}\mathrm{Sn}$.

Using different Skyrme interactions, we have carried out a comparative analysis of fusion barriers for a wide range of interacting nuclei in the framework of semiclassical Skyrme energy density formalism. The results of our calculations reveal that SVI, SII, and SIII Skyrme forces are able to reproduce the empirical values of barrier heights with higher accuracy than the other considered forces in this formalism. It is also shown that the calculated nucleus-nucleus potentials derived from such Skyrme interactions are able to explain the fusion cross sections at energies near and above the barrier.

Exact Faddeev-type three-body equations are applied to the study of the proton transfer reactions $(d,n)$ in the system consisting of a nuclear core and two nucleons. The integral equations for the three-body transition operators are solved in the momentum-space framework including the Coulomb interaction via the screening and renormalization method. For a weakly bound final nucleus the calculation of the $(d,n)$ reaction is more demanding in terms of the screening radius as compared to the $(d,p)$ reaction. Well-converged differential cross section results are obtained for ${}^7\text{Be}(d,n){}^8\text{B}$, ${}^{12}\text{C}(d,n){}^{13}\text{N}$, and ${}^{16}\text{O}(d,n){}^{17}\text{F}$ reactions. A comparison with the corresponding $(d,p)$ reactions is made. The calculations fail to reproduce the shape of the angular distribution for reactions on ${}^{12}\text{C}$ but provide quite successful description for reactions on ${}^{16}\text{O}$, especially for the transfer to the ${}^{17}\text{F}$ excited state $1/2^{+}$ when using a nonlocal optical potential.

Data from an experiment on the ${}^{197}\text{Au}+{}^{197}\text{Au}$ reaction at $23A\mathrm{MeV}$ are analyzed with an aim to find signatures of exotic nuclear configurations such as toroid-shaped objects. The experimental data are compared with predictions of the etna code, dedicated to look for such configurations, and with the quantum molecular dynamics (QMD) model. A novel criterion of selecting events possibly resulting from the formation of exotic freeze-out configurations, “the efficiency factor,” is tested. Comparison between experimental data and model predictions may indicate the formation of flat and/or toroidal nuclear systems.

Using the coalescence model based on the phase-space distributions of protons, neutrons, $\mathrm{\Lambda }\mathrm{s}$, and their antiparticles from a multiphase transport (AMPT) model, we study the production of light nuclei ($\mathrm{H}$, $\mathrm{H}$, $\mathrm{He}$, $\mathrm{H}$) and their antinuclei in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. The resulting transverse momentum spectra, elliptic flows, and coalescence parameters for these nuclei are presented and compared with available experimental data. We also show the constituent number scaled elliptic flows of these nuclei and discuss its implications.