The extended quantum molecular dynamics (EQMD) model is one of the few quantum molecular dynamics (QMD)-like transport approaches that can be used to study the effective clustering structure as well as heavily deformed nuclei in both ground state nuclei and nuclear reactions. However, there are only two parameter sets that lead to hard incompressibility for long times. The aim of the present work is to obtain a soft equation of state (EoS) in the EQMD model. In this context, we take the isoscalar giant monopole resonance (ISGMR), which is sensitive to the EoS, as an example to check our work. By introducing a kind of standard Skyrme energy density functional with different parameter sets, such as SkP, SkT1, and SKXce, whose incompressibility value ranges from 200 to 268 MeV, the ISGMR of ${}^{208}\mathrm{Pb}$ and other nuclei are studied. When the SkP parameter sets are adopted, our new soft interaction in the EQMD model gives reasonable agreement with the experimental data in the heavy ion regime.

The elastic $p\text{−}{}^{12}\mathrm{C}$ scattering at low energies is studied by using a cluster effective field theory (EFT), where the low-lying resonance states ($s_{1/2}, p_{3/2}, d_{5/2}$) of ${}^{13}\mathrm{N}$ are treated as pertinent degrees of freedom. The low-energy constants of the Lagrangian are expressed in terms of the Coulomb-modified effective range parameters, which are determined to reproduce the experimental data for the differential cross sections. The resulting theoretical predictions agree very well with the experimental data. The resulting theory is shown to give us almost identical phase shifts as obtained from the $R$-matrix approach and predict the experimental analyzing power data. The role of the ground state of ${}^{13}\mathrm{N}$ below the threshold and the next-to-leading order in the EFT power counting are also discussed.

Interpreting the data of nuclear experiments and astrophysical observations requires advanced theoretical models. At this point, it is of particular importance to develop a unified theoretical framework to describe these experiments and observations based on same effective nuclear interactions. Based on the so-called Skyrme pseudopotential up to next-to-next-to-next-to-leading order, we construct a series of extended Skyrme interactions by modifying the density-dependent term and fitting the empirical nucleon optical potential up to above 1 GeV, the empirical properties of isospin symmetric nuclear matter, the microscopic calculations of pure neutron matter and the properties of neutron stars from astrophysical observations. The modification of the density-dependent term in the extended Skyrme interactions follows the idea of Fermi momentum expansion and this leads to a highly flexible density behavior of the symmetry energy. In particular, the values of the density slope parameter $L$ of the symmetry energy for the new extended Skyrme interactions range from $L=-5$ MeV to $L=125$ MeV by construction, to cover the large uncertainty of the density dependence of the symmetry energy. Furthermore, to consider the effects of isoscalar and isovector nucleon effective masses, we adjust the momentum dependence of the single-nucleon optical potential and the symmetry potential of these new extended Skyrme interactions and construct a parameter set family, by which we systematically study the impacts of the symmetry energy and the nucleon effective masses on the properties of nuclear matter and neutron stars. The new extended Skyrme interactions constructed in the present work will be useful to determine the equation of state of isospin asymmetric nuclear matter, especially the symmetry energy, as well as the nucleon effective masses and their isospin splitting, in transport model simulations for heavy-ion collisions, nuclear structure calculations and neutron star studies.

In the 1970s, an unexpected transverse $\mathrm{\Lambda }$ polarization in unpolarized proton-beryllium collisions was discovered, which initiated extensive studies on spin phenomena in high-energy physics. Over the past five decades, similar transverse $\mathrm{\Lambda }$ polarization has been observed across various collision systems, including lepton-hadron deep-inelastic scattering, hadron-hadron collisions, and electron-positron collisions. Despite numerous promising theoretical models, the fundamental mechanism underlying this polarization phenomenon remains inconclusive to this day. However, in both longitudinally and transversely polarized lepton-hadron and hadron-hadron collisions, it is found that the $\mathrm{\Lambda }$ hyperon is not polarized with respect to the initial parton spin direction. How the $\mathrm{\Lambda }$ hyperon acquires its spin has become one of the most crucial questions to address in order to resolve this puzzle. In this paper, I propose to use an exclusive process that can be measured at the Electron-Ion Collider, the deep exclusive meson production, to explicitly test the mechanism of $\mathrm{\Lambda }$ polarization. The outcomes of this experimental measurement are anticipated to unveil the dominant mechanism by which $\mathrm{\Lambda }$ obtains its spin, eliminating many of the ambiguities that have been encountered in previous studies. Finally, experimental challenges and requirements are discussed.

We study the QCD equation of state and the chiral condensate using the hadron resonance gas model with repulsive mean-field interactions. We find that the repulsive interactions improve the agreement with the lattice results on the derivatives of the pressure with respect to the baryon chemical potential up to eighth order. From the temperature dependence of the chiral condensate we estimate the crossover temperature as a function of baryon chemical potential, $T_{pc}\left({\mu }_B\right)$. We find that the chiral crossover line starts to deviate significantly from the chemical freeze-out line already for ${\mu }_B>400\mathrm{MeV}$. Furthermore, we find that the chiral pseudocritical line can be parametrized as $T_{pc}\left({\mu }_B\right)/T_{pc}\left(0\right)=1-{\kappa }_2{[{\mu }_B/T_{pc}\left(0\right)]}^2-{\kappa }_4{[{\mu }_B/T_{pc}\left(0\right)]}^4$ with ${\kappa }_2=0.0150\left(2\right)$ and ${\kappa }_4=3.1\left(6\right)\times {10}^{-5}$, which are in agreement with lattice QCD results for small values of ${\mu }_B$. For the first time we find a tiny but nonzero value of ${\kappa }_4$ in our study.

The developed Faddeev three-body equations are solved to search for bound-state solutions of a phi-meson $\left(\varphi \right)$ and two-nucleon $\left(NN\right)$ system. We employed the newly published spin $3/2 N\text{−}\varphi$ potential based on $\left(2+1\right)$-flavor lattice QCD simulations near the physical point and the realistic $NN$ Malfliet-Tjon (MT) potential. Our numerical calculations for the $\left(I\right)J^{\pi }=\left(0\right)2^{-}\varphi \text{−}d$ system in maximum spin lead to a ground state binding energy of about 7 MeV and a matter radius of about 8 fm. Our results indicate the possibility of the formation of new nuclear clusters.

I investigate whether it is possible to generate bound states from resonances or virtual states through first-order perturbation theory. Using contact-type potentials as those appeared in pionless effective field theory, I show that it is possible to obtain negative-energy states by sandwiching a next-to-leading order interaction with the leading-order (LO) wave functions, under the presence of LO resonances or virtual states. However, at least under the framework of time-independent Schrödinger equation and Hermitian Hamiltonian, there is an inability to create bound states with structure similar to those formed by the nonperturbative treatments.

Background: The existence of $\alpha$ (${}^4\mathrm{He}$ nucleus) clustering in the medium-mass region of nuclear systems is a fundamental and intriguing question. However, the recent analysis of the $\alpha$ knockout reaction on ${}^{48}\mathrm{Ti}$ [Phys. Rev. C 103, L031305 (2021)] poses a puzzle: The microscopic wave function gives an $\alpha$ knockout cross section that is two orders of magnitude smaller than the experiment, while basic nuclear properties such as the charge radius and the electromagnetic transition probabilities are well explained.

Purpose: The ground-state structure of ${}^{48}\mathrm{Ti}$ is investigated by using proton- and $\alpha$-nucleus elastic scattering at a few to several hundred MeV, which offers different sensitivity to the region of the nuclear density profiles.

Method: Four types of density distributions, the $jj$-coupling shell model and three cluster model configurations, are generated in a single scheme by the antisymmetrized quasicluster model (AQCM). The angular distribution of the proton- and $\alpha \text{−}{}^{48}\mathrm{Ti}$ elastic scattering cross sections are obtained with a reliable high-energy reaction theory, the Glauber model.

Results: The $jj$-coupling shell model configuration is found to best reproduce the proton-nucleus elastic scattering cross section. On the other hand, the trace of the $\alpha$ cluster structure in the tail region of the wave function is embedded in the $\alpha$-nucleus elastic scattering cross section.

Conclusions: Our results suggest that the structure of the nucleus changes as a function of distance from the center, from the $jj$-coupling shell model structure in the surface region to the $\alpha +{}^{44}\mathrm{Ca}$ cluster structure in the tail region. This picture is consistent with the finding of the $\alpha$ knockout reaction on ${}^{48}\mathrm{Ti}$.

Background: The recent discovery and spectroscopic measurements of ${}^{27}\mathrm{O}$ and ${}^{28}\mathrm{O}$ suggests the disappearance of the $N=20$ shell structure in these neutron-rich oxygen isotopes.

Purpose: We measured one- and two-proton removal cross sections from ${}^{27}\mathrm{F}$ and ${}^{29}\mathrm{Ne}$, respectively, extracting spectroscopic factors and comparing them to shell model overlap functions coupled with eikonal reaction model calculations.

Method: The invariant mass technique was used to reconstruct the two-body (${}^{24}\mathrm{O}+n$) and three-body (${}^{24}\mathrm{O}+2n$) decay energies from knockout reactions of ${}^{27}\mathrm{F}$ (106.2 MeV/u) and ${}^{29}\mathrm{Ne}$ (112.8 MeV/u) beams impinging on a ${}^9\mathrm{Be}$ target.

Results: The one-proton removal from ${}^{27}\mathrm{F}$ strongly populated the ground state of ${}^{26}\mathrm{O}$ and the extracted cross section of $3.4_{-1.5}^{+0.3}$ mb agrees with eikonal model calculations that are normalized by the shell model spectroscopic factors and account for the systematic reduction factor observed for single nucleon removal reactions within the models used. For the two-proton removal reaction from ${}^{29}\mathrm{Ne}$ an upper limit of 0.08 mb was extracted for populating states in ${}^{27}\mathrm{O}$ decaying though the ground state of ${}^{26}\mathrm{O}$.

Conclusions: The measured upper limit for the population of the ground state of ${}^{26}\mathrm{O}$ in the two-proton removal reaction from ${}^{29}\mathrm{Ne}$ indicates a significant difference in the underlying nuclear structure of ${}^{27}\mathrm{F}$ and ${}^{29}\mathrm{Ne}$.

Heavy-flavor hadrons produced in ultrarelativistic heavy-ion collisions are a sensitive probe for studying hadronization mechanisms of the quark-gluon-plasma. In this paper, we survey how different transport models for the simulation of heavy-quark diffusion through a quark-gluon plasma in heavy-ion collisions implement hadronization and how this affects final state observables. Utilizing the same input charm-quark distribution in all models at the hadronization transition, we find that the transverse-momentum dependence of the nuclear modification factor of various charm hadron species has significant sensitivity to the hadronization scheme. In addition, the charm-hadron elliptic flow exhibits a nontrivial dependence on the elliptic flow of the hadronizing partonic medium.

We have measured the isospin mixing of the $I^{\pi }=1/2^{+}, E_x=2.599$ MeV state in nearly doubly magic ${}^{47}\mathrm{Ca}$ with the isobaric analog $1/2^{+}$ state of ${}^{47}\mathrm{K}$. Using the TRIUMF atom trap for $\beta$ decay, we have measured a nonzero asymmetry of the progeny ${}^{47}\mathrm{Ca}$ with respect to the initial ${}^{47}\mathrm{K}$ spin polarization, which together with the $\beta$ asymmetry implies a nonzero ratio of Fermi to Gamow-Teller matrix elements $y=0.098\pm 0.037$ for the $1/2^{+}\to 1/2^{+}$ transition. Interpreting $y$ as mixing between this state and the isobaric analog state implies a Coulomb matrix element magnitude $101\pm 37$ keV. This relatively large matrix element supports a model from the literature of analog-antianalog isospin mixing, which predicts large matrix elements in cases involving excess neutrons over protons occupying more than one major shell. The result supports pursuing a search for time-reversal odd, parity-even, isovector interactions using a correlation in ${}^{47}\mathrm{K}\beta$ decay.

The influences of deformation parameters $\beta$ and $\gamma$ on the wobbling motion have been investigated in the framework of particle rotor model taking the valence nucleon $h_{11/2}$ and $i_{13/2}$ combined with a triaxial core as examples. Comprehensive examinations have been carried out to assess the influence of $\beta$ and $\gamma$ on the wobbling frequencies, electromagnetic transition probabilities, and angular momentum geometries. It is demonstrated that larger $\beta$ and smaller $\gamma$ favors the formation of transverse wobbling. In addition, a smaller $\beta$ leads to a smaller transverse wobbling energy, while a larger longitudinal wobbling energy. These behaviors can be well explained by the harmonic frozen alignment approximation method.

Temperature-dependent photon strength function (PSF) models, along with the widely accepted temperature-independent Brink-Axel Lorentzian model, are investigated in their application to determine the properties of the giant dipole resonance (GDR) built on the excited states of nuclei up to a temperature $\approx 1.5$ MeV. Three temperature-dependent models, namely, the simple modified Lorentzian model, the hybrid model by Goriely, and the generalized Lorentzian model of Kopecky and Uhl, are studied. The statistical model calculations with all PSF models reproduce the high-energy ($E_{\gamma }\approx 5$–25 MeV) $\gamma$-ray spectra originating from the decay of ${}^{62}\mathrm{Zn}$ and ${}^{201}\mathrm{Tl}$ compound nuclei reasonably well, and put forward approximately the same peak energy and strength of the gdr. Nevertheless, at a given temperature, significant variation is observed in the predicted GDR width, which may influence the theoretical models used to calculate the GDR width.

Effects of the center-of-mass (CM) correction together with the nucleon electromagnetic form factors on the nuclear charge radius are systematically studied with a relativistic Hartree-Bogoliubov model. Both one- and two-body parts of the CM correction are taken into account. It is found that the one- and two-body CM corrections, and the spin-orbit effect originating from the nucleon anomalous magnetic moments, are all of the same order in magnitude, and that they give sizable impacts on the charge radius from light to heavy nuclei.

The nuclear symmetry energy plays an important role in the structure of finite nuclei as well as in the bulk properties of neutron stars. However, its values at high densities are completely uncertain and the corresponding experimental data have a large error. One possibility to determine or at least estimate the values at high densities is with the help of neutron star observations. Recently, observations of gravitational waves from merging processes of binary neutron star systems provided useful information on both their radius and tidal deformability, quantities directly related to the symmetry energy. In this work, an attempt is made in this direction, namely to see how recent observations can help to constrain the structure of finite nuclei. In particular, in the present study we parametrize the equation of state which describes the asymmetric and symmetric nuclear mater with the help of the parameter $\eta ={\left(K_0{L}^2\right)}^{1/3}$, where $K_0$ is the incompressibility and $L$ the slope parameter. The parameter $\eta$ is a regulator of the stiffness of the equation of state. We expect that the values of $\eta$ affect both the properties of finite nuclei as well as of neutron stars (where the role of the isovector interaction plays important role). It is natural to expect that constraints via the parameter $\eta$ on finite nuclei will imply constraints on the neutron star properties and vice versa. In view of the above statements we propose a simple but self-consistent method to examine simultaneously the effects of the parameter $\eta$ on the properties of finite nuclei and neutron stars. We found constraints on the latter systems via combination of the recent experiments (PREX-2) and observational data found by the detectors LIGO and Virgo.

Employing the nonlinear Walecka model we investigate the characteristics of nuclear matter under the influence of a background magnetic field at a finite temperature and baryon chemical potential. In the presence of the magnetic field the spinodal lines and the critical endpoint (CEP) undergo changes in the $T\text{−}{\mu }_B$ plane. The squared speed of sound exhibits anisotropic behavior, dividing into parallel and perpendicular components. Additionally, the presence of a magnetic field induces anisotropy in the isothermal compressibility. It is found that the parallel component is smaller than the perpendicular one for all values of temperature, chemical potential, and magnetic field, indicating that the equation of state is stiffer along the magnetic-field direction.

We compute the anisotropic electrical conductivity tensor of the inner crust of a compact star at nonzero temperature by extending a previous work on the conductivity of the outer crust. The physical scenarios, where such crust is formed, involve protoneutron stars born in supernova explosions, binary neutron star mergers, and accreting neutron stars. The temperature-density range studied covers the transition from a semidegenerate to a highly degenerate electron gas and assumes that the nuclei form a liquid, i.e., the temperature is above the melting temperature of the lattice of nuclei. The electronic transition probabilities include (i) the screening of electron-ion interaction in the hard-thermal-loop approximation for the QED plasma, (ii) the correlations of the ionic component in a one-component plasma, and (iii) finite nuclear size effects. The conductivity tensor is obtained from the Boltzmann kinetic equation in relaxation time approximation accounting for the anisotropy introduced by a magnetic field. The sensitivity of the results towards the matter composition of the inner crust is explored by using several compositions of the inner crust, which were obtained using different nuclear interactions and methods of solving the many-body problem. The standard deviations of relaxation time and components of the conductivity tensor from the average are below $\le 25\%$ except close to crust-core transition, where nonspherical nuclear structures are expected. Our results can be used in dissipative magnetohydrodynamics simulations of warm compact stars.