Peripheral collisions of ${}^{40}\mathrm{Ca}$ and ${}^{48}\mathrm{Ca}$ projectiles at 32 MeV/nucleon on ${}^{112}\mathrm{Sn}$ and ${}^{124}\mathrm{Sn}$ targets were studied in this work. The fragments of the projectile-like source (quasiprojectile) were collected with a charged-particle multidetector array. The average value of the neutron-to-proton ratio $N/Z$ of the quasiprojectiles formed in the reactions was determined with two approaches. The first is a direct reconstruction approach using isotopically resolved fragments and is hindered by undetected neutrons leading to lower $N/Z$ values. The second approach, based on the assumption of early fragment formation, employs yield ratios of fragment isobars and is not hindered by undetected neutrons. Using this approach, the amount of $N/Z$ mixing that occurred in the quasiprojectiles (compared to a fully $N/Z$ equilibrated system) was found to be approximately $53\%$. The experimental results were compared with model calculations. First, the phenomenological DIT (deep inelastic transfer) model was used, followed by the statistical multifragmentation model (SMM). The results of these calculations are in close agreement with the data and indicate that the mean number of undetected neutrons increases with the $N/Z$ of the composite system, accounting for the difference observed between the two approaches of quasiprojectile $N/Z$ determination. Second, the microscopic transport model IBUU (isospin-dependent Boltzmann-Uehling-Uhlenbeck) was employed, providing preliminary results in reasonable agreement with the data. The determination of the degree of $N/Z$ equilibration employing the present fragment yield ratio approach may provide a valuable probe to study the isospin part of the nuclear equation of state in conjunction with detailed microscopic models of the collisions in the Fermi energy regime.

In the framework of an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, for the central ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ reaction at an incident beam energy of $400$ MeV/nucleon, the effect of nuclear symmetry potential at supra-saturation densities on the preequilibrium clusters emission is studied. It is found that for the positive symmetry potential at supra-saturation densities the neutron-to-proton ratio of lighter clusters with mass number $A⩽3$ [$(n/p){}_{A⩽3}$] is larger than that of the heavier clusters with mass number $A>3$ [$(n/p){}_{A>3}$], whereas for the negative symmetry potential at supra-saturation densities the $(n/p){}_{A⩽3}$ is smaller than the $(n/p){}_{A>3}$. This may be considered as a probe of the negative symmetry potential at supra-saturation densities.

We investigate the $\Lambda (1520,3/2^{-})\equiv {\Lambda }^{*}$ photoproduction off the proton target beyond the resonance region within a model including the Regge contributions, the tree-level diagrams with the nucleon and the certain resonance intermediate states, and one contact term. The Reggeized propagators for the $K$ and $K^{*}$ exchanges in the $t$ channel are employed in a gauge-invariant manner. We compute the angular and energy dependences of the cross section and some polarization observables, such as the photon-beam asymmetry and the polarization-transfer coefficients. Our results qualitatively agree with the current experimental data. We find that the Regge contributions are necessary to explain the high-energy data beyond $E_{\gamma }\approx 4$ GeV, especially for the angular dependences in the forward region. On the contrary, the polarization observables are insensitive to the Regge contributions due to the contact-term dominance, which is a consequence of gauge invariance. We also calculate the $K^{-}$-angle distribution function in the Gottfried-Jackson frame, using the polarization-transfer coefficients in the $z$ direction. We find that it owns a complicated angle and energy dependences in the forward $K^{+}$ scattering region.

The LEPS Collaboration has recently reported a measurement of the $\gamma n\to K^{+}{\Sigma }^{*-}(1385)$ reaction using a linearly polarized photon beam around the resonance region. The observed beam asymmetry is sizably negative at $E_{\gamma }=1.8$–$2.4$ GeV, in contrast to the presented theoretical prediction. In this paper, we calculate this process using the framework of the effective Lagrangian approach. By including a newly proposed $\Sigma (J^P={\frac{1}{2}}^{-})$ state with a mass around 1380 MeV, the experimental data for both $\gamma n$ and $\gamma p$ experiments can be well reproduced. It is found that the $\Sigma ({\frac{1}{2}}^{-})$ and/or the contact term may play an important role and may deserve further investigation.

I study $K^{+}d$ scattering at low energies using optical potential. My optical potential consists of the first- and second-order terms. The total, integrated elastic, and elastic differential cross sections at incident kaon momenta below $800$ MeV/$c$ are calculated using my optical potential. I found that my results are consistent with the Faddeev calculation as well as the data and especially that the second-order optical potential is essential for reproducing them at low energies. I also discuss the multiple scattering effects in this process.

We extend the study of a $J^P=2^{+},I=3/2$, $\pi \Lambda N$ quasibound state [Phys. Rev. D 78, 014013 (2008)] by solving nonrelativistic Faddeev equations, using ${}^3{S}_1-{}^3{D}_1$, $\Lambda N-\Sigma N$ coupled channels chiral quark model local interactions, and $\pi N$ and coupled $\pi \Lambda -\pi \Sigma$ separable interactions fitted to the position and decay parameters of the $\Delta (1232)$ and $\Sigma (1385)$ resonances, respectively. The results exhibit a strong sensitivity to the $p$-wave pion-hyperon interaction, with a $\pi \Lambda N$ quasibound state persisting over a wide range of acceptable parametrizations.

High-spin states of ${}^{106}\mathrm{Ag}$ were populated via the fusion-evaporation reaction ${}^{100}\mathrm{Mo}$ (${}^{11}\mathrm{B}$,$5n$)${}^{106}\mathrm{Ag}$ at a beam energy of $60$ MeV. A rich level scheme with six band structures has been established. A high-$K$ negative-parity band has been identified and assigned to the $\pi g_{9/2}\otimes \nu [h_{11/2}(g_{7/2}/d_{5/2}){}^2$] configuration. The positive parity $△I=1$ band, built on the ${12}^{+}$ state, is discussed in terms of the magnetic rotation model. The systematic study of similar bands in the $A~110$ mass region indicates that the magnetic rotation phenomenon has, as lower boundary, the Ag isotopes at $Z=47$.

The hydrokinetic approach that incorporates hydrodynamic expansion of the systems formed in $A+A$ collisions and their dynamical decoupling is applied to restore the initial conditions and space-time picture of the matter evolution in central $\mathrm{Au}+\mathrm{Au}$ collisions at the top Relativistic Heavy Ion Collider energy. The analysis is based on the detailed reproduction of the pion and kaon momentum spectra and femtoscopic data in whole interval of the transverse momenta studied by both the STAR and the PHENIX collaborations. The fitting procedure utilizes the two parameters: the maximal energy density at supposed thermalization time $1$ fm$/c$ and the strength of the prethermal flows developed to this time. The quark-gluon plasma and hadronic gas is supposed to be in complete local equilibrium above the chemical freeze-out temperature $T_{\mathrm{ch}}=165$ MeV with the equation of states (EoS) at high temperatures as in the lattice QCD. Below $T_{\mathrm{ch}}$ the EoS in the expanding and gradually decoupling fluid depends on the composition of the hadron-resonance gas at each space-time point and accounts for decays of resonances into the nonequilibrated medium. A good description of the pion and kaon transverse momentum spectra and interferometry radii is reached at both used initial energy density profiles motivated by the Glauber and color glass condensate models, however, at different initial energy densities. The discussion as for the approximate pion and kaon $m_T$ scaling for the interferometry radii is based on a comparison of the emission functions for these particles.

In this paper, we demonstrate the use of physical models to evaluate the production of ${}^{39}\mathrm{Ar}$ and ${}^{40}\mathrm{Ar}$ underground. Considering both cosmogenic ${}^{39}\mathrm{Ar}$ production and radiogenic ${}^{40}\mathrm{Ar}$ production in situ and from external sources, we can derive the ratio of ${}^{39}\mathrm{Ar}$ to ${}^{40}\mathrm{Ar}$ in underground sources. We show for the first time that the ${}^{39}\mathrm{Ar}$ production underground is dominated by stopping negative muon capture on ${}^{39}\mathrm{K}$ and ($\alpha ,n)$ induced subsequent ${}^{39}\mathrm{K}$($n$,$p$)${}^{39}\mathrm{Ar}$ reactions. The production of ${}^{39}\mathrm{Ar}$ is shown as a function of depth. We demonstrate that argon depleted in ${}^{39}\mathrm{Ar}$ can be obtained only if the depth of the underground resources is greater than $500$ m.w.e. below the surface. Stopping negative muon capture on ${}^{39}\mathrm{K}$ dominates over radiogenic production at depths of less than $2000$ m.w.e., and that production by muon-induced neutrons is subdominant at any depth. The depletion factor depends strongly on both radioactivity level and potassium content in the rock. We measure the radioactivity concentration and potassium concentration in the rock for a potential site of an underground argon source in South Dakota. Depending on the probability of ${}^{39}\mathrm{Ar}$ and ${}^{40}\mathrm{Ar}$ produced underground being dissolved in the water, the upper limit of the concentration of ${}^{39}\mathrm{Ar}$ in the underground water at this site is estimated to be in a range of a factor of $1.6$ to $155$ less than the ${}^{39}\mathrm{Ar}$ concentration in the atmosphere. The calculation tools presented in this paper are also critical to the dating method with ${}^{39}\mathrm{Ar}$.

The high-spin structure of the $Z=77$ nucleus ${}^{187}\mathrm{Ir}$ has been studied using the fusion-evaporation reaction ${}^{186}\mathrm{W}$(${}^7\mathrm{Li}$$6n$) at a beam energy of $59$ MeV. The excitation scheme of this nucleus has been extended by more than $110$ new states, including extensions of all previously established rotational bands. The band crossing region of the $h_{9/2}$ negative-parity yrast band has been revised and new intrinsic high-$K$ states have been identified. In particular, a $29/2^{-}$ isomeric state [$T_{1/2}=1.8(5)$$\mu$s] at an excitation energy of $2487$ keV has been observed for the first time, and on top of it, a rich level scheme reaching up to spin ($59/2^{-}$) and excitation energies around $7$ MeV has been established.

Yrast states up to $(6^{+})$ in the neutron-rich ${}^{40}\mathrm{S}$ nucleus have been studied using binary grazing reactions produced by the interaction of a $215$ MeV beam of ${}^{36}\mathrm{S}$ ions with a thin ${}^{208}\mathrm{Pb}$ target. The novel experimental setup that combines the large acceptance magnetic spectrometer, PRISMA, and the high-efficiency $\gamma$-ray detection array, CLARA, was used. A new $\gamma$-ray transition at an energy of $1572$ keV was observed and tentatively assigned to the $(6^{+})\to (4^{+})$ transition. A comparison of experimental observations and the results of large-scale $0\hslash \omega$ $\mathit{sd}-\mathit{pf}$ shell-model calculations indicates that one- and two-proton excitations from the $2s_{1/2}$ to the $1d_{3/2}$ orbitals play an important role in reproducing the ${}^{40}\mathrm{S}$ yrast level structure and the published $B(E2;0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+})$ value. The structure of the yrast states of the even-$A$ isotopes of sulfur is interpreted in terms of the configurations of valence protons and neutrons within the context of large-scale $0\hslash \omega$ $\mathit{sd}-\mathit{pf}$ shell-model calculations.

We present a calculation of the $\gamma d\to K^{+}{K}^{-}np$ reaction with the aim of seeing whether the experimental peak observed in the $K^{+}n$ invariant mass around $1526$ MeV, from where evidence for the existence of the ${\Theta }^{+}$ has been claimed, can be obtained without this resonance as a consequence of the particular dynamics of the process and the cuts applied in the experimental setup. We find that a combination of facts leads indeed to a peak around $1530$ MeV for the invariant mass of $K^{+}n$ without the need to invoke any new resonance around this energy. This, together with statistical fluctuations that we prove to be large with the statistics of the experiment, is likely to produce the narrower peak observed there.

We study the generation of the directed flow in the hydrodynamic expansion of hot matter formed in ultrarelativistic heavy-ion collisions at $\sqrt{s}=200$ GeV. The experimentally observed negative-directed flow in a wide range of central pseudorapidities is reproduced, assuming that the fireball is tilted away from the collision axis. The tilt of the source is consistent with a preferential emission in the forward-backward hemisphere from forward-backward participating nucleons. The model reproduces the experimentally observed scaling of the directed flow when going from Au-Au to Cu-Cu systems.

We consider the two-nucleon weak interaction with a pionless effective field theory. Dibaryon fields are introduced to ensure fast convergence of the perturbative expansion. Weak interactions are accounted for with the parity-violating dibaryon-nucleon-nucleon vertices, which contain unknown weak coupling constants. We apply the model to the calculation of a parity-violating observable in the radiative neutron capture on a proton at threshold. Result is obtained up to the linear order of the weak dibaryon-nucleon-nucleon coupling constants. We compare our result to the ones obtained from other approaches, and discuss investigation of the weak interaction in few-body systems.

We study the scaling properties of proton-nucleus total reaction cross sections for stable nuclei and propose an approximate expression in proportion to $Z^{2/3}{\sigma }_{\mathit{pp}}^{\mathrm{total}}+N^{2/3}{\sigma }_{\mathit{pn}}^{\mathrm{total}}$. Based on this expression, we can derive a relation that enables us to predict a total reaction cross section for any stable nucleus within $10\%$ uncertainty at most, using the empirical value of the total reaction cross section of a given nucleus.

The input to the configuration-interaction shell model includes many dozens or hundreds of independent two-body matrix elements. Previous studies have shown that when fitting to experimental low-lying spectra, the greatest sensitivity is to only a few linear combinations of matrix elements. Here we consider interactions drawn from the two-body random ensemble and find that the low-lying spectra are also most sensitive to only a few linear combinations of two-body matrix elements, in a fashion nearly indistinguishable from an interaction empirically fit to data. We find in particular the spectra for both random and empirical interactions are sensitive to similar matrix elements, which we analyze using monopole and contact interactions.

The thermodynamics and critical exponents and amplitudes of high temperature and dense matter near the chiral critical point are studied. The parameterized equation of state matches that calculated with lattice QCD at zero chemical potential and to the known properties of nuclear matter at zero temperature. The extent to which finite size effects wash out the phase separation near the critical point is determined.

We study the structure of the no-core shell model wave functions for ${}^6\mathrm{Li}$ and ${}^{12}\mathrm{C}$ by investigating the ground state and first excited state electron scattering charge form factors. In both nuclei, large particle-hole (ph) amplitudes in the wave functions appear with the opposite sign to that needed to reproduce the shape of the $(e,e^{\prime })$ form factors, the charge radii, and the B(E2) values for the lowest two states. The difference in sign appears to arise mainly from the monopole $\Delta \hslash \omega =2$ matrix elements of the kinetic and potential energy ($T+V$) that transform under the harmonic oscillator SU(3) symmetries as $(\lambda ,\mu )=(2,0)$. These are difficult to determine self-consistently, but they have a strong effect on the structure of the low-lying states and on the giant monopole and quadrupole resonances. The Lee-Suzuki transformation, used to account for the restricted nature of the space in terms of an effective interaction, introduces large higher-order $\Delta \hslash \omega =n,n>2$, ph amplitudes in the wave functions. The latter ph excitations aggravate the disagreement between the experimental and predicted $(e,e^{\prime })$ form factors with increasing model spaces, especially at high momentum transfers. For sufficiently large model spaces, the situation begins to resolve itself for ${}^6\mathrm{Li}$, but the convergence is slow. A prescription to constrain the ph excitations would likely accelerate convergence of the calculations.

We examine how nuclear masses are related to the density dependence of the symmetry energy. Using a macroscopic nuclear model we calculate nuclear masses in a way dependent on the equation of state of asymmetric nuclear matter. We find by comparison with empirical two-proton separation energies that a smaller symmetry energy at subnuclear densities, corresponding to a larger density symmetry coefficient $L$, is favored. This tendency, which is clearly seen for nuclei that are neutron-rich, nondeformed, and light, can be understood from the property of the surface symmetry energy in a compressible liquid-drop picture.