We consider momentum broadening and energy loss of high-momentum partons in a hot non-Abelian plasma due to collisions. We solve the coupled system of Wong-Yang-Mills equations on a lattice in real time, including binary hard elastic collisions among the partons. The collision kernel is constructed such that the total collisional energy loss and momentum broadening are lattice-spacing independent. We find that the transport coefficient $\widehat{q}$ corresponding to transverse momentum broadening receives sizable contributions from a power-law tail in the $p_{\perp }$ distribution of high-momentum partons. We establish the scaling of $\widehat{q}$ and of $\mathit{dE}/\mathit{dx}$ with density, temperature, and energy in the weak-coupling regime. We also estimate the nuclear modification factor $R_{\mathit{AA}}$ due to elastic energy loss of a jet in a classical Yang-Mills field.

Within both dynamical and thermodynamical approaches using the equation of state for neutron-rich nuclear matter constrained by the recent isospin diffusion data from heavy-ion reactions in the same subsaturation density range as the neutron star crust, the density and pressure at the inner edge separating the liquid core from the solid crust of neutron stars are determined to be $0.040\hspace{0.5em}{\mathrm{fm}}^{-3}⩽{\rho }_t⩽0.065\hspace{0.5em}{\mathrm{fm}}^{-3}$ and 0.01 MeV/${\mathrm{fm}}^3⩽P_t⩽0.26$ MeV/${\mathrm{fm}}^3$, respectively. These together with the observed minimum crustal fraction of the total moment of inertia allow us to set a new limit for the radius of the Vela pulsar significantly different from the previous estimate. It is further shown that the widely used parabolic approximation to the equation of state of asymmetric nuclear matter leads systematically to significantly higher core-crust transition densities and pressures, especially with stiffer symmetry energy functionals.

We study the structure of low-lying states of ${}^{13}\mathrm{C}$ with a microscopic cluster model. In addition to the $3\alpha \text{−}n$ model space, the breaking effect of one of the $\alpha$ clusters due to the spin-orbit interaction is also taken into account. The isoscalar $E0$ transition probabilities from the ground $1/2^{-}$ state to the excited ones are discussed associated with the cluster structure of these states.

We have calculated the strength distributions of the isoscalar giant monopole resonance (ISGMR) in the even-$A$ tin isotopes ($A=112\text{−}124$) that were recently measured in inelastic $\alpha$ scattering. The calculations were performed within two microscopic models: the quasiparticle random phase approximation (QRPA) and the quasiparticle time blocking approximation (QTBA), which is an extension of the QRPA including quasiparticle-phonon coupling. We used a self-consistent calculational scheme based on the Hartree-Fock$+$Bardeen-Cooper-Schrieffer approximation. Within the RPA the self-consistency is full. The single-particle continuum is also exactly included at the RPA level. The self-consistent mean field and the effective interaction are derived from the Skyrme energy functional. In the calculations, two Skyrme force parametrizations were used: T5 with a comparatively low value of the incompressibility modulus of infinite nuclear matter ($K_{\infty }=202$ MeV) and T6 with $K_{\infty }=236$ MeV. The T5 parametrization gives theoretical results for tin isotopes in good agreement with the experimental data including the resonance widths. The results of the ISGMR calculations in ${}^{90}\mathrm{Zr}$, ${}^{144}\mathrm{Sm}$, and ${}^{208}\mathrm{Pb}$ performed with these Skyrme forces are discussed and compared with the experiment.

We explore the abundance of light clusters in asymmetric nuclear matter at subsaturation density. With increasing density, binding energies and wave functions are modified due to medium effects. The method of Albergo, Costa, Costanzo, and Rubbino (ACCR) for determining the temperature and free nucleon density of a disassembling hot nuclear source from fragment yields is modified to include, in addition to Coulomb effects and flow, also effects of medium modifications of cluster properties, which become of importance when the nuclear matter density is above ${10}^{-3}\hspace{0.5em}{\mathrm{fm}}^{-3}$. We show how the analysis of cluster yields, to infer temperature and nucleon densities, is modified if the shifts in binding energies of in medium clusters are included. Although, at low densities, the temperature calculated from given yields changes only modestly if medium effects are taken into account, larger discrepancies are observed when the nucleon densities are determined from measured yields.

Above-barrier cross sections of fission and $\alpha$-active heavy reaction products were measured for the reactions of ${}^{10,11}\mathrm{B}$ with ${}^{209}\mathrm{Bi}$. Systematic analysis showed that the fission originates almost exclusively from complete fusion (CF). Existing measurements of above-barrier fusion products for the ${}^{30}\mathrm{Si}+{}^{186}\mathrm{W}$ reaction, assumed to proceed exclusively through CF, were extrapolated to the current systems using statistical model calculations. This extrapolation showed that the heavy reaction products from the ${}^{10,11}\mathrm{B}+{}^{209}\mathrm{Bi}$ reactions include substantial components from incomplete fusion as well as from CF. Compared with fusion calculations without breakup, the CF cross sections are suppressed by 15% for ${}^{10}\mathrm{B}$ and 7% for ${}^{11}\mathrm{B}$. A consistent and systematic variation of the suppression of CF for reactions of the weakly bound nuclei ${}^{6,7}\mathrm{Li}$, ${}^9\mathrm{Be}$, and ${}^{10,11}\mathrm{B}$ on targets of ${}^{208}\mathrm{Pb}$ and ${}^{209}\mathrm{Bi}$ is found as a function of the breakup threshold energy.

We present a fully relativistic and gauge-invariant framework for calculating the cross sections of dilepton production in nucleon-nucleon ($\mathit{NN}$) collisions that is based on the meson-exchange approximation for the $\mathit{NN}$-scattering amplitudes. Predictions of our model are compared with those of other covariant models that have been used earlier to describe this reaction. Our results are also compared with those of the semiclassical models that are employed to get the input elementary cross sections in the transport model calculations of the dilepton production in nucleus-nucleus collisions. It is found that cross sections obtained within the semiclassical and quantum mechanical models differ noticeably from each other.

We perform calculations for the neutron skin of nuclei and its contribution to atomic parity nonconservation (PNC) in many isotopes of Cs, Ba, Sm, Dy, Yb, Tl, Pb, Bi, Fr, and Ra. Three problems are addressed: (i) neutron-skin-induced errors to single-isotope PNC, (ii) the possibility of measuring neutron skin using atomic PNC, and (iii) neutron-skin-induced errors for ratios of PNC effects in different isotopes. In the latter case the correlations in the neutron skin values for different isotopes lead to cancellations of the errors; this makes the isotopic ratio method a competitive tool in a search for new physics beyond the standard model.

Corrections to the superallowed $\beta$ decay matrix elements are evaluated in perturbation theory using the notion of the isovector monopole resonance. The calculation avoids the separation into different contributions and thus presents a consistent, systematic, and more transparent approach. Explicit expressions for ${\delta }_c$ as a function of the mass number$A$ are given.

We study the collective density modes that can affect neutron-star thermodynamics in the baryonic density range between nuclear saturation (${\rho }_0$) and $3{\rho }_0$. In this region, the expected constituents of neutron-star matter are mainly neutrons, protons, and electrons ($\mathit{npe}$ matter), under the constraint of $\beta$ equilibrium. The elementary excitations of this $\mathit{npe}$ medium are studied in the random-phase approximation framework. We emphasize the effect of Coulomb interaction, in particular the electron screening of the proton plasmon mode. For the treatment of the nuclear interaction, we compare two modern Skyrme forces and a microscopic approach. The importance of the nucleon effective mass is observed.

The spectral properties of a tractable collective model Hamiltonian are studied. The potential energy is truncated up to quartic terms in the quadrupole deformation variables, incorporating vibrational, $\gamma$-independent rotational, and axially deformed rotational structures. These physically significant limits are analysed in detail and confronted with well-established approximation schemes. Furthermore, transitional Hamiltonians in between the limits are presented and discussed. All results are obtained within a recently presented Cartan-Weyl based framework to calculate $\mathrm{SU}(1,1)\times \mathrm{SO}(5)$ embedded quadrupole collective observables.

We survey odd-even nuclear binding energy staggering using density functional theory with several treatments of the pairing interaction including the BCS, Hartree-Fock-Bogoliubov, and the Hartree-Fock-Bogoliubov with the Lipkin-Nogami approximation. We calculate the second difference of binding energies and compare the results with 443 measured neutron energy differences in isotope chains and 418 measured proton energy differences in isotone chains. The particle-hole part of the energy functional is taken as the SLy4 Skyrme parametrization, and the pairing part of the functional is based on a contact interaction with possible density dependence. An important feature of the data, reproduced by the theory, is the sharp gap quenching at magic numbers. With the strength of the interaction as a free parameter, the theory can reproduce the data to an rms accuracy of about 0.25 MeV. This is slightly better than a single-parameter phenomenological description but slightly poorer than the usual two-parameter phenomenological form $c/A^{\alpha }$. The following conclusions can be made about the performance of common parametrization of the pairing interaction: (i) there is a weak preference for a surface-peaked neutron-neutron pairing, which might be attributable to many-body effects, (ii) a larger strength is required in the proton pairing channel than in the neutron pairing channel, and (iii) pairing strengths adjusted to the well-known spherical isotope chains are too weak to give a good overall fit to the mass differences.

Relative and absolute $E0$ transition strengths $[{\rho }^2(E0)]$ on the transitional path between the X(5) solution and the rigid rotor limit have been evaluated within the framework of the confined $\beta$ soft (CBS) rotor model. Relative $E0$ transition strengths between the $\beta$-vibrational band and the ground state band decrease with increasing angular momentum for a given potential stiffness. Absolute $E0$ transition strengths drop with increasing potential stiffness toward zero in the rigid rotor limit. Interband $E0\text{−}E2$ correlation observables are examined to estimate ${\rho }^2(E0)$ as a function of the $R_{4/2}$ ratio.

Assuming a schematic form of the nucleon effective mass as a function of nuclear excitation energy and mass, we provide a simple explanation for understanding the experimentally observed mass dependence of the nuclear caloric curve. It is observed that the excitation energy at which the caloric curve enters into a plateau region could be sensitive to the nuclear mass evolution of the effective nucleon mass.

Excited states in ${}^{256}\mathrm{Rf}$ were populated via the ${}^{208}\mathrm{Pb}({}^{50}\mathrm{Ti},2n)$ fusion–evaporation reaction. Delayed $\gamma$-ray and electron decay spectroscopy was performed and three isomeric states in ${}^{256}\mathrm{Rf}$ have been identified. A fourth low-energy nonyrast state was identified from the $\gamma$-ray decay of one of the higher lying isomers. The states are interpreted as multi-quasiparticle excitations.

The Bardeen/Cooper/Schrieffer–Bose-Einstein condensation (BCS-BEC) crossover and phase diagram for asymmetric nuclear superfluid with pairings in isospin $I=0$ and $I=1$ channels are investigated at the mean-field level by using a density-dependent nucleon-nucleon potential. Induced by the in-medium nucleon mass and density-dependent coupling constants, neutron-proton Cooper pairs could be in BEC state at sufficiently low density, but there is no chance for the BEC formation of neutron-neutron and proton-proton pairs at any density and asymmetry. We calculate the phase diagram in asymmetry-temperature plane for weakly interacting nuclear superfluid and find that including the $I=1$ channel changes significantly the phase structure at low temperature. There appears a new phase with both $I=0$ and $I=1$ pairings at low temperature and low asymmetry, and the gapless state in any phase with $I=1$ pairing is washed out and all excited nucleons are fully gapped.

Application of the preformed clusters based dynamical cluster-decay model (DCM) is made to the recent data on decay of the compound systems ${}^{118,122}\mathrm{Ba}{}^{*}$ at a relatively low bombarding energy of 5.5 MeV/$A$. The same model has been applied earlier to the intermediate mass fragment (IMF) data of ${}^{116}\mathrm{Ba}{}^{*}$, observed at medium and higher incident energies. For the heavier ${}^{118,122}\mathrm{Ba}{}^{*}$ systems, however, a complete mass fragmentation spectrum is observed experimentally. Except for a small narrow region of heavier mass fragments ($8⩽Z_L⩽15$), the DCM gives an overall reasonable description of the observed data on both the intermediate mass fragments and the fusion-fission cross-sections, whereas the statistical model calculations based on BUSCO and GEMINI codes describe the intermediate mass fragment data and the heavier mass fragment and fusion-fission data, respectively. Within the DCM (with preformation factor $P_0=1$), the possibility of non-compound-nucleus decay contributing to the region $8⩽Z_L⩽15$ of heavier mass fragments is also explored. All three models use the maximum angular momentum ${\ell }_{\max }$ as a fitting parameter, which in the DCM is fixed via a neck-length parameter for the penetrability $P\to 1$.

Neutron and proton evaporation spectra from the ${}^6\mathrm{Li}+{}^{55}\mathrm{Mn}$ and $d+{}^{59}\mathrm{Co}$ reactions have been analyzed with the Hauser-Feshbach approach using different input models for nuclear level densities of ${}^{60}\mathrm{Ni}$ and ${}^{60}\mathrm{Co}$ nuclei. It has been found that models with a Fermi-gas like temperature dependence fail to reproduce particle spectra from both reactions simultaneously. We obtained the surprising result that the only way to describe our data is to assume the independence of the nuclear temperature on the excitation energy up to about the 20 MeV energy range.

Internal conversion coefficients have been measured for transitions following the decay of the 32 μs isomer in the neutron-deficient isotope ${}^{189}\mathrm{Pb}$. The main branch at 337 keV to the $25/2^{+}$ excited state is shown to be of $E3$ multipolarity with a strength of about 24 W.u. This, together with multipolarity assignments to other branches, leads to a spin and parity assignment of $K^{\pi }=31/2^{-}$ for the 2435-keV state. This also defines that state as the isomer, rather than the lifetime being due to feeding from a higher lying $33/2^{+}$ isomeric state as had been proposed previously. The isomer is suggested to arise from the partially aligned coupling of the ${11}^{-}$ two-proton configuration with the $i_{13/2}$ neutron hole. The low-lying nature of the ${31/2}^{-}$ multiplet member is attributed to the change in quasiparticle character of the $i_{13/2}$ neutron configuration as the neutron shell is depleted.

The effects of the variation of the dimensionless strong interaction parameter $X_q=m_q/{\Lambda }_{\mathrm{QCD}}\hspace{0.5em}$ ($m_q$ is the quark mass, ${\Lambda }_{\mathrm{QCD}}$ is the QCD scale) are enhanced about $1.5\times {10}^5$ times in the 7.6 eV “nuclear clock” transition between the ground and first excited states in the ${}^{229}\mathrm{Th}$ nucleus and about $1\times {10}^8$ times in the relative shift of the 0.1 eV compound resonance in ${}^{150}\mathrm{Sm}$. The best terrestrial limit on the temporal variation of the fundamental constants, $|\delta X_q/X_q|<4\times {10}^{-9}$ at 1.8 billion years ago ($|{\stackrel{·}{X}}_q/X_q|<2.2\times {10}^{-18}{\mathrm{y}}^{-1}$), is obtained from the shift of this Sm resonance derived from the Oklo natural nuclear reactor data. The results for ${}^{229}\mathrm{Th}$ and ${}^{150}\mathrm{Sm}$ are obtained by extrapolation from light nuclei where the many-body calculations can be performed more accurately. The errors produced by such extrapolation may be smaller than the errors of direct calculations in heavy nuclei. The extrapolation results are compared with the “direct” estimates obtained using the Walecka model. A number of numerical relations needed for the calculations of the variation effects in nuclear physics and atomic spectroscopy have been obtained: for the nuclear binding energy $\delta E/E\approx -1.45\hspace{0.5em}\delta m_q/m_q$, for the spin-orbit intervals $\delta E_{\mathit{so}}/E_{\mathit{so}}\approx -0.22\hspace{0.5em}\delta m_q/m_q$, for the nuclear radius $\delta r/r\approx 0.3\hspace{0.5em}\delta m_q/m_q$ (in units of ${\Lambda }_{\mathrm{QCD}}$); for the shifts of nuclear resonances and weakly bound energy levels $\delta E_r\approx 10\hspace{0.5em}\delta X_q/X_q$ MeV.