We use properties of doubly magic nuclei, ab initio calculations of low-density neutron matter and of neutron stars to constrain the parameters of the Skyrme energy-density functional. We find all of these properties can be reproduced within a constrained family of Skyrme parameters. The maximum mass of a neutron star is found to be sensitive to the neutron effective mass. A value of $[m_n^{*}/m]\left({\rho }_0\right)=0.60–0.65$ is required to obtain a maximum neutron-star mass of 2.0 to 2.1 solar masses. Using the constrained Skyrme functional with the aforementioned effective mass, the predicted radius for a neutron star of 1.4 solar masses is 12.4(1) km and tidal polarizability is $\mathrm{\Lambda }=423\left(40\right)$.

It is known that the monopole effect in shell-model calculations can influence single-particle states dynamically, resulting in novel shell evolution near the ground state. We show that a monopole-driven competition between different excitation modes can occur in the high-lying, high-spin states in nuclei above ${}^{132}\mathrm{Sn}$. Stimulated by the recent high-spin data, we extend large-scale shell-model calculations with the effective interaction determined in our previous work [Phys. Rev. C 84, 044324 (2011)] to study the heavier $N=82$ isotones ${}^{136}\mathrm{Xe}, {}^{137}\mathrm{Cs}$, and ${}^{138}\mathrm{Ba}$. With inclusion of configurations for neutron core excitation across the $N=82$ shell gap, we treat simultaneously two kinds of excitation modes for the high-spin states, namely, those from multiproton coupling within the valence-proton space and from neutron core excitation to the upper orbits above the $N=82$ shell gap. Based on a good reproduction of the experimental data, we discuss the competition mechanism by analyzing the monopole effect in the effective single-particle energies.

The heaviest $N$ = 127 even-odd isotone ${}^{219}\mathrm{U}$ was produced in a fusion evaporation reaction employing ${}^{40}\mathrm{Ar}$ ions bombarding ${}^{183}\mathrm{W}$ target. Fusion evaporation residues were separated in flight by the gas-filled recoil separator Spectrometer for Heavy Atoms and Nuclear Structure and subsequently identified using a recoil-$\alpha$ correlation method. The $\alpha$-decay properties of ${}^{219}\mathrm{U}$ were measured with improved precision, and two new $\alpha$-decay lines were observed and assigned as the decays from the ground state of ${}^{219}\mathrm{U}$ to the ($5/2^{-}$) and ($3/2^{-}$) states of ${}^{215}\mathrm{Th}$, respectively. The systematics for the $\alpha$ decay of the $N$ = 127 even-odd isotones as well as the low-lying nuclear structure of their $N$ = 125 daughter nuclei are discussed.

The giant resonance region from $10\mathrm{MeV}<E_x<62\mathrm{MeV}$ in ${}^{54}\mathrm{Fe}, {}^{64}\mathrm{Zn}$, and ${}^{68}\mathrm{Zn}$ has been studied with inelastic scattering of 240-MeV $\alpha$ particles at small angles, including $0^{\circ }$. Between 70 and $105\%$ of the expected isoscalar $E0$ strength has been identified below $E_x=40\mathrm{MeV}$ for each of the nuclei. Between 71 and $108\%$ of the $E1$ strength has been identified while $60\%$ of $E2$ strength in ${}^{54}\mathrm{Fe}$ and ${}^{68}\mathrm{Zn}$ and $120\%$ of the strength in ${}^{64}\mathrm{Zn}$ have been identified. The strength distributions for ${}^{54}\mathrm{Fe}$ and ${}^{64,68}\mathrm{Zn}$ are compared with the predictions from HF-RPA calculations with the KDE0v1 Skyrme interaction.

The evolution of spin-orbit splittings of neutron drops along with the neutron number and its connection with the tensor-force strength have been investigated systematically for different external fields in the relativistic Brueckner-Hartree-Fock (RBHF) and relativistic Hartree-Fock (RHF) theories. Based on the RHF functional PKO1, it is found that a good consistency between the RBHF and RHF results for the total energies can be obtained only for those neutron drops whose central densities are close to the saturation density of nuclear matter. Nevertheless, by rescaling the density dependence of the RHF functional, the RBHF total energies of neutron drops in different external fields can be well reproduced. The optimized tensor-force strength $\lambda$ in the RHF theory, which reproduces the microscopic RBHF spin-orbit splittings, is running with the strength of the external fields of neutron drops. This provides an important guide for future determination of tensor forces in nuclear energy density functionals based on microscopic ab initio calculations.

The average prompt-fission-neutron multiplicity $\overline{\nu }$ is of significance in the areas of nuclear theory, nuclear nonproliferation, and nuclear energy. In this work, the surrogate-reaction method has been used for the first time to indirectly determine $\overline{\nu }$ for ${}^{239}\mathrm{Pu}(n,f)$ via ${}^{240}\mathrm{Pu}(\alpha ,{\alpha }^{\prime }f)$ reactions. A ${}^{240}\mathrm{Pu}$ target was bombarded with a beam of 53.9-MeV $\alpha$ particles. Scattered $\alpha$ particles, fission products, and neutrons were measured with the NeutronSTARS detector array. Values of $\overline{\nu }$ were obtained for a continuous range of equivalent incident neutron energies between 0.25 and 26.25 MeV, and the results agree well with direct neutron measurements.

We investigate deuterium-tritium (DT) fusion cross sections in the presence of electromagnetic fields with high intensity and high frequency. With the help of the Kramers-Henneberger (KH) transformation, we show that the corresponding Coulomb barrier penetrability increases significantly due to the depression of the time-averaged potential barrier. As a result, we find that DT fusion cross sections can be enhanced depending effectively on a dimensionless quantity $n_{\mathrm{d}}$, which equals the ratio of the quiver oscillation amplitude to the geometrical touching radius of the deuterium and tritium nuclei. For $n_{\mathrm{d}}=9$, we predict that the fusion cross section is almost five times the value in the absence of electromagnetic fields, which implies that the famous Lawson criterion might be relaxed to some extent.

We construct an equation of state for quantum chromodynamics (QCD) at finite temperature and chemical potentials for baryon number $B$, electric charge $Q$, and strangeness $S$. We use the Taylor expansion method to the fourth power for the chemical potentials. This requires the knowledge of all diagonal and nondiagonal $BQS$ correlators up to fourth order: These results recently became available from lattice QCD simulations, albeit only at a finite lattice spacing $N_t=12$. We smoothly merge these results to the hadron resonance gas as model, to be able to reach temperatures as low as 30 MeV; in the high-temperature regime, we impose a smooth approach to the Stefan-Boltzmann limit. We provide a parametrization for each one of these $BQS$ correlators as functions of the temperature. We then calculate pressure, energy density, entropy density, baryonic, strangeness, and electric charge densities and compare the two cases of strangeness neutrality and ${\mu }_S={\mu }_Q=0$. Finally, we calculate the isentropic trajectories and the speed of sound and compare them in the two cases. Our equation of state can be readily used as an input of hydrodynamical simulations of matter created at the Relativistic Heavy Ion Collider.

Hard probes produced in perturbative processes are excellent probes for the study of the hot and dense QCD matter created in relativistic heavy-ion collisions. Transport theory, allowing for coupling to an evolving medium with fluctuating initial conditions, has become a powerful tool in this endeavor. However, the implementation of the Landau-Pomeranchuk-Migdal (LPM) effect for medium-induced parton bremsstrahlung and pair production poses a challenge to semiclassical transport models based on Boltzmann-type transport equations. In this work, we investigate a possible solution to approximate the LPM effect in a “modified Boltzmann transport” approach, including a prescription for the running coupling constant. By fixing a numerical parameter, this approach quantitatively reproduces the rates of medium-induced parton splitting predicted by the next-to-leading-log solution of the Arnold-Moore-Yaffe equation, which is valid in the deep-LPM regime of an infinite medium. We also find qualitative agreement of our implementation with calculations in a finite and expanding medium, but future improvements are necessary for added precision at small path length. This work benefits transport model-based studies and the usage of these models in the phenomenological extraction of the jet transport coefficient.

We calculated rates of ${\beta }^{-}$ decay to both continuum and bound states separately for some fully ionized (bare) atoms in the mass range $\mathrm{A}\approx 60–240$. One of the motivations of this work is that the previous theoretical calculations were very old and/or informatically incomplete. Probably no theoretical study on this subject has been done in the last three decades. For the calculation, we have derived a framework from the usual ${\beta }^{-}$ decay theory used by previous authors. Dependence of the calculated rates on the nuclear radius and neutral atom $Q$ values have been examined. We have used the latest experimental data for nuclear and atomic observables, such as ${\beta }^{-}$ decay $Q$ values, ionization energy, neutral atom ${\beta }^{-}$ decay branchings, and neutral atom half-lives. Results of ${\beta }^{-}$ decay rates for decay to continuum and bound states and the enhancement factor due to the bound state decay for a number of nuclei have been tabulated and compared with the previously calculated values, if available. The effective rate or half-life calculated for a bare atom might be helpful to set a limit on the maximum enhancement due to bound state decay. Finally, ${\beta }^{-}$ decay branching for a bare atom has been calculated. The changes in branching in a bare atom compared with that in a neutral atom and for the first time branching flip for a few cases have been obtained. The reason for this branching change has been understood in terms of $Q$ values of the transitions in the neutral and bare atoms. Verification of this branching change or flip phenomenon in bare-atom decay might be of interest for future experiments.

Low-lying negative-parity states in ${}^{11}\mathrm{Be}$ having dominant $p$-wave neutron configurations were studied using the ${}^{12}\mathrm{B}(d,{}^3\mathrm{He}){}^{11}\mathrm{Be}$ proton-removal reaction in inverse kinematics. The $1/2_1^{-}$ state at 0.32 MeV, the $3/2_1^{-}$ state at 2.56 MeV, and one or both of the states including the $5/2_1^{-}$ level at 3.89 MeV and the $3/2_2^{-}$ level at 3.96 MeV were populated in the present reaction. Spectroscopic factors were determined from the differential cross sections using a distorted wave Born approximation method. The $p$-wave proton removal strengths were well described by the shell model calculations while the Nilsson model calculation underestimates the spectroscopic factors for the higher excited states. Results from both variational Monte Carlo and no-core shell-model calculations were also compared with the experimental observations.

Recent calculations of nuclear structure corrections to the Lamb shift in light muonic atoms are based on an expansion in a parameter $\eta$, where only terms up to second order are retained. The parameter $\eta$ can be shown to be proportional to $\sqrt{m_r/m_p}$, where $m_r$ is the reduced mass of the muon-nucleus system and $m_p$ is the proton mass, so that it is small and the expansion is expected to converge. However, practical implementations show that the $\eta$ convergence may be slower than expected. In this work, we probe the uncertainties due to this expansion using a different formalism, which is based on a multipole expansion of the longitudinal and transverse response functions. We refer to this alternative expansion as the $\eta$-less formalism. We generalize this formalism to account for the cancellation of elastic terms such as the third Zemach moment (or Friar moment) and embed it in a computationally efficient framework. We implement and test this approach in the case of muonic deuterium. The comparison of results in the point nucleon limit for both methods achieve subpercent agreement. When nucleon form factors are introduced, we find $4\%$ and $2\%$ differences in the third Zemach moment and nuclear polarizability, respectively, compared to the $\eta$-less expansion, indicating that the nucleon form factor approximations by Ji et al. [J. Phys. G 45, 093002 (2018)] should be improved. However, we find that the sum of these terms removes this dependence and the uncertainty due to the $\eta$ expansion and the related second-order approximation in the nucleon form factors amounts only to $0.2\%$ and thus is fully justified in muonic deuterium. This computationally efficient framework paves the way for further studies in light muonic systems with more than two nucleons, where controlling and reducing uncertainties in nuclear structure corrections is key to the experimental efforts of the CREMA Collaboration.

In the string melting version of a multiphase transport model, the hadronization algorithm has been improved by favoring parton combinations close in not only coordinate space but also momentum space. Formation probabilities of mesons, baryons, and antibaryons during hadronization are determined by their corresponding Wigner functions for the valence parton combinations with no free parameters, and the net baryon, electric, and strangeness charges are conserved during quark coalescence. Effects of the hadronization on anisotropic flows, collision energy dependence of the proton directed flow, relative particle yield ratios, as well as dihadron correlations in relativistic heavy-ion collisions at the energies ranging from Relativistic Heavy Ion Collider beam energy scan to Large Hadron Collider have been extensively discussed.

In order to investigate the systematic of fusion incompleteness in reactions induced by $\alpha$ cluster projectiles, a detailed study was carried out using the ${}^{20}\mathrm{Ne}+{}^{165}\mathrm{Ho}$ system at energies above the barrier. Measurements of the excitation function (EF) of the observed evaporation residues (ERs) were carried out by employing the offline characteristic $\gamma$-ray detection method. The EFs of the ERs populated through $xn/pxn$ channels were found to be in good agreement with the prediction of the statistical model code pace4, whereas the EF of the ERs populated through the $\alpha$ emitting channels shows an enhancement over the pace4 prediction. The degree of fusion incompleteness in the ${}^{20}\mathrm{Ne}+{}^{165}\mathrm{Ho}$ reaction is estimated by comparing the fusion EF with coupled channels calculations and the extracted fusion function with the universal fusion function. The influence of input angular momentum on fusion reaction dynamics is explored in light of the sum-rule model. An attempt has also been made to examine the dependence of incomplete fusion probability on various entrance channel parameters.

Asymmetric low-energy fission of neutron-deficient nuclei around lead is addressed with the measurement of fragment mass and total kinetic energy properties for the fissioning system ${}^{198}\mathrm{Po}$ produced in heavy-ion fusion. Interpretation of the measurement for such a transitional nucleus at finite excitation energy is challenging. The presence of asymmetric partitions is suggested by the observed weak dependence of the total kinetic energy on mass and by the nonmonotonic evolution of the fragment-mass distribution width with excitation energy. The interpretation is supported by microscopic model calculations as well as by the results of an advanced semiempirical code. Combined with previous experiments in the region, the present measurement contributes to establish the evolution of the fragment-mass distribution as a function of the fissioning system. The connection between the “new” and the “old” islands of asymmetric fission is discussed.

We investigate excited states of ${}^{18}\mathrm{O}$ by using the antisymmetrized molecular dynamics. It is found that five different types of cluster states exist which we call ${}^{14}\mathrm{C}+\alpha$, higher-nodal ${}^{14}\mathrm{C}+\alpha$, two molecular states, and $4\alpha$ linear-chain. The calculated $\alpha$-decay widths are compared with the observed data. The higher-nodal ${}^{14}\mathrm{C}+\alpha$ cluster states reasonably agree with resonances reported by the recent experiments. We predict that the $\alpha$-particle emission is dominant for the ${}^{14}\mathrm{C}+\alpha$ cluster states while the molecular states prefer the ${}^6\mathrm{He}$ emission.

The enhancement of $B_c$ production is expected due to formation of quark-gluon plasma in heavy-ion collisions. However, it is also expected that the production rate of $B_c$ meson can be affected by its interactions with comovers in hot hadronic gas. To study this effect we calculate the dissociation cross sections of $B_c$ meson by $\pi$ and $\rho$ mesons, including anomalous processes using an effective hadronic Lagrangian. Thermal averaged cross sections of $B_c$ are evaluated with a form factor when a cutoff parameter in it is 1 and 2 GeV. Using these cross sections in the kinetic equation, we study the time evolution of $B_c$ mesons in hot hadronic matter formed at LHC. We find that the effect of interactions with comovers is small but not negligible.

In a multiphase transport model with the initial electric quadrupole moment, we studied and discussed the charge asymmetry ($A_{\mathrm{ch}}$) dependence of flow at varied kinematic windows in semicentral $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}$ = 200 GeV. We then proposed a novel correlator $W$ which specifically focuses on the difference of elliptic flow between positively and negatively charged hadrons induced by the chiral magnetic wave and, more importantly, is irrelevant to the ambiguous $A_{\mathrm{ch}}$. We found that the distribution of the second-order correlator $W_2$ displays a convex structure in the absence of the quadrupole and a concave shape in the presence of the quadrupole. We then studied the response of $W_n$ for both signal and resonance background in a toy model and in analytical calculation. Such a method provides a new way to detect the chiral magnetic wave.

Charge-dependent anisotropy Fourier coefficients ($v_n$) of particle azimuthal distributions are measured in $p\mathrm{Pb}$ and $\mathrm{PbPb}$ collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=5.02\mathrm{TeV}$ with the CMS detector at the LHC. The normalized difference in the second-order anisotropy coefficients ($v_2$) between positively and negatively charged particles is found to depend linearly on the observed event charge asymmetry with comparable slopes for both $p\mathrm{Pb}$ and $\mathrm{PbPb}$ collisions over a wide range of charged particle multiplicity. In $\mathrm{PbPb}$, the third-order anisotropy coefficient $v_3$ shows a similar linear dependence with the same slope as seen for $v_2$. The observed similarities between the $v_2$ slopes for $p\mathrm{Pb}$ and $\mathrm{PbPb}$, as well as the similar slopes for $v_2$ and $v_3$ in $\mathrm{PbPb}$, are compatible with expectations based on local charge conservation in the decay of clusters or resonances, and constitute a challenge to the hypothesis that, at LHC energies, the observed charge asymmetry dependence of $v_2$ in heavy ion collisions arises from a chiral magnetic wave.