The determination of the color force in a quark-gluon plasma (QGP) is a key objective in the investigation of strong-interaction matter. Open and hidden heavy-flavor observables in heavy-ion collisions (HICs) are believed to provide insights into this problem by comparing calculations of heavy-quark (HQ) and quarkonium transport with pertinent experimental data. In this work, we utilize the $T$-matrix formalism to compute charm-quark transport coefficients for various input potentials previously extracted from simultaneous fits to lattice-QCD data for HQ free energies, quarkonium correlators, and the QGP equation of state. We investigate the impact of off-shell effects (spectral functions) in the QGP medium on the HQ transport, and compare to earlier results using the free or internal HQ energies as potential proxies. We then employ the transport coefficients in relativistic Langevin simulations for HICs to test the sensitivity of heavy-flavor observables to the HQ interactions in the QGP. We find that a strongly coupled $T$-matrix solution generates a HQ elliptic flow comparable to the results from the internal energy at low momentum, driven by a long-range remnant of the confining force, while falling off stronger with increasing three-momentum. The weakly coupled $T$-matrix solution, whose underlying potential is close to the free energy, leads to an elliptic flow well below the experimentally observed range.

The effect of strange interactions in neutron star matter and the role of the strange meson-hyperon couplings are studied in a relativistic quark model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to $\sigma , \omega , \rho , {\sigma }^{*}$, and $\varphi$ mesons through mean-field approximations. The meson-baryon couplings are fixed through the SU(6) spin-flavor symmetry and the SU(3) flavor symmetry to determine the hadronic equation of state (EoS). We find that the SU(3) coupling set gives the potential depth between ${\mathrm{\Lambda }}^{\prime }\mathrm{s}$ around $-5$ MeV and favors a stiffer EoS. Using the stiffest EoS from the SU(3) we determine the tidal Love number $k_2$, the tidal deformability $\lambda$, and the dimensionless tidal deformability ${\mathrm{\Lambda }}_D$. We obtain a value of ${\mathrm{\Lambda }}_D=483$ corresponding to a $1.4M_{\odot }$ star while the weighted tidal deformability $\tilde{\mathrm{\Lambda }}=624$ for a symmetric binary system of chirp mass $\mathcal{M}=1.188M_{\odot }$. The radius for the canonical neutron star is found to be 13.1 km.

High-spin states in ${}^{89}\mathrm{Zr}$ were populated in the ${}^{80}\mathrm{Se}({}^{13}\mathrm{C},4n)$ reaction, and $\gamma$-ray coincidences were measured using the Indian National Gamma Array. The level scheme of ${}^{89}\mathrm{Zr}$ has been extended up to spin $I=49/2$ with the observation of a new dipole band. Directional correlation and polarization asymmetries of the $\gamma$ rays have been measured to determine spin and parity of the levels. Line shapes of several transitions have been analyzed to determine lifetimes of the levels. Possible configurations of the band have been discussed using the cranked Nilsson-Strutinsky model. The calculations suggest a triaxial shape of the nucleus at high spins, and the band may represent rotation of the nucleus about the longest axis.

Excitation functions for fusion-$xn$ evaporation reaction channels induced by ${}^{48}\mathrm{Ca}$ as well as by heavier projectiles (usually leading to smaller cross sections) on actinide targets were calculated in the framework of the fusion-by-diffusion (FBD) model. For the first time, in this approach, channels in which a proton ($pxn$) or alpha particle ($\alpha xn$) is evaporated have been included in the first step of the de-excitation cascade. To calculate the synthesis cross sections entry data such as fission barriers, ground-state masses, deformations, and shell effects of the superheavy nuclei calculated in a consistent way within the Warsaw macroscopic-microscopic model were used. The only adjustable parameter of the FBD model is the injection point distance $s_{inj}$. The systematics determined in our previous analysis of experimental cross sections for the synthesis of superheavy nuclei of $Z=114–118$ has been used. Excitation functions for the synthesis of selected (cross section above a few fb) new superheavy nuclides in the range of atomic numbers 112–120 are presented. Observation of 21 new heaviest isotopes is also predicted. A realistic discussion of the FBD model uncertainties is presented for the first time.

The pygmy dipole resonance (PDR) of ${}^{208}\mathrm{Pb}$ is studied with random phase approximation method. The effect of the neutron-proton mass splitting is discussed in the framework of relativistic mean field theory via including the scalar-isovector meson $\delta$ explicitly. The model is calibrated with nuclear bulk properties as well as finite nuclei data, and is further checked by terrestrial experimental and astrophysical constraints. The inclusion of $\delta$ meson reduces the neutron skin thickness of ${}^{208}\mathrm{Pb}$ as well as ${}^{48}\mathrm{Ca}$, which are turned out to be closely related. The energy of pygmy dipole resonance is in a large extent dominated by the excitations of neutrons near the Fermi surface. We found that the peak positions of the giant dipole resonance (GDR) and the PDR are sensitive to the nucleon-meson coupling in the scalar-isovector channel. A linear correlation between the neutron-proton effective mass splitting at saturation density and the relative offset of GDR and PDR is identified in ${}^{208}\mathrm{Pb}$.

New experimental results for the elastic scattering of ${}^6\mathrm{He}$ on ${}^{64}\mathrm{Zn}$ at incident energies of 15.0 and 18.0 MeV and ${}^4\mathrm{He}$ at 17.5 MeV along with results already published at 10.0 and 13.6 MeV, are presented. Elastic and $\alpha$ experimental cross sections are compared with coupled-reaction-channel, continuum-discretized coupled-channel, and DWBA inclusive-breakup models. The large yield of $\alpha$ particles observed at all measured energies can be explained by considering a nonelastic breakup mechanism.

The phenomenon of liquid-gas phase transition occurring in heavy-ion collisions at intermediate energies is a subject of contemporary interest. In statistical models of fragmentation, the liquid drop model is generally used to calculate the ground-state binding energies of the fragments. It is well known that the surface and symmetry energy of the hot fragments at the low-density freeze-out can be considerably modified. In addition to this, the level-density parameter also has a wide variation. The effect of variation of these parameters is studied on fragmentation observables which are related to the nuclear liquid-gas phase transition. The canonical thermodynamical model which has been very successful in describing the phenomenon of fragmentation is used for the study. The shift in transition temperature owing to the variation in liquid drop model parameters has been examined.

The recently developed technique of Cyclotron Radiation Emission Spectroscopy (CRES) uses frequency information from the cyclotron motion of an electron in a magnetic bottle to infer its kinetic energy. Here we derive the expected radio-frequency signal from an electron in a waveguide CRES apparatus from first principles. We demonstrate that the frequency-domain signal is rich in information about the electron's kinematic parameters and extract a set of measurables that in a suitably designed system are sufficient for disentangling the electron's kinetic energy from the rest of its kinematic features. This lays the groundwork for high-resolution energy measurements in future CRES experiments, such as the Project 8 neutrino mass measurement.

The ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$ reaction, an important component of stellar helium burning, plays a key role in nuclear astrophysics. It has direct impact on the evolution and final state of massive stars, while also influencing the elemental abundances resulting from nucleosynthesis in such stars. Providing a reliable estimate for the energy dependence of this reaction at stellar helium burning temperatures has been a major goal for the field. In this work, we study the role of potential new measurements of the inverse reaction, ${}^{16}\mathrm{O}(\gamma ,\alpha ){}^{12}\mathrm{C}$, in reducing the overall uncertainty. A multilevel $R$-matrix analysis is used to make extrapolations of the astrophysical $S$ factor for this reaction to the stellar energy of 300 keV. The statistical precision of the $S$-factor extrapolation is determined by performing multiple fits to existing $E1$ and $E2$ ground-state capture data, including the impact of possible future measurements of the ${}^{16}\mathrm{O}(\gamma ,\alpha ){}^{12}\mathrm{C}$ reaction. In particular, we consider a proposed Jefferson Laboratory (JLab) experiment that will make use of a high-intensity low-energy bremsstrahlung beam that impinges on an oxygen-rich single-fluid bubble chamber in order to measure the total cross section for the inverse reaction. The importance of low-energy data as well as high-precision data is investigated.

Fission neutron multiplicity data are imperative for nuclear models that support criticality safety, nuclear nonproliferation, and stockpile stewardship. This work presents the first experimental measurement to determine the average neutron multiplicity ($\overline{\nu }$) and the neutron multiplicity distribution using a surrogate reaction. ${}^{241}\mathrm{Pu}$ has a short half-life of 14.3 yr. To circumvent experimental difficulties, inelastic scattering of 53.96-MeV $\alpha$ particles on ${}^{242}\mathrm{Pu}$ served as a surrogate for ${}^{241}\mathrm{Pu}(n,f)$. The present text reports and discusses the average neutron multiplicity, in addition to the neutron multiplicity moments and distribution for equivalent neutron energies up to 20 MeV. The $\overline{\nu }$ measured in this experiment agrees with previous measurements until 12 MeV, where discrepancies arise due to preequilibrium neutron emission.

The dissociation of heavy quarkonia in the constrained space is calculated at leading order compared with that in an infinitely large medium. To deal with the summation of the discrete spectrum, a modified Euler-Maclaurin formula is developed as our numerical algorithm. We find that with the constraint in space, the dissociation of quarkonia at early time after the collision becomes negligible if the QGP and quarkonia are formed.

The present work constitutes a detailed study of neutral-current (NC) supernova-neutrino scattering off the stable even-even lead isotopes ${}^{204,206,208}\mathrm{Pb}$. This is a continuation of our previous work [Almosly et al., Phys. Rev. C. 94, 044614 (2016)] where we investigated charged-current processes on the same nuclei. As in the previous work, we have adopted the quasiparticle random-phase approximation (QRPA) as the theory framework and use three different Skyrme interactions to build the involved nuclear wave functions. We test the Skyrme forces by computing the location of the lowest-order isovector spin-multipole giant resonances and comparing with earlier calculations. We have computed the NC cross sections for (anti)neutrino energies up to 100 MeV and estimated the nuclear responses to supernova (anti)neutrinos by folding the obtained cross sections by suitably parametrized Fermi-Dirac distributions of energies of the incoming (anti)neutrinos. We compare our results with results of earlier studies in the case of ${}^{208}\mathrm{Pb}$, which is the only lead isotope where earlier calculations are available.

Results for the three-nucleon (3N) bound state carried out using the three-dimensional (3D) formalism are presented. In this approach calculations are performed without the use of angular momentum decomposition and instead rely directly on the 3D degrees of freedom of the nucleons. In this paper, for the first time, 3D results for ${}^3\mathrm{He}$ bound state with the inclusion of the screened Coulomb potential are compared to ${}^3\mathrm{H}$ calculations. The ${}^3\mathrm{He}$ calculations were made possible largely due to a new, faster implementation of the 3N force in 3D calculations. Additionally, using these results, matrix elements of simple current operators related to the description of $\beta$ decay of the triton are given. All computations are carried out using the first generation of NNLO 2N and 3N forces from the Bochum-Bonn group.

The three-dimensional Langevin model plus a constraint on the heavy fragment deformation is used to study the fission dynamics for uranium and plutonium isotopes at low excitation energies. The potential energy surface is calculated with the macroscopic-microscopic model based on the two-center shell model. The Werner-Wheeler approximation is used to calculate the inertia tensor and the wall-and-window model is applied to calculate the friction tensor. In this work, the influence of the model parameters on the fission fragment mass distribution is investigated. The fission fragment mass distributions for ${}^{234,236,239}\mathrm{U}$ and ${}^{240}\mathrm{Pu}$ at low excitation energies are calculated and compared with the results of gef code as well as the evaluated data of ENDF/B-VIII.0. A nice agreement is found in the comparison, in which the incorporation of the constraint on the heavy fragment deformation plays an important role. In addition, the dependence of the mass distribution on the excitation energies for $n+{}^{235}\mathrm{U}$ fission is also studied within the model. Furthermore, the correlation between the elongation and mass asymmetry at the scission point and the correlations of the fission time with both the elongation and mass asymmetry are studied. This study may shed light on understanding the dynamics of the superlong channel for symmetric fission and the standard channels for asymmetric fission in the gef model and other phenomenological fission models.

Within a minimum model for neutron stars consisting of nucleons, electrons, and muons at $\beta$ equilibrium using about a dozen equations of state (EOS) from microscopic nuclear many-body theories and 40000 EOSs randomly generated using an explicitly isospin-dependent parametric EOS model for high-density neutron-rich nucleonic matter within its currently known uncertainty range, we study correlations among the $f$-mode frequency, its damping time and the tidal deformability as well as the compactness of neutron stars. Except for quark stars, both the $f$-mode frequency and damping time of canonical neutron stars are found to scale with the tidal deformability independent of the EOSs used. Applying the constraint on the tidal deformability of canonical neutron stars ${\mathrm{\Lambda }}_{1.4}={190}_{-120}^{+390}$ extracted by the LIGO+VIRGO Collaborations from their improved analyses of the GW170817 event, the $f$-mode frequency and its damping time of canonical neutron stars are limited to 1.67–2.18 kHz and 0.155–0.255 s, respectively, providing a useful guidance for the ongoing search for gravitational waves from the $f$-mode oscillations of isolated neutron stars. Moreover, assuming either or both the $f$-mode frequency and its damping time will be measured precisely in future observations with advanced gravitational wave detectors, we discuss how information about the mass and/or radius as well as the still rather elusive nuclear symmetry energies at suprasaturation densities may be extracted.

The astrophysical $S$ factor for the radiative proton capture reaction on ${}^7\mathrm{Be}$ ($S_{17}$) at low energies is affected by the $s$-wave scattering lengths. We report the measurement of elastic and inelastic scattering cross sections for the ${}^7\mathrm{Be}+p$ system in the center-of-mass energy range 0.474–2.740 MeV and center-of-mass angular range ${70}^{\circ }$–${150}^{\circ }$. A radioactive ${}^7\mathrm{Be}$ beam produced at Oak Ridge National Laboratory's (ORNL) Holifield Radioactive Ion Beam Facility was accelerated and bombarded a thin polypropylene ${\left({\mathrm{CH}}_2\right)}_n$ target. Scattered ions were detected in the segmented Silicon Detector Array. Using an $R$-matrix analysis of ORNL and Louvain-la-Neuve cross-section data, the $s$-wave scattering lengths for channel spins 1 and 2 were determined to be $17.{34}_{-1.33}^{+1.11}$ and $-3.{18}_{-0.50}^{+0.55}$ fm, respectively. The uncertainty in the $s$-wave scattering lengths reported in this work is smaller by a factor of 5–8 compared to the previous measurement, which may reduce the overall uncertainty in $S_{17}$ at zero energy. The level structure of ${}^8\mathrm{B}$ is discussed based upon the results from this work. Evidence for the existence of $0^{+}$ and $2^{+}$ levels in ${}^8\mathrm{B}$ at 1.9 and 2.21 MeV, respectively, is observed.

The neutrino mean free path in neutron matter under a strong magnetic field is evaluated for the inelastic scattering reaction and studied as a function of the neutron matter density in the range $0.05\le \rho \le 0.4{\mathrm{fm}}^{-3}$ for several temperatures up to 30 MeV and magnetic field strengths from $B=0$ up to $B={10}^{18}\mathrm{G}$. Polarized neutron matter is described within the nonrelativistic Brueckner–Hartree-Fock (BHF) approach using the Argonne V18 nucleon-nucleon potential supplemented with the Urbana IX three-nucleon force. The LNS Skyrme interaction is also used to describe polarized neutron matter in the Hartree-Fock approximation. Explicit expressions of the cross section per unit volume for the scattering of a neutrino with a spin up or spin down neutron are derived from the Fermi golden rule. Our results show that the mean free path depends strongly on the angle of the incoming neutrino, leading to an asymmetry in this quantity. This asymmetry depends on the magnetic field intensity and on the density, but it is rather independent of the temperature. For a density of $0.15{\mathrm{fm}}^{-3}$ at a temperature $\mathrm{T}=15\mathrm{MeV}$, the asymmetry in the mean free path is found to be, for both models, $\approx 0.2\%$ and $\approx 2\%$ for $B={10}^{16}$ and $B={10}^{17}\mathrm{G}$, respectively, and $\approx 15\%$ ($\approx 26\%$) for the BHF (Skyrme) model for $B={10}^{18}\mathrm{G}$.

According to theory, cluster radioactivity becomes an important decay mode in superheavy nuclei. In this work, we predict that the strongly asymmetric fission, or cluster emission, is in fact the dominant fission channel for ${}_{118}{}^{294}\mathrm{Og}_{176}$, which is currently the heaviest synthetic isotope known. Our theoretical approach incorporates important features of fission dynamics, including quantum tunneling and stochastic dynamics up to scission. We show that despite appreciable differences in static fission properties such as fission barriers and spontaneous fission lifetimes, the prediction of cluster radioactivity in ${}_{118}{}^{294}\mathrm{Og}_{176}$ is robust with respect to the details of calculations, including the choice of energy density functional, collective inertia, and strength of the dissipation term.

I have estimated the decay width of ${}^{16}\mathrm{Be}$ for a variety of decay mechanisms: $2n$ cluster decay, sequential decay through the known $5/2^{+}$ state of ${}^{15}\mathrm{Be}$, and sequential decay through a hypothetical $1/2^{+}$ state in ${}^{15}\mathrm{Be}$. Only the cluster decay width is comparable to the reported experimental width.

Background: Experimental data on some nuclei indicate a significant increase of the moment of inertia of excited states in comparison with its value in the ground state. It is interesting to investigate the reasons for this effect based on a microscopic nuclear model.

Purpose: To investigate the excitation energy dependence of the excited state moments of inertia of some even-even well deformed nuclei.

Method: The Hamiltonian of the quasiparticle phonon model with a mean field part, monopole pairing, and multipole-multipole residual interaction is used to calculate the moments of inertia of excited states.

Results: The moments of inertia of the $\gamma$-vibrational states of several rare earth nuclei and of the $1^{+}$ states of ${}^{156,158}\mathrm{Gd}$ and ${}^{160,162,164}\mathrm{Dy}$ are calculated and compared to experimental data.

Conclusion: It is shown that both the blocking effect and the Coriolis coupling between quasiparticles and the rotating core contribute significantly to the increase of the excited states' moments of inertia in comparison to the ground state value. In the case of the $1^{+}$ states a contribution of the Coriolis interaction of quasiparticles and the rotating core can be considerably larger than the blocking effect. This is one reason for a very large value of the moment of inertia of some $1^{+}$ states which can exceed the rigid body value.