We study the quasifission and fusion-fission lifetimes for a number of fusion reactions used to synthesize the superheavy element $Z=120$ using a statistical method within the framework of the dinuclear system model. In particular, influence of the target orientation and angular momentum on such lifetimes have been investigated. The quasifission and fusion-fission lifetimes have been compared very well with that of available experiments on successful superheavy element synthesis. We notice further the predicted quasifission and fusion-fission lifetimes of the projectile-target combinations used for the synthesis of the superheavy element $Z=120$ also show the similar trend. Furthermore, the fusion-fission lifetime is seen to somewhat decrease with the increase of the angular momentum as well as beam energy. Little effect is seen on fusion barrier of the reaction and fission barrier of superheavy compound nucleus. Variation of quasifission lifetime is also not much with orientation angle, beam energy and fission barrier of the superheavy compound nuclei. Hence, this lifetime study does not provide any good reason why the attempted reactions have failed to synthesize the superheavy nuclei $Z=120$. Furthermore, consideration of the fusion barrier, fissility, mass asymmetry, deformation parameter, fission barrier, etc., leads us to reveal that optimal colliding energy is important to have the largest evaporation residue cross section for any chosen reaction so that it is well within the measurable limit for a specific experimental set up.

The initial conditions in heavy-ion collisions are calculated in many different frameworks. The importance of nucleon position fluctuations within the nucleus and subnucleon structure has been established when modeling initial conditions for input to hydrodynamic calculations. However, there remain outstanding puzzles regarding these initial conditions, including the measurement of the near equivalence of the elliptical $v_2$ and triangular $v_3$ flow coefficients in ultracentral 0–1% $\mathrm{Pb}+\mathrm{Pb}$ collisions at the CERN Large Hadron Collider. Recently a calculation termed magma incorporating gluonic hot spots via two-point correlators in the color glass condensate framework, and no nucleons, provided a simultaneous match to these flow coefficients measured by the ATLAS experiment, including in ultracentral 0–1% collisions. Our calculations reveal that the magma initial conditions do not describe the experimental data when run through full hydrodynamic sonic simulations or when the hot spots from one nucleus resolve hot spots from the other nucleus, as predicted in the color glass condensate framework. We also explore alternative initial condition calculations and discuss their implications.

The $\beta$ decay of neutron-rich ${}^{129}\mathrm{In}$ into ${}^{129}\mathrm{Sn}$ was studied using the GRIFFIN spectrometer at the ISAC facility at TRIUMF. The study observed the half-lives of the ground state and each of the $\beta$-decaying isomers. The level scheme of ${}^{129}\mathrm{Sn}$ has been expanded with thirty-one new $\gamma$-ray transitions and nine new excited levels, leading to a reevaluation of the $\beta$ branching ratios and level spin assignments. The observation of the $\beta$ decay of the ($29/2^{+}$) 1911-keV isomeric state in ${}^{129}\mathrm{In}$ is reported for the first time, with a branching ratio of 2.0(5)$\%$.

In this paper, we have investigated the sensitivity of fusion cross section and the barrier distribution data with respect to the choice of the potential parameters. To ascertain this, the fusion dynamics of ${}^{16}\mathrm{O}+{}^{70,72,73,74,76}\mathrm{Ge}$ and ${}^{18}\mathrm{O}+{}^{74}\mathrm{Ge}$ reactions at near and sub-barrier energies have been examined. In the present study, we have used the one-dimensional Wong formula, symmetric-asymmetric Gaussian barrier distribution (SAGBD) model, and coupled channel approach. For theoretical estimations, the Woods-Saxon form of nuclear potential has been adopted, and it has been found that both the fusion cross section and barrier distribution are quite sensitive to the choice of potential parameters in the entire range of incident energies. Calculations based on the Wong formula are significantly smaller than the sub-barrier fusion data, which has clearly suggested that the couplings to the nuclear structure's degrees of freedom of the colliding nuclei are needed to reproduce the experimental data. On the other hand, in the SAGBD model calculations the multidimensional character of nucleus-nucleus potential has been incorporated and it has reasonably recovered both the fusion cross-section data and the barrier distribution data of ${}^{16}\mathrm{O}+{}^{70,72,73,74,76}\mathrm{Ge}$ and ${}^{18}\mathrm{O}+{}^{74}\mathrm{Ge}$ reactions. In the SAGBD model, channel coupling parameter $\lambda$ has been determined from barrier distribution and hence $\lambda$ is related to the various channel coupling effects which have arisen because of the nuclear structure of the participating nuclei. The increase in $\lambda$ with an increase in target isotopic mass has clearly indicated that there are shape transition effects in Ge isotopes, which change their shape from spherical symmetry to prolate deformed shape as one moves from ${}^{70}\mathrm{Ge}$ to ${}^{76}\mathrm{Ge}$. Similarly, the percentage reduction of effective fusion barrier $V_{\mathit{CBRED}}$ with respect to uncoupled Coulomb barrier has also shown an increasing trend with the increase in target isotopic mass. In order to confirm the shape transition effects, the coupled channel calculations have been performed by using the code CCFULL. The present coupled channel analysis has clearly pointed out the importance of nuclear structure degrees of freedom of participating nuclei in the sub-barrier region. Similar results have also been evident from SAGBD analysis. Hence the model predictions incorporate the contributions from vibrational excitations and/or static deformation in the fusion of ${}^{16}\mathrm{O}+{}^{70,72,73,74,76}\mathrm{Ge}$ reactions. For the ${}^{18}\mathrm{O}+{}^{74}\mathrm{Ge}$ reaction, the vibrational excitations along with the neutron transfer channel have led to larger sub-barrier fusion enhancement and their influences have been automatically included in the SAGBD calculations. Furthermore, ${}^{16}\mathrm{O}+{}^{76}\mathrm{Ge}$ and ${}^{18}\mathrm{O}+{}^{74}\mathrm{Ge}$ reactions have formed the same compound nucleus ${}^{92}\mathrm{Zr}$ via different entrance channels. Their comparative study has indicated that the effect of the neutron transfer channel has dominated over the entrance channel mass asymmetry effects. In addition, the minimum value of ${\chi }^2$ that has been obtained for the SAGBD calculations is consistent with that of the coupled channel calculations.

We compute the free energy of asymmetric nuclear matter in a Brueckner-Hartree-Fock approach at finite temperature, paying particular attention to the dependence on isospin asymmetry. The first- and second-order symmetry energies are determined as functions of density and temperature and useful parametrizations are provided. We find small deviations from the quadratic isospin-asymmetry dependence and very small corresponding effects on (proto)neutron star structure.

I have applied a simple two-state mixing model to $E2$ strengths from a recent ${}^{94}\mathrm{Zr}(n,n^{\prime }\gamma )$ experiment in order to obtain the mixing amplitudes between spherical and deformed basis states in ${}^{94}\mathrm{Zr}$. The fits also provide the transition matrix elements connecting the basis states.

Low-lying dipole transitions in ${}^{207}\mathrm{Pb}$ were measured via nuclear photon scattering using a quasimonochromatic, linearly polarized photon beam. The spins and/or parities of the states observed in ${}^{207}\mathrm{Pb}$ were determined from the intensity asymmetry of resonantly scattered $\gamma$ rays with respect to the polarization plane of the incident photon beam. The electric ($E1$) and magnetic ($M1$) dipole strengths were obtained for excitation energies from 5.49 to 6.75 MeV. The present experimental results, combined with $(\gamma ,n)$ data from the literature, were used to investigate the $E1$ and $M1$ photoabsorption cross sections near the neutron separation energy by comparison with predictions from the particle-vibration coupling with the quasiparticle random-phase approximation model.

We provide a framework to estimate the systematic uncertainties in chemical freeze-out parameters extracted from ${\chi }^2$ analysis of thermal models, using hadron multiplicity ratios in relativistic heavy-ion collision experiments. Using a well known technique of graph theory, we construct all possible sets of independent ratios from available hadron yields and perform ${\chi }^2$ minimization on each set. We show that even for ten hadron yields, one obtains a large number (${10}^8$) of independent sets which results in a distribution of extracted freeze-out parameters. We analyze these distributions and compare our results for chemical freeze-out parameters and associated systematic uncertainties with previous results available in the literature.

Quasinuclear systems, representing nuclei with variable size, are studied to investigate the occurrence of the spin-orbit term in the nuclear mean field in the transition from infinite nuclear matter to finite nuclei. Relativistic as well as nonrelativistic mean-field calculations based on models for the nucleon-nucleon (NN) interaction, which fit the NN scattering data, are considered. A very strong correlation between the strength of the spin-orbit term and radius of the nuclear system is observed. The origin of the spin-orbit term is analyzed by inspecting the contributions of the different partial waves and various mesons in a one-boson-exchange model of the NN interaction. Also results for a realistic interaction model based on chiral effective field theory including the contribution of three-nucleon interactions are discussed. The influence of correlation effects and the enhancement of the small component of Dirac spinors for nucleons in the nuclear medium are discussed.

We estimate the production of electromagnetic radiation (real and virtual photons) from the early, pre-equilibrium stage of relativistic heavy-ion collisions. The parton dynamics are obtained as a solution of the Boltzmann equation in the Fokker-Planck diffusion limit. The photon and dilepton rates are integrated and the obtained yields are compared with those from standard sources and with available experimental data. The nonequilibrium electromagnetic contribution can be nonnegligible at the current LHC energies, depending on the saturation scale. Predictions are made for $\mathrm{Pb}+\mathrm{Pb}$ at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$.

We merge the dispersive relation approach and the ab initio method to compute nuclear structure corrections to the Lamb shift in muonic deuterium. We calculate the deuteron response functions and corresponding uncertainties up to next-to-next-to-next-to-leading order in chiral effective field theory and compare our results to selected electromagnetic data to test the validity of the theory. We then feed response functions calculated over a wide range of kinematics to the dispersion-theory formalism and show that an improved accuracy is obtained compared to that with the use of available experimental data in the dispersive analysis. This opens up the possibility of applying this hybrid method to other light muonic atoms and supplementing experimental data with ab initio theory for kinematics where data are scarce or difficult to measure with the goal of reducing uncertainties in estimates of nuclear structure effects in atomic spectroscopy.

To extract the charge radius of the proton, $r_p$, from the electron scattering data, the PRad collaboration at Jefferson Lab has developed a rigorous framework for finding the best functional forms—the fitters—for a robust extraction of $r_p$ from a wide variety of sample functions for the range and uncertainties of the PRad data. In this paper we utilize and further develop this framework. Herein we discuss methods for searching for the best fitter candidates as well as a procedure for testing the robustness of extraction of the deuteron charge radius, $r_d$, from parametrizations based on elastic electron-deuteron scattering data. The ansatz proposed in this paper for the robust extraction of $r_d$, for the proposed low-$Q^2$ DRad experiment at Jefferson Lab, can be further improved once there are more data.

We study phenomenologically a ${\mathrm{\Xi }}^{-}$ production spectrum of the ${}^9\mathrm{Be}(K^{-},K^{+})$ reaction at 1.8 GeV/$c$ within the distorted-wave impulse approximation using the optimal Fermi-averaged $K^{-}p\to K^{+}{\mathrm{\Xi }}^{-}$ amplitude. We attempt to clarify properties of a $\mathrm{\Xi }$-nucleus potential for ${\mathrm{\Xi }}^{-}\text{−}{}^8\mathrm{Li}$, comparing the calculated spectrum with the data of the BNL-E906 experiment. The results show a weak attraction in the $\mathrm{\Xi }$-nucleus potential for ${\mathrm{\Xi }}^{-}\text{−}{}^8\mathrm{Li}$, which can sufficiently explain the data in the ${\mathrm{\Xi }}^{-}$ quasifree region. The strength of $V_0^{\mathrm{\Xi }}=-17\pm 6$ MeV is favored within the Woods-Saxon potential, accompanied by the reasonable absorption of $W_0^{\mathrm{\Xi }}=-5$ MeV for ${\mathrm{\Xi }}^{-}p\to {\mathrm{\Xi }}^{0}n$ and ${\mathrm{\Xi }}^{-}p\to \mathrm{\Lambda }\mathrm{\Lambda }$ transitions in nuclear medium. It is difficult to determine the value of $W_0^{\mathrm{\Xi }}$ from the data due to the insufficient resolution of 14.7 MeV FWHM. The energy dependence of the Fermi-averaged $K^{-}p\to K^{+}{\mathrm{\Xi }}^{-}$ amplitude is also confirmed by this analysis, and its importance in the nuclear $(K^{-},K^{+})$ reaction is emphasized.

Elastic scattering and breakup angular distributions of the weakly bound radioactive nucleus ${}^8\mathrm{B}$ on a ${}^{208}\mathrm{Pb}$ target at an incident energy of 238 MeV, which corresponds to four times the Coulomb barrier, have been measured at the HIRFL-RIBLL facility (Institute of Modern Physics, Lanzhou). The data have been analyzed using the optical model and the continuum discretized coupled channels (CDCC) formalism. The measured and calculated elastic scattering angular distributions do not show any significant Coulomb rainbow suppression. The angular distribution for the breakup reaction was measured for the first time at this energy. The angular distribution of the ${}^7\mathrm{Be}$ fragments could be reproduced considering elastic plus nonelastic breakup contributions, with the former evaluated with the CDCC calculations and the latter with the model of Ichimura, Austern, and Vincent [Phys. Rev. C 32, 431 (1985)]. The comparison of the breakup cross section of ${}^8\mathrm{B}$ with that of ${}^{11}\mathrm{Be}$ suggests that the Coulomb and centrifugal barriers encountered by the valence proton may suppress the breakup cross section.

We perform a systematic study of the spin polarization of hyperons in heavy ion collisions using the music hydrodynamic model with a multiphase transport preequilibrium dynamics. Our model calculations nicely describe the measured collision energy, centrality, rapidity, and $p_T$ dependence of the $\mathrm{\Lambda }$ polarization. We also study and predict the global spin polarization of ${\mathrm{\Xi }}^{-}$ and ${\mathrm{\Omega }}^{-}$ as a function of collision energy, which provides a baseline for the studies of the magnetic moment, spin, and mass dependence of the spin polarization. For the local spin polarization, we calculate the radial and azimuthal components of the transverse $\mathrm{\Lambda }$ polarization and find specific modulating behavior which could reflect the circular vortical structure. However, our model fails to describe the azimuthal-angle dependence of the longitudinal and transverse $\mathrm{\Lambda }$ polarizations, which indicates that the hydrodynamic framework with the spin Cooper-Frye formula under the assumption of thermal equilibrium of the spin degree of freedom needs to be improved.

A Euclidean formulation of relativistic quantum mechanics for systems of a finite number of degrees of freedom is discussed. Relativistic treatments of quantum theory are needed to study hadronic systems at subhadronic distance scales. While direct interaction approaches to relativistic quantum mechanics have proved to be useful, they have two disadvantages. One is that cluster properties are difficult to realize for systems of more than two particles. The second is that the relation to quantum field theories is indirect. Euclidean formulations of relativistic quantum mechanics provide an alternative representation that does not have these difficulties. More surprising, the theory can be formulated entirely in the Euclidean representation without the need for analytic continuation. In this work a Euclidean representation of a relativistic $N$-particle system is discussed. Kernels for systems of $N$ free particles of any spin are given and shown to be reflection positive. Explicit formulas for generators of the Poincaré group for any spin are constructed and shown to be self-adjoint on the Euclidean representation of the Hilbert space. The structure of correlations that preserve both the Euclidean covariance and reflection positivity is discussed.

The essence of the quasi-SU(3) coupling scheme suggested by Zuker et al. is that the high-$j$ intruder orbit alone is insufficient to induce required large collectivity, and it is necessary for the high-$j$ orbit to correlate through the quadrupole interaction with another higher-lying orbit with $\mathrm{\Delta }j=2$. To extend this idea to the medium-heavy mass region, we investigate the systematics of energy levels and $B\left(E2\right)$ values for Sn, Te, Xe, Ba, Ce, Nd, and Sm isotopes by applying the recently proposed realistic PMMU shell model. The calculations are performed by using the projected Hartree-Fock-Bogolyubov plus generator coordinate method in the model space of ($1g_{9/2},1g_{7/2},2d_{5/2},2d_{3/2},3s_{1/2},1h_{11/2}$). The calculations describe well the experimental data over a wide range of nuclei. However, it is found that, in some nuclei close to the neutron midshell, ${}^{124,126}\mathrm{Ce}$, ${}^{130,132}\mathrm{Nd}$, and ${}^{134}\mathrm{Sm}$, the calculated $B(E2;2_1^{+}\to 0_1^{+})$ values underestimate the data considerably. This problem can be resolved by inclusion of the $2f_{7/2}$ orbit into the model space, which, with $1h_{11/2}$, forms a quasi-SU(3) coupling scheme. It is shown that the $QQ$ interaction between the SU(3)-partner $1h_{11/2}\text{−}2f_{7/2}$ is a driving force for enhanced $E2$ collectivity in the above nuclei and is responsible for the shape evolution in Nd isotopes. In addition, the participation of the $2f_{7/2}$ orbit in the model space favors prolate shape in the ground state of $N\le 76$ isotopes, thus subverting the oblate result from the same calculation but without $2f_{7/2}$.

A new convenient method for accurate theoretical calculations of quantities of traditional theory of nuclear reactions such as widths of resonances (including subthreshold), and asymptotic normalization coefficients is proposed. This provides a step towards the development of a new alternative technique for an ab initio description of light nuclei spectroscopic data. As an illustration of this method, the computational results for all relevant two-body decay channels of all known and some theoretically predicted states of ${}^7\mathrm{Li}$ nucleus are shown. Well proven on a large amount of data, the Daejeon16 potential was used in the calculations. The greatest part of the results turn out to be in a good agreement with the experimental data contained in spectroscopic tables.

We obtained a density-dependent analytical expression of binding energy per nucleon for different neutron-proton asymmetry of the nuclear matter (NM) with a polynomial fitting, which manifests the results of effective-field theory motivated relativistic mean-field (E-RMF) model. This expression has the edge over the Brückner energy density functional [Phys. Rev. 171, 1188 (1968)] since it resolves the Coster-Band problem. The NM parameters like incompressibility, neutron pressure, symmetry energy, and its derivatives are calculated using the acquired expression of energy per nucleon. Furthermore, the weight function calculated by E-RMF densities are folded with calculated NM parameters within coherent density fluctuation model to find the properties of closed or semiclosed-shell even-even ${}^{16}\mathrm{O}, {}^{40}\mathrm{Ca}, {}^{48}\mathrm{Ca}, {}^{56}\mathrm{Ni}, {}^{90}\mathrm{Zr}, {}^{116}\mathrm{Sn}$, and ${}^{208}\mathrm{Pb}$ nuclei. The values obtained for the neutron pressure $P^A$, symmetry energy $S^A$, and its derivative $L_{\mathrm{sym}}^A$ known as the slope parameter lie within a narrow domain whereas there is a large variation in isoscalar incompressibility $K^A$ and surface incompressibility $K_{\mathrm{sym}}^A$ while moving from light to heavy nuclei. The sizable variation in $K^A$ and $K_{\mathrm{sym}}^A$ for light and heavy nuclei depicts their structural dependence due to the peculiar density distribution of each nucleus. A comparison of surface quantities calculated in the present work has also been made with ones obtained via Brückner energy density functional.