A dipole sequence has been observed and investigated in the ${}^{143}\mathrm{Sm}$ nucleus populated through the heavy-ion-induced fusion-evaporation reaction and studied using the Indian National Gamma Array as the detection system. The sequence has been established as a magnetic rotation (MR) band primarily from lifetime measurements of the band members using the Doppler shift attenuation method. A configuration based on nine quasiparticles with highly asymmetric angular momentum blades has been assigned to the shears band in light of the theoretical calculations within the framework of the shears mechanism with the principal axis cranking (SPAC) model. This is hitherto the maximum number of quasiparticles along with the highest asymmetricity associated with a MR band. Furthermore, as it has followed from the SPAC calculations, the contribution of the core rotation to the angular momentum of this shears band is substantial and greater than in any other similar sequence, at least, in the neighboring nuclei. This band can thus be perceived as a unique phenomenon of shears mechanism in operation at the limits of quasiparticle excitations as manifested in MR bandlike phenomena, evolving into collectivity.

The doubly strange $\mathrm{\Xi }$ baryons provide an effective way to study a puzzle called the missing-baryons problem where both quark models and lattice gauge theory predict more baryon excited states than are seen experimentally. However, few of these excited states have been observed with any certainty. Here, high-mass ${\mathrm{\Xi }}^{*}$ states have been searched for in photoproduction with the detector of the CLAS Collaboration, and upper limits for the total cross sections have been established from threshold to $W=3.3\mathrm{GeV}$. In addition, the total cross sections of the ground-state ${\mathrm{\Xi }}^{-}$(1320) and first excited state ${\mathrm{\Xi }}^{-}$(1530) are presented, extending significantly the center-of-mass energy range of previous data.

The intimate relation between the Gamow-Teller part of the matrix element $M_{GT}^{0\nu }$ and the $2\nu \beta \beta$ closure matrix element $M_{cl}^{2\nu }$ is explained and explored. If the corresponding radial dependence $C_{cl}^{2\nu }\left(r\right)$ would be known, $M^{0\nu }$ corresponding to any mechanism responsible for the $0\nu \beta \beta$ decay can be obtained as a simple integral. However, the $M_{cl}^{2\nu }$ values, and therefore also the functions $C_{cl}^{2\nu }\left(r\right)$, sensitively depend not only on the properties of the first few $1^{+}$ states but also of higher-lying $1^{+}$ states in the intermediate odd-odd nuclei. We show that the ${\beta }^{-}$ and ${\beta }^{+}$ amplitudes of such states typically have opposite relative signs, and their contributions reduce severally the $M_{cl}^{2\nu }$ values. We suggest that demanding that $M_{cl}^{2\nu }=0$ is a sensible alternative way, within the QRPA method, of determining the amount of renormalization of isoscalar particle-particle interaction strength $g_{pp}^{T=0}$. Using such prescription, the matrix elements $M^{0\nu }$ are evaluated; their values are not very different $\left(\le 20\%\right)$ from the usual QRPA values when $g_{pp}^{T=0}$ is related to the known $2\nu \beta \beta$ half-lives. We note that vanishing values of $M_{cl}^{2\nu }$ are signs of a partial restoration of the spin-isospin SU(4) symmetry.

We formulate the “tensor-optimized high-momentum antisymmetrized molecular dynamics” (TO-HMAMD) framework for ab initio calculations of nuclei by hybridizing the tensor-optimized (TO) and high-momentum (HM) AMD approaches. This hybrid approach has advantages in both analytical simplicity and numerical efficiency compared with other AMD-based methods which treat the bare interaction, especially for heavier nuclear systems. In this work, the $s$-shell nucleus ${}^4\mathrm{He}$ is calculated with TO-HMAMD by including up to double product of nucleon-nucleon ($NN$) correlations, described by using high-momentum pairs and spatial correlation functions of nucleons. The total energy and radius of the ${}^4\mathrm{He}$ nucleus are well reproduced using the $\mathrm{AV}{8}^{\prime }$ interaction. The spin-isospin channel dependence is also discussed for $NN$ correlations, which are found to be mostly contributed in the even-state channels, especially the triplet-even channel. Analyses of the analytical formation and numerical results suggest that TO-HMAMD could be a promising framework for $p$-shell nuclear systems.

We calculate the binding energy of pure neutron matter up to third order in the Brueckner-Bethe-Goldstone hole-line expansion, employing various modern nucleon-nucleon potentials. At that order all results appear well converged to within a few percent up to a density of $0.8{\mathrm{fm}}^{-3}$. We analyze the potentials in terms of the strength of their hard core. Comparison with results of other theoretical methods is made.

The single-particle spectra in relativistic Hartree-Fock (RHF) theory are employed to extract shell correction energies with the Strutinsky method. It is found that proper box sizes $R_{\mathrm{box}}$ used in solving the RHF equations are important to extract reliable Strutinsky shell correction energies. An empirical formula to determine $R_{\mathrm{box}}$ is proposed by systematic studies on nuclei over a wide range of nuclear charts, including light, heavy, neutron-deficient, and neutron-rich nuclei. Furthermore, the shell correction energies of Ca, Pb, and Og isotopes and $N=50$ isotones are calculated with proper $R_{\mathrm{box}}$ and their uncertainties due to the uncertainty of $R_{\mathrm{box}}$ are investigated as well. It is found that the results extracted by the Strutinsky method provide a reliable evaluation of the nuclear shell structure information, which can be employed to construct a macroscopic-microscopic mass model in the future.

We present a generator-coordinate method for realistic shell-model Hamiltonians that closely approximates the full shell model calculations of the matrix elements for the neutrinoless double-$\beta$ decay of ${}^{124}\mathrm{Sn}$, ${}^{130}\mathrm{Te}$, and ${}^{136}\mathrm{Xe}$. We treat not only quadrupole deformations but also the proton-neutron pairing amplitudes as generator coordinates. We validate this method by calculating and comparing spectroscopic quantities with the exact shell model results and experimental data. Our Hamiltonian-based generator-coordinate method produces $0\nu \beta \beta$ matrix elements much closer to the shell model ones, compared to the existing energy-density-functional-based generator-coordinate approaches. The remaining overestimation of $0\nu \beta \beta$ nuclear matrix element suggests that additional correlations may be needed to be taken into account for ${}^{124}\mathrm{Sn}$, ${}^{130}\mathrm{Te}$, and ${}^{136}\mathrm{Xe}$ when calculating with the Hamiltonian-based generator-coordinate method. The validation of this method may open the possibility of calculating $0\nu \beta \beta$ matrix element of ${}^{150}\mathrm{Nd}$ in a large shell-model space.

Background: Quasifission and fusion-fission are primary mechanisms to prevent the production of superheavy elements. The recent experimental measurements reveal that the fusion-evaporation cross section in the $3n$ reaction channel of ${}^{48}\mathrm{Ca}+{}^{239}\mathrm{Pu}$ is 50 times lower than using ${}^{244}\mathrm{Pu}$ as target nucleus [Utyonkov et al., Phys. Rev. C 92, 034609 (2015)]. However, the precise mechanisms of this remarkable isotopic dependence are not well understood.

Purpose: To understand the experimental observation of the rapid decrease of stability of superheavy nuclei as the neutron number decreases, the theoretical studies of quasifission and fusion-fission in connection with experimental production for $Z=114$ flerovium isotopes are required to investigate the possible differences in reaction mechanisms induced by these two targets.

Methods: We propose an approach called TDHF+HIVAP to take into account both the evolution of dinuclear system and the deexcitation of compound nucleus, which combines the microscopic time-dependent Hartree-Fock (TDHF) method for the fusion and quasifission dynamics with the statistical evaporation model HIVAP for fusion-fission dynamics.

Results: Fusion is observed for both reactions ${}^{48}\mathrm{Ca}{+}^{239,244}\mathrm{Pu}$ with the side orientation of the deformed target nucleus, while quasifission dynamics is observed for the tip orientation. The nuclear contact times, masses, and charges as well as the kinetic energies of the fragments, and the mass-angle distribution strongly depend on the colliding energy, impact parameter, and deformation orientation. The quantum shell effect displays a crucial role in both the quasifission and the fusion-fission processes. The quasifission is considerably reduced and the survival probability is enhanced around one order of magnitude in the reaction using ${}^{244}\mathrm{Pu}$ target as compared to the ${}^{239}\mathrm{Pu}$ case.

Conclusions: The studies by using TDHF+HIVAP method well account for the experimental observations and the present method clearly shows its applicability in the reaction mechanisms of quasifission and fusion-fission dynamics. The experimental and theoretical results encourage the use of neutron-rich targets for the production of new superheavy elements.

The problem of analytic continuation of the scattering data to the negative-energy region to obtain information on asymptotic normalization coefficients (ANCs) of bound states is discussed. It is shown that a recently suggested $\mathrm{\Delta }$ method [O. L. Ramírez Suárez and J.-M. Sparenberg, Phys. Rev. C 96, 034601 (2017)] is not strictly correct in the mathematical sense since it is not an analytic continuation of a partial-wave scattering amplitude to the region of negative energies. However, it can be used for practical purposes for sufficiently large charges and masses of colliding particles. Both the $\mathrm{\Delta }$ method and the standard method of continuing of the effective range function are applied to the $p-{}^{16}\mathrm{O}$ system, which is of interest for nuclear astrophysics. The ANCs for the ground $5/2^{+}$ and excited $1/2^{+}$ states of ${}^{17}\mathrm{F}$ are determined.

The electromagnetic transitions of ${}^9\mathrm{Be}$ with linearly polarized $\gamma$ rays are calculated by using the $\alpha +\alpha +n$ three-body model and the complex-scaled solutions of the Lippmann-Schwinger equation; the azimuthal angle distributions of the emitted neutrons are investigated. We calculate the anisotropy parameter as a function of the photon incident energy $E_{\gamma }$ and discuss how sensitive the anisotropy parameter is to nuclear structure and transition modes. The result suggests that the azimuthal angle distribution of neutrons emitted from the ${}^9\mathrm{Be}(\gamma ,n)$ reaction with the linearly polarized $\gamma$ rays is useful to identify the resonances in the final states even if it is not clearly observed in the cross section.

Measured moments of the multiplicity distribution for a given sort of particles are used in the literature for the determination of the phase transition parameters of hot QCD matter in ultrarelativistic heavy-ion collisions. We argue that the subsequent cooling in the hadronic phase, however, may drive the multiplicity distribution out of equilibrium. We use a master equation for the description of the evolution of the multiplicity distribution to demonstrate how the different moments depart away from their equilibrium values. If such moments were measured and interpreted as if they were equilibrated, one would obtain different apparent temperatures from different moments.

In high-energy heavy-ion collisions, the two colliding nuclei pass through each other leaving behind an almost baryon-free central rapidity region. Most of the baryons are carried away by the nuclear remnants and are located in the so-called fragmentation regions. In previous papers [M. Li and J. I. Kapusta, Phys. Rev. C 95, 011901 (2017); arXiv:1808.05751], it has been argued that very high baryon densities, more than ten times larger than the normal nuclear density, can be achieved in these fragmentation regions. In this paper, we assume the high baryon density matter is thermalized at the same time as the baryon-free quark-gluon plasma in the central rapidity region. We perform a 1+1D (temporal + longitudinal) hydrodynamic simulation covering both the fragmentation regions and the central rapidity region with the baryon diffusion equation included. Baryons are found to diffuse from the fragmentation regions to the central rapidity region driven by fugacity gradients. The baryon chemical potential at freezeout monotonically increases from the central rapidity region to the fragmentation regions, suggesting a rapidity scan in high-energy heavy-ion collisions might be helpful in searching for the critical point of the quantum chromodynamics phase diagram.

The Monte Carlo (MC) procedure for sampling the hadron yields within the hadron resonance gas (HRG) model is presented. The effects of excluded volume due to the finite hadron eigenvolumes and of exact charge conservation within the canonical ensemble (CE) formulation are simultaneously taken into account with the help of the importance sampling technique combined with the rejection sampling. The MC procedure allows one to calculate arbitrary moments of the event-by-event hadron yields. Note that the CE formulation for the excluded-volume HRG has not been considered before. The MC simulations coincide with the known analytic results in the thermodynamic limit for the excluded-volume HRG in the grand canonical ensemble and for the CE of noninteracting particles. The MC procedure is applied to study the simultaneous excluded-volume and CE effects. These effects are considered within the full HRG to calculate the particle number fluctuations and to estimate the finite-size effects.

Longitudinal phase space analyses as introduced by van Hove provided a simplified method of separating different reaction production mechanisms. Cuts in the longitudinal phase space can help to select specific reaction kinematics but also induce nonflat acceptance effects in angular distributions. We show that in photoproduction reactions dominated by $t$-channel exchanges, selection of meson or baryon production over a large mass range can be optimized through calculating mass-dependent cut limits compared to cuts on a van Hove plot sector alone. A cut is presented that improves this selection of one type of hadron production by rejecting another. In addition we demonstrate that using cuts in longitudinal phase space preserves sufficient information to reliably extract observables from the angular distribution of the final state particles.

The medium modifications of the masses of the charmonium states $[J/\psi$, $\psi$(3686), and $\psi$(3770)] in asymmetric nuclear matter in the presence of strong magnetic fields are studied using an effective chiral model. The mass modifications arise due to medium modifications of the scalar dilaton field, which simulates the gluon condensates of QCD within the effective hadronic model. The effects due to the magnetic field as well as isospin asymmetry are observed to be appreciable at high densities for the charmonium states, which can have consequences, e.g., in the production of the open charm mesons and the charmonium states, in asymmetric heavy ion collisions in compressed baryonic matter (CBM) experiments at the future facility at GSI. The presence of the magnetic field leads to Landau quantization of the energy levels of the proton in the asymmetric nuclear matter. The effects of the anomalous magnetic moments of the proton and neutron on the masses of the charmonium states are studied and are observed to lead to larger masses of the charmonium states, as compared to when these effects are not taken into account.

We study the strangeness $S=-2$ baryon-baryon interactions in relativistic chiral effective field theory at leading order. Among the 15 relevant low-energy constants, 8 of them are determined by fitting to the state of the art lattice QCD data of the HAL QCD Collaboration (with $m_{\pi }=146$ MeV), and the rest either are taken from the study of the $S=-1$ hyperon-nucleon systems, assuming strict SU(3) flavor symmetry, or are temporarily set equal to zero. Using the so-obtained low-energy constants, we extrapolate the results to the physical point and show that they are consistent with the available experimental scattering data. Furthermore, we demonstrate that the $\mathrm{\Lambda }\mathrm{\Lambda }$ and $\mathrm{\Xi }N$ phase shifts near the $\mathrm{\Xi }N$ threshold are very sensitive to the lattice QCD data fitted, to the pion mass, and to isospin symmetry-breaking effects. As a result, any conclusion drawn from lattice QCD data at unphysical pion masses (even close to the physical point) should be taken with caution. Our results at the physical point, similar to the lattice QCD data, show that a resonance (quasibound state) may appear in the $I=0$ $\mathrm{\Lambda }\mathrm{\Lambda }$ ($\mathrm{\Xi }N$) channel.

We quantify the theoretical uncertainties of chiral effective-field-theory predictions of the muon-deuteron capture rate. Theoretical error estimates of this low-energy process are important for a reliable interpretation of forthcoming experimental results by the MuSun Collaboration. Specifically, we estimate the three dominant sources of uncertainties that impact theoretical calculations of this rate: those resulting from uncertainties in the pool of fit data used to constrain the coupling constants in the nuclear interaction, those due to the truncation of the effective field theory, and those due to uncertainties in the axial radius of the nucleon. For the capture rate into the ${}^{1}S_0$ channel, we find an uncertainty of approximately $4.6{\mathrm{s}}^{-1}$ due to the truncation in the effective field theory and an uncertainty of $3.9{\mathrm{s}}^{-1}$ due to the uncertainty in the axial radius of the nucleon, both of which are similar in size to the targeted experimental precision of a few percent.

We investigate the constraints on the mass and radius of neutron stars by considering the tidal deformability in the merge of neutron star binaries. We employ models based on the Skyrme force and density-functional theory and select models that are consistent with empirical data of finite nuclei, measured properties of nuclear matter around the saturation density, and observation of the maximum mass of neutron stars. From the selected models, we calculate the Love number $k_2$, dimensionless tidal deformability $\mathrm{\Lambda }$, and mass-weighted deformability $\tilde{\mathrm{\Lambda }}$ in the binary system. We find that all the models considered in this work give $\tilde{\mathrm{\Lambda }}$ less than 800, which is the constraint obtained from the measurement of GW170817. The results from our models show a relationship between $\mathrm{\Lambda }$ and radius ($\mathrm{\Lambda }\sim R^{7.5}$) for a neutron star with a fixed mass of $1.4M_{\odot }$, which is consistent with the recent statistical analyses.

The seniority symmetry is known to be partially conserved in two special cases in the ${(9/2)}^4$ system, which can lead to striking features in the corresponding structure and electromagnetic transition properties. However, it is still quite difficult to derive those kind of solvable states, in general, especially towards higher-$j$ orbits. We have developed a novel and effective way to confront this challenge by starting from the $m$ scheme and making use of the angular momentum projection method. It also allows us to explore another special family of seniority conserving states in the midshell besides the specific case of the ${(9/2)}^4$ configuration. Moreover, we have studied systemically all states in single-$j$ systems up to $j=15/2$ and derived the analytic expressions for the eigenvalues of all solvable states with a focus on those in $j=9/2$ and $j=11/2$. Such studies can also be useful for the experimental search of relevant states and for the understanding of their electromagnetic transition properties.

The collective harmonic flow in heavy-ion collisions correlates particles at all transverse momenta to be emitted preferably along some directions. The factorization breaking coefficient measures the small decorrelation of the flow harmonics at two different transverse momenta. Using the hydrodynamic model I study in detail the factorization breaking of the harmonic flow due to the flow angle decorrelation and the flow magnitude decorrelation at two transverse momenta. The effect can be seen in experiment measuring factorization breaking coefficients for the square of the harmonic flow vector at two transverse momenta. The hydrodynamic model predicts that the decorrelation of the flow magnitudes is about one-half of the decorrelation of the overall flow (combining flow angle and flow magnitude decorrelations). These results are qualitatively consistent with the principal component analysis of correlators of flow vectors squared.