Multifragmentation scenarios, as predicted by antisymmetrized molecular dynamics (AMD) or momentum-dependent stochastic mean-field (BGBD) calculations are compared. Whereas in the BGBD case fragment emission is clearly linked to the spinodal decomposition mechanism (i.e., to mean-field instabilities), in AMD many-body correlations have a stronger impact on the fragmentation dynamics. In fact, the density and momentum fluctuations develop earlier in AMD, suggesting that fragments are formed on shorter time scales in AMD, on about equal footing as light-particle pre-equilibrium emission.

High precision quasi-elastic scattering excitation functions have been measured at energies well below the Coulomb barrier for the reactions of ${}^{32}\mathrm{S}$ with ${}^{208}\mathrm{Pb}$, ${}^{197}\mathrm{Au}$, ${}^{186}\mathrm{W}$, and ${}^{170}\mathrm{Er}$. Single-channel and coupled-channels calculations have been performed to extract the diffuseness parameter of the nuclear potential. For the reactions involving near-spherical targets, both theoretical analyses give the same diffuseness parameter. On the other hand, for deformed systems, couplings are important even at deep sub-barrier energies. In general, the effect of couplings is to reduce the diffuseness parameter value extracted from a single-channel potential. Single-channel fits to quasi-elastic scattering data result in $a=0.72\text{−}0.82$ fm, whereas coupled-channels calculations give diffuseness parameters in the range 0.58–0.75 fm.

We investigate fully nonlinear, non-Abelian excitations of quark-antiquark plasma using relativistic fluid theory in cold plasma approximation. There are mainly three important nonlinearities, coming from various sources such as non-Abelian interactions of Yang-Mills (YM) fields, Wong's color dynamics, and plasma nonlinearity, in our model. By neglecting nonlinearities due to plasma and color dynamics we obtain the earlier results of J. P. Blaizot and E. Iancu [Phys. Rev. Lett. 72, 3317 (1994)]. Similarly, by neglecting YM field nonlinearity and plasma nonlinearity, the model reduces to the model of S. S. Gupta, P. K. Kaw, and J. C. Parikh [Phys. Lett. B498, 223 (2005)]. Thus we have the most general non-Abelian mode of quark-gluon plasma. Further, our model resembles the model of laser propagation through relativistic plasma [P. K. Paw, A. Sen, and E. J. Valeo, Physica 9D, 96 (1983)] in the absence of all non-Abelian interactions.

Results from electric charge correlations studied with the Balance Function (BF) method in $A+A$ collisions from $20A$ to $158A$ GeV are presented in two different rapidity intervals: In the midrapidity region we observe a decrease of the width of the BF distribution with increasing centrality of the collision, whereas this effect vanishes in the forward rapidity region. Results from the energy dependence study in central $\mathrm{Pb}+\mathrm{Pb}$ collisions show that the narrowing of the BF expressed by the normalized width parameter $W$ increases with energy toward the highest CERN Super Proton Synchrotron and BNL Relativistic Heavy Ion Collider energies. Finally we compare our experimental data points with the predictions of several models. The hadronic string models Ultra-relativistic Quantum Molecular Dynamics and Heavy Ion Jet INteraction Generator (HIJING) do not reproduce the observed narrowing of the BF. However, A MultiPhase Transport medel (AMPT), which contains a quark-parton transport phase before hadronization, can reproduce the narrowing of the BF's width with centrality. This confirms the proposed sensitivity of the BF analysis to the time of hadronization.

We present a new approach for calculating the nuclear equation of state and compressibility for finite nuclei using the density-constrained Hartree-Fock method.

${\pi }^{+}$ and ${\pi }^{-}$ elastic and inelastic scattering to the $2_1^{+}$(4.44 MeV) state on ${}^{12}\mathrm{C}$ at 995 MeV/$c$ were measured over an angular range for elastic-scattering from ${5.4}^{°}$ to ${28.2}^{°}$ and for inelastic scattering from ${15.2}^{°}$ to ${22.8}^{°}$. Both of the elastic-scattering data sets were well reproduced by first-order factorized momentum-space optical potential calculations with free π-$N$ elementary amplitudes and three different ground state densities, which were deduced from the charge density and microscopic model calculations, the cluster model and the shell model. We also extracted ${\sigma }_{\mathrm{tot}},{\sigma }_{\mathrm{el}}$, and ${\sigma }_R$ phenomenologically and compared them with a Fermi averaging model. The inelastic cross sections of ${\pi }^{+}$-${}^{12}\mathrm{C}$ and ${\pi }^{-}$-${}^{12}\mathrm{C}$ were compared with the DWIA calculations, one using the transition density($0^{+}\to 2_1^{+}$) deduced by the cluster model and the other using the transition density deduced by the shell model.

To describe momentum isotropization of gluon matter produced in ultrarelativistic heavy-ion collisions, the transport rate of gluon drift and the transport collision rates of elastic ($\mathit{gg}\leftrightarrow \mathit{gg}$) as well as inelastic ($\mathit{gg}\leftrightarrow \mathrm{ggg}$) perturbative quantum chromodynamics- (pQCD) scattering processes are introduced and calculated within the kinetic parton cascade Boltzmann approach of multiparton scatterings (BAMPS), which simulates the space-time evolution of partons. We define isotropization as the development of an anisotropic system as it reaches isotropy. The inverse of the introduced total transport rate gives the correct time scale of the momentum isotropization. The contributions of the various scattering processes to the momentum isotropization can be separated into the transport collision rates. In contrast to the transport cross section, the transport collision rate has an indirect but correctly implemented relationship with the collision-angle distribution. Based on the calculated transport collision rates from BAMPS for central Au+Au collisions at Relativistic Heavy Ion Collider energies, we show that pQCD $\mathit{gg}\leftrightarrow \mathrm{ggg}$ bremsstrahlung processes isotropize the momentum five times more efficiently than elastic scatterings. The large efficiency of the bremsstrahlung stems mainly from its large momentum deflection. Due to kinematics, $2\to N$ $(N>2)$ production processes allow more particles to become isotropic in momentum space and thus kinetically equilibrate more quickly than their back reactions or elastic scatterings. We also show that the relaxation time in the relaxation time approximation, which is often used, is strongly momentum dependent and thus cannot serve as a global quantity that describes kinetic equilibration.

The implications of parton recombination processes on the dynamics of ultrarelativistic heavy-ion reactions are investigated. To do so, the quark-gluon string transport model has been extended for partonic recombination and fusion processes. Parton recombination leads to short equilibration times and improves significantly on the theoretical description of measured directed and elliptic flow, i.e., $v_1$ and $v_2$, distributions in Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=200\mathrm{GeV}$, in particular what concerns their pseudorapidity dependence. The shape of $v_2(\eta )$ is found to be closely related to fast thermalization.

Differential cross sections for the reaction $\gamma p\to p{\pi }^0$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.675 to 2.875 GeV. The results reported here possess greater accuracy in the absolute normalization than previous measurements. They disagree with recent CB-ELSA measurements for the process at forward scattering angles. Agreement with the SAID and MAID fits is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been extended to 3 GeV. Resonance couplings have been extracted and compared to previous determinations.

Four long-lived neutron-deficient Th isotopes with atomic mass numbers 211 to 218 and abundances of ($1–10$)$\times {10}^{-11}$ relative to ${}^{232}\mathrm{Th}$ have been found in a study of naturally-occurring Th using inductively coupled plasma-sector field mass spectrometry. It is deduced that long-lived isomeric states exist in these isotopes. The hypothesis that they might belong to a new class of long-lived high spin super- and hyperdeformed isomeric states is discussed.

Isospin effect of the statistical emission fragments from the equilibrated source is investigated in the frame of statistical binary decay implemented into the GEMINI code, isoscaling behavior is observed and the dependences of isoscaling parameters α and β on emission fragment size, source size, source isospin asymmetry and excitation energies are studied. Results show that α and β neither depends on light fragment size nor on source size. A good linear dependence of α and β on the inverse of temperature $T$ is manifested and the relationship of $\alpha =4C_{\mathrm{sym}}[(Z_s/A_s){}_1^2-(Z_s/A_s){}_2^2]/T$ and $\beta =4C_{\mathrm{sym}}[(N_s/A_s){}_1^2-(N_s/A_s){}_2^2]/T$ from different isospin asymmetry sources is satisfied. The symmetry energy coefficient $C_{\mathrm{sym}}$ extracted from simulation results is ∼ 23 MeV which includes both the volume and surface term contributions, of which the surface effect seems to play a significant role in the symmetry energy.

Various measurements of the Coulomb breakup of ${}^8\mathrm{B}$ are analyzed within the dynamical eikonal approximation using a single description of ${}^8\mathrm{B}$. We obtain a good agreement with experiment for different observables measured between 40 and 80 MeV/nucleon. A simple ${}^7\mathrm{Be}$-$p$ potential model description of ${}^8\mathrm{B}$ seems sufficient to describe all observables. In particular, the asymmetry in parallel-momentum distributions due to $E1\text{−}E2$ interferences is well reproduced without any scaling. The projectile-target nuclear interactions seem negligible if data are selected at forward angles. On the contrary, like in previous analyses we observe a significant influence of higher-order effects. The accuracy of astrophysical $S$ factors for the ${}^7\mathrm{Be}$($p,\gamma$)${}^8\mathrm{B}$ reaction at stellar energies extracted from breakup measurements therefore seems difficult to evaluate.

The equilibration of macroscopic degrees of freedom during the fusion of heavy nuclei, such as the charge and the shape, are studied in the time-dependent Hartree-Fock theory. The preequilibrium giant dipole resonance (GDR) is used to probe the fusion path. It is shown that such an isovector collective state is excited in $N/Z$ asymmetric fusion and to a lesser extent in mass asymmetric systems. The characteristics of this GDR, such as its deformation, rotation, and vibration, are governed by the structure of the fused system in its preequilibrium phase. In particular, we show that a loweringq of the preequilibrium GDR energy is expected as compared to the statistical one. Revisiting experimental data, we extract evidence of this lowering for the first time. We also quantify the fusion-evaporation enhancement resulting from γ-ray emission from the preequilibrium GDR. This cooling mechanism along the fusion path may be suitable for synthesizing in the future superheavy elements using radioactive beams with strong $N/Z$ asymmetries in the entrance channel.

In peripheral collisions of relativistic heavy ions highly excited spectators containing Λ hyperons can be produced. Such strange spectator matter may undergo a break-up into many fragments (multifragmentation) as it is well established for ordinary nuclear systems. We generalize the statistical multifragmentation model, previously successfully used for the description of experimental data, for the case of hypernuclear systems. We predict relative yields of hypernuclei and the main characteristics of such a breakup. We point at a connection of this phenomenon with a liquid-gas phase transition in hypermatter.

We study entropy production in the early stage of high-energy heavy-ion collisions due to shear viscosity. We employ the second-order theory of Israel-Stewart with two different stress relaxation times, as appropriate for strong coupling or for a Boltzmann gas, respectively, and compare the hydrodynamic evolution. Based on the present knowledge of initial particle production, we argue that entropy production is tightly constrained. We derive new limits on the shear viscosity to entropy density ratio $\eta /s$, independent from elliptic flow effects, and determine the corresponding Reynolds number. Furthermore, we show that for a given entropy production bound, the initial time ${\tau }_0$ for hydrodynamics is correlated to the viscosity. The conjectured lower bound for $\eta /s$ provides a lower limit for ${\tau }_0$.

The α-decay half-lives of the exotic $N=125$, 126, and 127 isotones (Po, Rn, Ra, Th, and U) are systematically studied by the density-dependent cluster model (DDCM). The influence of the neutron shell closure $N=126$ on the α-cluster formation and penetration probabilities is analyzed and discussed in detail. By combining the DDCM and a two-level microscopic model together, the experimental half-lives of α transitions to both the ground state and the excited state in the daughter nuclei are reproduced very well.

The spectrum of ${}^9\mathrm{He}$ was studied by means of the ${}^2\mathrm{H}$(${}^8\mathrm{He}$,$p$)${}^9\mathrm{He}$ reaction at a laboratory energy of 25 MeV/nucleon and small center-of-mass angles. Energy and angular correlations were obtained for the ${}^9\mathrm{He}$ decay products by complete kinematical reconstruction. The lowest resonant state of ${}^9\mathrm{He}$ is found at 2.0 ± 0.2 MeV with a width of $~2$ MeV and is identified as $1/2^{-}$. The observed angular correlation pattern is uniquely explained by the interference of the $1/2^{-}$ resonance with a virtual $1/2^{+}$ state (a limit $a>-20$ fm is obtained for the scattering length), and with a $5/2^{+}$ resonance at energy $⩾4.2$ MeV.

Nuclear matrix elements of the neutrinoless double beta ($0\nu \beta \beta$) decays of ${}^{96}\mathrm{Zr}$, ${}^{100}\mathrm{Mo}$, ${}^{116}\mathrm{Cd}$, ${}^{128}\mathrm{Te}$, ${}^{130}\mathrm{Te}$, and ${}^{136}\mathrm{Xe}$ are calculated for the light-neutrino exchange mechanism by using the proton-neutron quasiparticle random-phase approximation (pnQRPA) with a realistic nucleon-nucleon force. The particle-particle strength parameter $g_{\mathrm{pp}}$ of the pnQRPA is fixed by the data on the two-neutrino double β and single β decays. The finite size of a nucleon, the higher-order terms of nucleonic weak currents, and the nucleon-nucleon short-range correlations (s.r.c) are taken into account. The s.r.c. are computed by the traditional Jastrow method and by the more advanced unitary correlation operator method (UCOM). A comparison of the results obtained by the two methods reveals that the UCOM computed matrix elements are considerably larger than the Jastrow computed ones. This result is important to the assessment of the neutrino-mass sensitivity of present and future double β experiments.

Incorporation of the finite size of baryons into the equation of state (EOS) of a hot and dense hadron gas (HG) in a thermodynamically consistent manner has been a much studied problem. We first review its current status. Various models have been proposed in order to account for the repulsive force generated by the hard-core geometrical size of the baryons resulting in an excluded volume effect in the EOS. We examine the criterion of the thermodynamical consistency of these models and summarize their shortcomings. In order to remove the shortcomings, we propose a new model which incorporates the excluded volume effect in a thermodynamically consistent manner. We find that the new model works even for the cases of extremely large temperatures and densities where most of other approaches fail. Furthermore, the new expressions for thermodynamical variables resemble in form with those obtained from thermodynamically inconsistent models and thus a useful correction factor has been suggested here which converts inconsistent expressions into thermodynamically consistent ones. Finally we compare the predictions of new model with those obtained from various old models.

The lifetime of the $2_1^{+}$ state at 1256.7 keV in ${}^{112}\mathrm{Sn}$ has been determined using the ($n$,$n^{\text{'}}\gamma$) reaction. Angular distribution measurements were carried out at a neutron energy of 1.7 MeV, above the $2_1^{+}$ energy threshold and below that of the second excited level. Through the Doppler-shift attenuation method, the lifetime of the $2_1^{+}$ state is determined as ${750}_{-90}^{+125}$ fs, which gives a $B(E2;2_1^{+}\to 0_1^{+})$ value of ${10.9}_{-1.6}^{+1.5}$ W.u. This $E2$ strength in ${}^{112}\mathrm{Sn}$ also allows a redetermination of the $B(E2;2_1^{+}\to 0_1^{+})$ in ${}^{108}\mathrm{Sn}$ as 10.8(3.0) W.u. These values result in a symmetric trend around the neutron midshell in the systematics of $E2$ strengths in the even-mass tin isotopes and do not support $N=64$ or $N=66$ subshell gaps. The symmetric trend is in agreement with recent shell model predictions, where proton-core excitations were allowed in the calculations.