A statistical theory of light nucleus reactions (STLN) is proposed to describe both neutron and light charged particle induced nuclear reactions with $1p\text{-shell}$ light nuclei involved. The dynamics of STLN is described by the unified Hauser-Feshbach and exciton model, in which the angular momentum and parity conservations are strictly considered in equilibrium and pre-equilibrium processes. The Coulomb barriers of the incoming and outgoing charged particles, which significantly influence the open channels of the reaction, can be reasonably considered in the incident channel and different outgoing channels. In kinematics, the recoiling effects in various emission processes are strictly taken into account. The analytical double-differential cross sections of the reaction products in sequential and simultaneous emission processes are obtained in terms of the new integral formula proposed in our recent paper [Phys. Rev. C 92, 061601(R) (2015)]. Taking the ${}^9\text{Be}(p,xn)$ reaction as an example, we calculate the double-differential cross sections of outgoing neutrons and charged particles using the punf code in the frame of STLN. The existing experimental double-differential cross sections of neutrons at $E_p=18$ MeV can be remarkably well reproduced, which indicates that the punf code is a powerful tool to set up “file-6” in the reaction data library for light charged particle induced nuclear reactions with $1p\text{-shell}$ light nuclei involved.

We develop a flexible quasiparticle theory of transport coefficients of hot hadronic matter at finite baryon density. We begin with a hadronic quasiparticle model which includes a scalar and a vector mean field. Quasiparticle energies and the mean fields depend on temperature and baryon chemical potential. Starting with the quasiparticle dispersion relation, we derive the Boltzmann equation and use the Chapman-Enskog expansion to derive formulas for the shear and bulk viscosities and thermal conductivity. We obtain both relaxation-time approximation formulas and more general integral equations. Throughout the work, we explicitly enforce the Landau-Lifshitz conditions of fit and ensure the theory is thermodynamically self-consistent. The derived formulas should be useful for predicting the transport coefficients of the hadronic phase of matter produced in heavy-ion collisions at the Relativistic Heavy Ion Collider and at other accelerators.

We present measurements of $e^{+}{e}^{-}$ production at midrapidity in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass ($m_{ee}<5 \mathrm{GeV}/c^2$) and pair transverse momentum ($p_T<5 \mathrm{GeV}/c$) for minimum bias and for five centrality classes. The $e^{+}{e}^{-}$ yield is compared to the expectations from known sources. In the low-mass region ($m_{ee}=0.30–0.76 \mathrm{GeV}/c^2$) there is an enhancement that increases with centrality and is distributed over the entire pair $p_T$ range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to $2.3\pm 0.4\left(\mathrm{stat}\right)\pm 0.4\left(\mathrm{syst}\right)\pm 0.2\left(\mathrm{model}\right)$ or to $1.7\pm 0.3\left(\mathrm{stat}\right)\pm 0.3\left(\mathrm{syst}\right)\pm 0.2\left(\mathrm{model}\right)$ for minimum bias collisions when the open heavy-flavor contribution is calculated with pythia or mc@nlo, respectively. The inclusive mass and $p_T$ distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the $\rho$ meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region ($m_{ee}=1.2–2.8 \mathrm{GeV}/c^2$), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.

Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory and accounts for cancellations between the contributions of irreducible diagrams and the contributions owing to nonstatic corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and conserved in the chiral limit, while the axial charge requires renormalization. A complete set of contact terms for the axial charge up to the relevant order in the power counting is constructed.

We apply the generator coordinate method (GCM) to single-$\mathrm{\Lambda }$ hypernuclei in order to discuss the spectra of hypernuclear low-lying states. To this end, we use the same relativistic point-coupling energy functional both for the mean-field and the beyond-mean-field calculations. This relativistic GCM approach provides a unified description of low-lying states in ordinary nuclei and in hypernuclei, and is thus suitable for studying the $\mathrm{\Lambda }$ impurity effect. We carry out an illustrative calculation for the low-lying spectrum of ${}_{\mathrm{\Lambda }}{}^{21}\mathrm{Ne}$, in which the interplay between the hypernuclear collective excitations and the single-particle excitations of the unpaired $\mathrm{\Lambda }$ hyperon is taken into account in a full microscopic manner.

The dependence of correlations of neutron multiplicity $\nu$ and $\gamma$-ray multiplicity $M_{\gamma }$ in spontaneous fission of ${}^{252}\mathrm{Cf}$ on fragment mass $A^{*}$ and total kinetic energy (TKE) have been investigated by employing the ratio of $M_{\gamma }/\nu$ and the form of $M_{\gamma }\left(\nu \right)$. We show for the first time that $M_{\gamma }$ and $\nu$ have a complex correlation for heavy fragment masses, while there is a positive dependence of $M_{\gamma }$ for light fragment masses and for near-symmetric mass splits. The ratio $M_{\gamma }/\nu$ exhibits strong shell effects for neutron magic number $N=50$ and near doubly magic number shell closure at $Z=50$ and $N=82$. The $\gamma$-ray multiplicity $M_{\gamma }$ has a maximum for $\text{TKE}=165–170$ MeV. Above 170 MeV $M_{\gamma }$(TKE) is approximately linear, while it deviates significantly from a linear dependence at lower TKE. The correlation between the average neutron and $\gamma$-ray multiplicities can be partly reproduced by model calculations.

We comment on a recently published paper by R. Wolski entitled “Compound nucleus aspect of sub-barrier fusion: A new energy scaling behavior” [1], which claims that the sub-barrier fusion is determined mostly by the $Q$ value of the compound nucleus formation. This ignores the dynamical channel-coupling effects at near-barrier energies. We demonstrate that this simplified scaling of fusion cross sections is not a common case and has no predictive power.

Excited states with seniority $\nu =3$, 5, and 7 have been investigated in odd neutron-rich ${}^{119,121,123,125}\text{Sn}$ isotopes produced by fusion-fission of 6.9-MeV/$A{}^{48}\text{Ca}$ beams with ${}^{208}\text{Pb}$ and ${}^{238}\text{U}$ targets and by fission of a ${}^{238}\text{U}$ target bombarded with 6.7-MeV/$A{}^{64}\text{Ni}$ beams. Level schemes have been established up to high spin and excitation energies in excess of 6 MeV, based on multifold gamma-ray coincidence relationships measured with the Gammasphere array. In the analysis, the presence of isomers was exploited to identify gamma rays and propose transition placements using prompt and delayed coincidence techniques. Gamma decays of the known $27/2^{-}$ isomers were expanded by identifying new deexcitation paths feeding $23/2^{+}$ long-lived states and $21/2^{+}$ levels. Competing branches in the decay of $23/2^{-}$ states toward two $19/2^{-}$ levels were delineated as well. In ${}^{119}\text{Sn}$, a new $23/2^{+}$ isomer was identified, while a similar $23/2^{+}$ long-lived state, proposed earlier in ${}^{121}\text{Sn}$, has now been confirmed. In both cases, isomeric half-lives were determined with good precision. In the range of $\nu =3$ excitations, the observed transitions linking the various states enabled one to propose with confidence spin-parity assignments for all the observed states. Above the $27/2^{-}$ isomers, an elaborate structure of negative-parity levels was established reaching the ($39/2^{-}$), $\nu =7$ states, with tentative spin-parity assignments based on the observed deexcitation paths as well as on general yrast population arguments. In all the isotopes under investigation, strongly populated sequences of positive-parity ($35/2^{+}$), ($31/2^{+}$), and ($27/2^{+}$) states were established, feeding the $23/2^{+}$ isomers via cascades of three transitions. In the ${}^{121,123}\text{Sn}$ isotopes, these sequences also enabled the delineation of higher-lying levels, up to ($43/2^{+}$) states. In ${}^{123}\text{Sn}$, a short half-life was determined for the ($35/2^{+}$) state. Shell-model calculations were carried out for all the odd Sn isotopes, from ${}^{129}\text{Sn}$ down to ${}^{119}\text{Sn}$, and the results were found to reproduce the experimental level energies rather well. Nevertheless, some systematic deviations between calculated and experimental energies, especially for positive-parity states, point to the need to improve some of the two-body interactions used in calculations. The computed wave-function amplitudes provide for a fairly transparent interpretation of the observed level structures. The systematics of level energies over the broad $A$ = 117–129 range of Sn isotopes displays a smooth decrease with mass $A$, and the observed regularity confirms most of the proposed spin-parity assignments. The systematics of the $B\left(E2\right)$ reduced transition probabilities extracted for the $23/2^{+}$ and $19/2^{+}$ isomers is discussed with an emphasis on the close similarity of the observed $A$ dependence with that of the $E2$ transition rates established for other $\nu =2$, 3, and 4 isomers in the Sn isotopic chain.

The reaction $ep\to e^{\prime }{K}^{+}{\mathrm{\Sigma }}^0$ has been investigated using a tree-level effective Lagrangian model previously employed by the author to study the $\gamma p\to K^{+}{\mathrm{\Sigma }}^0$ reaction. In addition to the Born terms, the model incorporates a number of baryon resonances with spins up to $\frac{5}{2}$ and the two kaon resonances, $K^{☆}\left(892\right)$ and $K1\left(1270\right)$. Momentum and energy dependent widths for the nucleon and $\mathrm{\Delta }$ resonances are included by means of a dynamical model that makes use of empirical on-shell branching ratios. The model parameters are fit to a large pool of photoproduction data from the CLAS and GRAAL collaborations and electroproduction data from the CLAS collaboration. Photoproduction results are presented for the unpolarized differential cross section, the photon beam asymmetry $\mathrm{\Sigma }$, the hyperon recoil asymmetry $P$, and the double polarization observables $C_x$ and $C_z$. Electroproduction results are presented for the virtual photoproduction structure functions ${\sigma }_U, {\sigma }_{TT}, {\sigma }_{LT}$, and ${\sigma }_{L{T}^{\prime }}$. The photoproduction results are compared with the CLAS and GRAAL photoproduction data and with the results of an earlier fit to just the photoproduction data, while the electroproduction results are compared with both recent and older CLAS electroproduction data.

Within a mean-field approximation, we study a nontopological soliton solution of the Polyakov quark-meson model in the presence of a fermionic vacuum term with two flavors at finite temperature and density. The profile of the effective potential exhibits a stable soliton solution below a critical temperature $T\le T_{\chi }^c$ for both the crossover and the first-order phase transitions, and these solutions are calculated here with appropriate boundary conditions. However, it is found that only if $T\le T_d^c$ is the energy of the soliton $M_N$ less than the energy of the three free constituent quarks $3M_q$. As $T>T_d^c$, there is an instant delocalization phase transition from hadron matter to quark matter. The phase diagram together with the location of a critical end point has been obtained in the $T$ and $\mu$ plane. We notice that two critical temperatures always satisfy $T_d^c\le T_{\chi }^c$. Finally, we present and compare the result of thermodynamic pressure at zero chemical potential with lattice data.

Background: Traditionally, nucleon-nucleus optical potentials are made local for convenience. In recent work we studied the effects of including nonlocal interactions explicitly in the final state for $(d,p)$ reactions, within the distorted wave Born approximation.

Purpose: Our goal in this work is to develop an improved formalism for nonlocal interactions that includes deuteron breakup and to use it to study the effects of including nonlocal interactions in transfer $(d,p)$ reactions, in both the deuteron and the proton channel.

Method: We extend the finite-range adiabatic distorted wave approximation to include nonlocal nucleon optical potentials. We apply our method to $(d,p)$ reactions on ${}^{16}\mathrm{O}$, ${}^{40}\mathrm{Ca}$, ${}^{48}\mathrm{Ca}$, ${}^{126}\mathrm{Sn}$, ${}^{132}\mathrm{Sn}$, and ${}^{208}\mathrm{Pb}$ at 10, 20, and 50 MeV.

Results: We find that nonlocality in the deuteron scattering state reduces the amplitude of the wave function in the nuclear interior, and shifts the wave function outward. In many cases, this has the effect of increasing the transfer cross section at the first peak of the angular distributions. This increase was most significant for heavy targets and for reactions at high energies.

Conclusions: Our systematic study shows that, if only local optical potentials are used in the analysis of experimental $(d,p)$ transfer cross sections, the extracted spectroscopic factors may be incorrect by up to $40\%$ due to the local approximation.

The distribution of the electromagnetic dipole strength below the neutron separation energy and its influence on the photon distribution after neutron capture were investigated in two experiments for the compound nucleus ${}^{114}\mathrm{Cd}$. By measuring the photoabsorption cross section at the bremsstrahlung facility $\gamma \mathrm{ELBE}$ at Helmholtz-Zentrum Dresden-Rossendorf it was possible to deduce the distribution of dipole strength below the neutron separation energy. The de-excitation spectrum after cold-neutron capture in ${}^{113}\mathrm{Cd}$ was measured at the Budapest Neutron Center. In a combined analysis, the experimentally deduced spectra after photon scattering on ${}^{114}\mathrm{Cd}$ and the neutron capture in ${}^{113}\mathrm{Cd}$ were analyzed in terms of electric and magnetic strength functions and nuclear level density with the help of the statistical code $\gamma$dex.

The shell corrections and shell gaps in nuclei are systematically studied with the latest Weizsäcker-Skyrme (WS4) mass model. We find that most of asymmetric nuclei with (sub)shell closures locate along the shell stability line (SSL), $N=1.37Z+13.5$, which might be due to a strong correlation between neutrons and protons near the Fermi surface. The double magicity of nuclei ${}^{46}\mathrm{Si}$ and ${}^{78}\mathrm{Ni}$ is predicted according to the corresponding shell gaps, shell corrections, and nuclear deformations. The unmeasured superheavy nuclei, ${}^{296}118$ and ${}^{298}120$, with relatively large shell gaps and shell corrections, also locate along the SSL, whereas the traditional magic nucleus ${}^{298}\mathrm{Fl}$ evidently deviates from the line. The $\alpha$-decay energies of superheavy nuclei with $Z=113\text{–}126$ are simultaneously investigated by using the WS4 model together with the radial basis function corrections. For superheavy nuclei with large shell corrections, the smallest $\alpha$-decay energy for elements $Z=116$, 117, and 118 in their isotope chains locates at $N=178$ rather than 184.

It is generally considered that an atomic nucleus is always compact. Based on the isospin-dependent Boltzmann nuclear transport model, here I show that large block nuclear matter or excited nuclear matter may both be hollow. The size of the inner bubble in these matter is affected by the charge number of nuclear matter. The existence of hollow nuclear matter may have many implications in nuclear or atomic physics or astrophysics as well as some practical applications.

The collective clusterization approach of the dynamical cluster decay model (DCM) has been applied to study the decay of odd mass nuclei ${}^{215}\text{Fr}^{*},{}^{223}\text{Pa}^{*},{}^{227}\text{Np}^{*}$, and ${}^{233}\text{Am}^{*}$, which are formed in heavy-ion-induced reactions. The aim of this study is to investigate the decay pattern and related behavior of these heavy mass nuclei formed in four distinct reactions involving different projectiles (with mass $A=18\text{–}36$) induced on ${}^{197}\text{Au}$ target nucleus. Further, in order to analyze the role of deformations, the calculations have been done by considering spherical choice of fragmentation as well as with inclusion of quadrupole $\left({\beta }_2\right)$ deformation. For the heavy mass region, with fission being the dominant decay mode, an attempt has been made to investigate the effect of projectile mass in reference to fission decay patterns of the pre-actinide ${}^{215}\text{Fr}^{*}$ nucleus and the trans-actinide nuclei ${}^{223}\text{Pa}^{*},{}^{227}\text{Np}^{*}$, and ${}^{233}\text{Am}^{*}$ formed at common excitation energy, $E_{CN}^{*}=60\mathrm{MeV}$. Besides this, the shell closure effects and the role of orientation have been explored, which suggest the presence of a noncompound nucleus process such as quasifission (QF) for the odd mass nuclei under consideration. For both the compound nucleus and the noncompound nucleus processes, the results obtained using DCM are found to have nice agreement with experimental observations. The isotopic and isobaric analysis is also worked out so as to have a comprehensive idea about the dynamics involved.

We implement a Langevin approach for the transport of heavy quarks in the ultrarelativistic quantum molecular dynamics (UrQMD) hybrid model, which uses the transport model UrQMD to determine realistic initial conditions for the hydrodynamical evolution of quark gluon plasma and heavy charm and bottom quarks. It provides a realistic description of the background medium for the evolution of relativistic heavy ion collisions. The diffusion of heavy quarks is simulated with a relativistic Langevin approach, using two sets of drag and diffusion coefficients, one based on a $T$-matrix approach and one based on a resonance model for elastic scattering of heavy quarks within the medium. In the case of the resonance model we investigate the effects of different decoupling temperatures of heavy quarks from the medium, ranging between 130 and $180\mathrm{MeV}$. We present calculations of the nuclear modification factor $R_{AA}$, as well as of the elliptic flow $v_2$ in Au + Au collisions at $\sqrt{s_{NN}}=200\text{GeV}$ and Pb + Pb collisions at $\sqrt{s_{NN}}=2.76\mathrm{TeV}$. To make our results comparable to experimental data at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC), we implement a Peterson fragmentation and a quark coalescence approach followed by semileptonic decay of the D and B mesons to electrons. We find that our results strongly depend on the decoupling temperature and the hadronization mechanism. At a decoupling temperature of $130\mathrm{MeV}$ we reach a good agreement with the measurements at both the RHIC and the LHC energies simultaneously for the elliptic flow $v_2$ and the nuclear modification factor $R_{AA}$.

We study the production of strange hadrons in nucleus-nucleus collisions from 4 to $160 A$ GeV within the parton-hadron-string dynamics (PHSD) transport approach that is extended to incorporate essentials aspects of chiral symmetry restoration (CSR) in the hadronic sector (via the Schwinger mechanism) on top of the deconfinement phase transition as implemented in PHSD. Especially the $K^{+}/{\pi }^{+}$ and the $(\mathrm{\Lambda }+{\mathrm{\Sigma }}^0)/{\pi }^{-}$ ratios in central Au+Au collisions are found to provide information on the relative importance of both transitions. The modeling of chiral symmetry restoration is driven by the pion-nucleon $\mathrm{\Sigma }$ term in the computation of the quark scalar condensate $\langle \overline{q}q\rangle$ that serves as an order parameter for CSR and also scales approximately with the effective quark masses $m_s$ and $m_q$. Furthermore, the nucleon scalar density ${\rho }_s$, which also enters the computation of $\langle \overline{q}q\rangle$, is evaluated within the nonlinear $\sigma -\omega$ model which is constrained by Dirac-Brueckner calculations and low-energy heavy-ion reactions. The Schwinger mechanism (for string decay) fixes the ratio of strange to light quark production in the hadronic medium. We find that above $\sim 80 A$ GeV the reaction dynamics of heavy nuclei is dominantly driven by partonic degrees of freedom such that traces of the chiral symmetry restoration are hard to identify. Our studies support the conjecture of “quarkyonic matter” in heavy-ion collisions from about 5 to $40 A$ GeV and provide a microscopic explanation for the maximum in the $K^{+}/{\pi }^{+}$ ratio at about $30 A$ GeV, which only shows up if a transition to partonic degrees of freedom is incorporated in the reaction dynamics and is discarded in the traditional hadron-string models.

Ternary fission of superheavy nuclei is studied within the three-cluster model potential energy surfaces (PESs). Due to shell effects, the stability of superheavy nuclei has been predicted to be associated with $Z=114$, 120, and 126 for protons and $N=184$ for neutrons. Taking some representative nuclei we have extended the ternary fission studies to superheavy nuclei. We adopted two minimization procedures to minimize the potential and considered different arrangements of the fragments. The PES from one-dimensional minimization reveals a strong cluster region favoring various ternary breakups for an arrangement in which the lightest fragment is kept at the center. The PES obtained from two-dimensional minimization reveals strong preference of ternary fragmentation in the true ternary fission region. Though the dominant decay mode of superheavy nuclei is $\alpha$ decay, the $\alpha$-accompanied ternary breakup is found to be a nonfavorable one. Further, the prominent ternary combinations are found to be associated with the neutron magic number.