The application of the Lorentz integral transform (LIT) method to photon scattering off nuclei is presented in general. As an example, elastic photon scattering off the deuteron in the unretarded dipole approximation is considered using the LIT method. The inversion of the integral transform is discussed in detail, paying particular attention to the high-energy contributions in the resonance term. The obtained $E1$ polarizabilities are compared to results from the literature. The corresponding theoretical cross section is confronted with experimental results confirming, as already known from previous studies, that the $E1$ contribution is the most important one at lower energies.

The tensor polarization ${\rho }_{20}$ of deuterons emitted in the ${}^1\mathrm{H}{(}^3\mathrm{He},\overleftrightarrow{d})X$ reaction at $0^{\circ }$ in the laboratory system was measured at the Saturne National Laboratory in Saclay using the SPES-4 spectrometer with the HYPOM polarimeter located downstream from its focal plane. The momentum of the detected deuterons was kept fixed at 3.77 GeV$/c$, while the momentum of the ${}^3\mathrm{He}$ beam was varied from 4.60 to 5.66 GeV$/c$, thus providing a range of internal momenta $k$ of the deuteron in ${}^3\mathrm{He}$ from 0 up to 0.4 GeV$/c$. The data obtained are compared with theoretical predictions.

Background: Proton-proton bremsstrahlung ($pp\gamma$) is investigated both theoretically and experimentally. The $pp\gamma$ amplitudes can be classified according to the number and location of on-shell points at which they are evaluated. Quantitative understanding of the effect on the $pp\gamma$ cross section of using different on-shell-point conditions is lacking, but it is essential to identifying the photon emission mechanism governing the $pp\gamma$ process. Method: Four different $pp\gamma$ amplitudes, which include four-on-shell-point amplitudes and one-on-shell-point amplitude, are generated from a realistic one-boson-exchange (ROBE) model for $pp$ scattering. These ROBE amplitudes are used to investigate the consequence of using different on-shell-point conditions in calculating the $pp\gamma$ cross sections. Purpose: We verify the validity of the ROBE $pp\gamma$ amplitudes. We explore similarities between the four-on-shell-point ROBE and two-$u$-two-$t$ special (TuTts) soft-photon $pp\gamma$ amplitudes and important differences with the one-on-shell-point ROBE and Low $pp\gamma$ amplitudes. We demonstrate that the precision Kernfysisch Versneller Instituut (KVI) data can only be described by the four-on-shell-point (ROBE or TuTts) amplitude. We use the ROBE four-on-shell-point amplitude and one-on-shell-point amplitude to investigate systematically the effect of using different on-shell-point conditions to calculate the $pp\gamma$ cross section. Furthermore, we identify a general principle that governs the process. This general principle is also applicable to other bremsstrahlung processes involving the scattering of two identical nucleons. Results: (i) The four-on-shell-point ROBE (or TuTts) amplitude describes the high-precision KVI data much better than does the one-on-shell-point ROBE (or Low) amplitude. Although the contribution from the anomalous magnetic moment of the proton is very significant, it does not completely dominate the KVI $pp\gamma$ cross sections. (ii) The four-on-shell-point ROBE (or TuTts) amplitude describes the TRIUMF data better than does the one-on-shell-point ROBE (or Low) amplitude. (iii) The effect on the $pp\gamma$ cross section of using different on-shell-point conditions is significant in the hard-photon region, i.e., for small proton scattering angles $\theta$ ($={\theta }_3={\theta }_4$, symmetric scattering angles) far from the elastic limit ($\theta \to {45}^{\circ }$); in contrast, the effect becomes insignificant in the vicinity of the elastic limit. Near the limit as $\theta$ tends to ${45}^{\circ }$ (or as the photon energy $K$ approaches zero), the four-on-shell-point and one-on-shell-point amplitudes approach one another, a general principle applicable to all bremsstrahlung processes because only kinematics is involved. Conclusion: The four-on-shell-point ROBE amplitude provides a quantitative description of $pp\gamma$ cross sections. The anomalous magnetic moment is an important component of the photon emission mechanism. The four-on-shell-point property of the full ROBE amplitude is essential to properly describing the complete range of the precision KVI data and the TRIUMF data, although the one-on-shell-point ROBE amplitude is adequate in the region near the elastic limit.

We study the correlation between the thickness of the neutron skin in finite nuclei and the nuclear symmetry energy for isotopic chains of even-even Ni, Sn, and Pb nuclei in the framework of the deformed self-consistent mean-field Skyrme HF + BCS method. The symmetry energy, the neutron pressure, and the asymmetric compressibility in finite nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy density functional. The mass dependence of the nuclear symmetry energy and the neutron-skin thickness are also studied together with the role of the neutron-proton asymmetry. A correlation between the parameters of the equation of state (symmetry energy and its density slope) and the neutron skin is suggested in the isotopic chains of Ni, Sn, and Pb nuclei.

The finite-range adiabatic wave approximation (ADWA) provides a practical method to analyze ($d,p$) or ($p,d$) reactions; however, until now the level of accuracy obtained in the description of the reaction dynamics has not been determined. In this work, we perform a systematic comparison between the finite-range adiabatic wave approximation and the exact Faddeev method. We include studies of ${}^{11}$Be($p,d$)${}^{10}$Be(g.s.) at $E_p=5$, 10, and 35 MeV; ${}^{12}$C($d,p$)${}^{13}$C(g.s.) at $E_d=7$, 12, and 56 MeV; and ${}^{48}$Ca($d,p$)${}^{49}$Ca(g.s.) at $E_d=19$, 56, and 100 MeV. Results show that the two methods agree within $\approx$5$\%$ for a range of beam energies ($E_d\approx 20$–40 MeV) but differences increase significantly for very low energies and for the highest energies. Our tests show that ADWA agrees best with the Faddeev method when the angular momentum transfer is small $\Delta l=0$ and when the neutron-nucleus system is loosely bound.

By calculating the Wigner distribution function in the reaction plane, we are able to probe the phase-space behavior in the time-dependent Hartree-Fock scheme during a heavy-ion collision in a consistent framework. Various expectation values of operators are calculated by evaluating the corresponding integrals over the Wigner function. In this approach, it is straightforward to define and analyze quantities even locally. We compare the Wigner distribution function with the smoothed Husimi distribution function. Different reaction scenarios are presented by analyzing central and noncentral ${}^{16}$O ${+}^{16}$O and ${}^{96}$Zr ${+}^{132}$ Sn collisions. Although we observe strong dissipation in the time evolution of global observables, there is no evidence for complete equilibration in the local analysis of the Wigner function. Because the initial phase-space volumes of the fragments barely merge and mean values of the observables are conserved in fusion reactions over thousands of fm$/c$, we conclude that the time-dependent Hartree-Fock method provides a good description of the early stage of a heavy-ion collision but does not provide a mechanism to change the phase-space structure in a dramatic way necessary to obtain complete equilibration.

Based on the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model plus the Skyrme force parameters, the initialization effect is studied in heavy-ion collisions at intermediate energies. We find that there are moderate initialization effects in the following observables: free neutron to proton ratio ($n/p$), ${\pi }^{-}/{\pi }^{+}$ ratio, and neutron to proton differential flow ($F_{n-p}^x$). Effects of initialization are larger for charged ${\pi }^{-}/{\pi }^{+}$ ratios than for $n/p$ ratios. And the effects of initialization are more evident in nuclear reactions at lower incident beam energies. We do not see large effects of initialization for light reaction systems or large asymmetric (neutron-richer) reaction systems. We also see relatively large effects of initialization on the neutron to proton differential flow at relatively lower incident beam energies or with large impact parameters. These results may be useful for the delicate studies of the equation of state of asymmetric nuclear matter.

Using the two-component model that includes charmonium production from both initial nucleon-nucleon hard scattering and regeneration in the produced quark-gluon plasma, we study $J/\psi$ production in heavy-ion collisions at the Super Proton Synchrotron (SPS), Relativistic Heavy Ion Collider (RHIC), and Large Hadron Collider (LHC). For the expansion dynamics of produced hot dense matter, we use a schematic viscous hydrodynamic model with the specific shear viscosity in the quark-gluon plasma and the hadronic matter taken, respectively, to be two and ten times the lower bound of $1/4\pi$ suggested by the anti-de Sitter/conformal field theory (AdS/CFT) correspondence. For the initial dissociation and the subsequent thermal decay of charmonia in the hot dense matter, we use the screened Cornell potential to describe the properties of charmonia and perturbative QCD to calculate their dissociation cross sections. Including regeneration of charmonia in the quark-gluon plasma via a kinetic equation with in-medium chamonium decay widths, we obtain a good description of measured $J/\psi$ nuclear modification factors in Pb $+$ Pb collisions at $\sqrt{s_{NN}}=1.73$ GeV at SPS and in Au $+$ Au collisions at $\sqrt{s_{NN}}=200$ GeV at RHIC. A reasonable description of the measured nuclear modification factor of high transverse momenta $J/\psi$ in Pb $+$ Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV at LHC is also obtained.

The thermal evolution of neutron stars depends on the elementary excitations affecting the stellar matter. In particular, the low-energy excitations, whose energy is proportional to the transferred momentum, can play a major role in the emission and propagation of neutrinos. In this paper, we focus on the density modes associated with the proton component in the homogeneous matter of the outer core of neutron stars (at density between one and three times the nuclear saturation density, where the baryonic constituents are expected to be neutrons and protons). In this region, it is predicted that the protons are superconducting. We study the respective roles of the proton pairing and Coulomb interaction in determining the properties of the modes associated with the proton component. This study is performed in the framework of the random phase approximation, generalized in order to describe the response of a superfluid system. The formalism we use ensures that the generalized Ward’s identities are satisfied. An important conclusion of this work is the presence of a pseudo-Goldstone mode associated with the superconducting protons in neutron-star matter. Indeed, the Goldstone mode, which characterizes a pure superfluid, is suppressed in usual superconductors because of the long-range Coulomb interaction, which allows a plasmon mode. However, for the proton component of stellar matter, the Coulomb field is screened by the electrons and a pseudo-Goldstone mode occurs, with a velocity increased by the Coulomb interaction.

Neutron star crustal matter, whose properties are relevant in many models aimed at explaining observed astrophysical phenomena, has so far always been studied using a mean-field approach. To check the results obtained in this way, a sensible next step is to make use of a realistic nuclear potential. The present paper extends the periodic box Fermi hypernetted chain method to include longitudinal-isospin dependence of the correlations, making feasible a study of asymmetric crustal matter. Results are presented for the symmetry energy, the low-density neutron star equation of state, and the single-particle neutron and proton energies.

Excited states in ${}^{165}$Er have been populated using the ${}^{160}$Gd(${}^9$Be, 4$n$) reaction at beam energies of 42 and 45 MeV. A band consisting of two levels at excitation energies of 1317.6 and 1505.9 keV, both of which decay strongly to the $11/2^{-}\left[505\right]$ band, is observed and assigned as the $\gamma$-vibrational band built on the $11/2^{-}\left[505\right]$ configuration. In addition, a newly identified level is proposed as a three-quasiparticle state.

Gamma rays assigned to ${}_{28}^{72}$Ni${}_{44}^{}$ have been identified with Gammasphere in deep-inelastic reactions involving a 450-MeV ${}^{76}$Ge beam and a ${}^{198}$Pt target. Using a combination of spectra produced by double gates on the known 454-, 843-, and 1095-keV members of the ground-state cascade, a coincident line at 199 keV has been identified and is tentatively assigned as the $8^{+}\to 6^{+}$ transition. These $\gamma$-ray coincidences have been observed only in prompt events, indicating an $8^{+}$ half-life below 20 ns and requiring a large $B\left(E2\right)$ enhancement compared to that expected from a seniority scheme. This value is consistent with models showing decay to a seniority $\nu =4,$ $6^{+}$ level that is depressed by the same two-body interaction responsible for the rather low 1095-keV $2_1^{+}$ energy, as compared to the valence-symmetry counterpart ${}_{44}^{94}$Ru${}_{50}^{}$.

We studied the role of the tensor interaction in He isotopes systematically on the basis of the tensor-optimized shell model (TOSM). We use a bare nucleon-nucleon interaction AV8${}^{\prime }$ obtained from nucleon-nucleon scattering data. The short-range correlation is treated in the unitary correlation operator method (UCOM). Using the TOSM + UCOM approach, we investigate the role of tensor interaction on each spectrum in He isotopes. It is found that the tensor interaction enhances the $LS$ splitting energy observed in ${}^5$He, in which the $p_{1/2}$ and $p_{3/2}$ orbits play different roles on the tensor correlation. In ${}^{6,7,8}$He, the low-lying states containing extra neutrons in the $p_{3/2}$ orbit gain the tensor contribution. On the other hand, the excited states containing extra neutrons in the $p_{1/2}$ orbit lose the tensor contribution due to the Pauli-blocking effect with the $2p2h$ states in the ${}^4$He core configuration.

For the $A=32$, $T=2$ quintet we provide a unified theoretical description for three related aspects of isospin mixing: the necessity of more than three terms in the isobaric mass multiplet equation, isospin-forbidden proton decay in ${}^{32}$Cl, and a correction to the allowed Fermi ${\beta }^{+}$ decay of ${}^{32}$Ar. We demonstrate that all three effects observed in experiment can be traced to a common origin related to isospin mixing of the $T=2$ states with $T=1$ states.

We show that particle species dependence of enhanced hadron production at intermediate transverse momentum ($p_T$) for $d+\text{Au}$ collisions at RHIC can be understood in terms of the hadronization from string fragmentation and the subsequent hadronic rescatterings in the final state. A multiphase transport model (AMPT) with two different hadronization mechanisms, string fragmentation or parton coalescence, is used in our study. When the hadrons are formed from string fragmentation, the subsequent hadronic rescatterings will result in particle mass dependence of the nuclear modification factor $R_{\mathrm{CP}}$, which is consistent with the present experimental data. On the other hand, in the framework of parton coalescence, the mass dependence disappears and the strangeness plays an important role in hadron production.

The breakup reactions of ${}^{31}\text{Cl}+{}^{12}\text{C}$ at 44$A$ MeV are investigated experimentally. The longitudinal momentum distribution of ${}^{30}$S after one-proton removal from ${}^{31}$Cl has been obtained. By assuming core plus a valence proton structure, the momentum distribution is studied using the few-body Glauber model. The calculation shows that the width of momentum distribution for a valence proton with $l=2$ is consistent with the experimental data, which indicates a dominant $d$-wave component for the valence proton in ${}^{31}$Cl.

Microscopic analysis of the recently reported 295-MeV-proton scattering data from Pb isotopes and ${}^{58}$Ni is presented within the framework of the Brueckner-Hartree-Fock theory. The effective interaction (g matrix) has been calculated using three Hamiltonians with Urbana v-14, Argonne v-18, and Ried93 internucleon potentials. The microscopic optical potential is calculated by folding the effective interactions over nucleon density distributions obtained in the relativistic mean field framework. The Argonne v-18 and Ried93 interactions have been used for the first time to calculate the nucleon-nucleus optical potential. The calculations reproduce the experiment well thus revalidating the use of microscopic optical potential in such analyses.

We report on a theoretical study of the $pp\to p\Lambda K^{+}$ and $pp\to p{\Sigma }^0{K}^{+}$ reactions near threshold using a chiral dynamical approach. The production process is described by single-pion and single-kaon exchange. The final state interactions of nucleon-hyperon, $K$-hyperon, and $K$-nucleon systems are also taken into account. We show that our model leads to a fair description of the experimental data on the total cross section of the $pp\to p\Lambda K^{+}$ and $pp\to p{\Sigma }^0{K}^{+}$ reactions. We find that the experimental observed strong suppression of ${\Sigma }^0$ production compared to $\Lambda$ production at the same excess energy can be explained. However, ignorance of phases between some amplitudes does not allow one to properly account for the nucleon-hyperon final state interaction for the $pp\to p{\Sigma }^0{K}^{+}$ reaction. We also demonstrate that the invariant mass distribution and the Dalitz plot provide direct information about the $\Lambda$ and ${\Sigma }^0$ production mechanisms and may be tested by experiments at COSY or HIRFL-CSR.

Microscopic optical model potentials, based on density-dependent effective interactions, involve multidimensional integrals to account for the full Fermi motion of the target struck nucleon throughout the nucleus. If a spherical matter distribution is assumed, then each matrix element of the optical potential requires the evaluation of seven-dimensional integrals. In this work we provide a full account of these integrals, retaining the genuine off-shell structure of the nucleon-nucleon effective interaction. The evaluation is based on the asymptotic separation of the optical model potential for nucleon-nucleus scattering in momentum space, where the potential is split into a free $t$-matrix contribution and another which depends exclusively on the gradient of the density-dependent $g$ matrix. The calculated potentials, based on the Paris nucleon-nucleon ($NN$) potential, are applied to proton elastic scattering from ${}^{16}$O and ${}^{90}$Zr at beam energies between 30 and 65 MeV. The results were compared with two approximations to the unabridged expression, revealing moderate differences among their scattering observables. When comparing with results based on the Argonne $v_{18}$ $NN$ potential, these differences appear smaller than those attainable by the choice of the internucleon potential.

Assuming that the ratio between asymptotic normalization coefficients of mirror states is model independent, charge symmetry can be used to indirectly extract astrophysically relevant proton capture reactions on proton-rich nuclei based on information on stable isotopes. The assumption has been tested for light nuclei within the microscopic cluster model. In this work we explore the Hamiltonian independence of the ratio between asymptotic normalization coefficients of mirror states when deformation and core excitation is introduced in the system. For this purpose we consider a phenomenological $\mathrm{rotor}+N$ model where the valence nucleon is subject to a deformed mean field and the core is allowed to excite. We apply the model to ${}^8$Li/${}^8$B, ${}^{13}$C/${}^{13}$N, ${}^{17}$O/${}^{17}$F, ${}^{23}$Ne/${}^{23}$Al, and ${}^{27}$Mg/${}^{27}$P. Our results show that, for most studied cases, the ratio between asymptotic normalization coefficients of mirror states is independent of the strength and multipolarity of the couplings induced. The exception is for cases in which there is an $s$-wave coupled to the ground state of the core, the proton system is loosely bound, and the states have large admixture with other configurations. We discuss the implications of our results for novae.