$d^{*}$ dibaryon study is a critical test of hadron interaction models. The electroproduction cross sections of $e\overrightarrow{d}{\mathrm{ed}}^{*}$ have been calculated based on the meson exchange current model. The cross section around 30 degrees of 1 GeV electron in the laboratory frame is about 10 nb, which is about two orders smaller than that of the quasielastic and Δ resonance production. A special kinematics and detector system must be studied to pin down the weak signal of $d^{*}$ resonance from the strong background.

We investigate the effect on the nuclear matter equation of state (EOS) due to modification of meson and nucleon parameters in a nuclear medium as a consequence of the partial restoration of chiral symmetry. To get the EOS, we have used Brueckner-Bethe-Goldstone formalism with Bonn-B potential as a two-body interaction and QCD sum rule and Brown-Rho scaling prescriptions for modification of hadron parameters. We find that the EOS is very much sensitive to the meson parameters. We can fit, with the two-body interaction alone, both the saturation density and the binding energy per nucleon.

A measurement of parity-violating spin-dependent $\gamma \overrightarrow{p}$ Compton scattering will provide a theoretically clean determination of the parity-violating pion-nucleon coupling constant $h_{\pi \mathrm{NN}}^{\mathrm{}\left(1\right)\mathrm{}}.$ We calculate the leading parity-violating amplitude arising from one-loop pion graphs in chiral perturbation theory. An asymmetry of $\sim 5\times {10}^{-8}$ is estimated for Compton scattering of $100\hspace{0.5em}\mathrm{MeV}$ photons.

The odd-mass ${}^{117}\mathrm{Sn}$ nucleus was investigated in nuclear resonance fluorescence experiments up to an end point energy of the incident photon spectrum of 4.1 MeV at the bremsstrahlung facility of the Stuttgart University. More than 50 mainly hitherto unknown levels were found. From the measurement of the scattering cross sections model independent absolute excitation strengths were extracted. The measured angular distributions suggested the spins of 11 excited levels. Quasiparticle phonon model calculations including a complete configuration space were performed for the first time for a heavy odd-mass spherical nucleus. These calculations give a clear insight in the fragmentation and distribution of the $E1,$ $M1,$ and $E2\mathrm{}$ excitation strength in the low energy region. It is proven that the $1^{-}$ component of the two-phonon $[2_1^{+}\otimes 3_1^{-}]$ quintuplet built on top of the ${1/2}^{+}$ ground state is strongly fragmented. The theoretical calculations are consistent with the experimental data.

The proton emission from ground-state spherical nuclei is investigated exactly through the numerical solution of the time-dependent Schrödinger equation for initial single-proton quasistationary states. Contrary to common belief, it is shown that such calculations can be performed for any proton half-life ranging from ${10}^{-22}–20\mathrm{s},$ the longest proton lifetime observed at present. The important and careful choice of the initial metastable state is clarified. Applied to the calculation of the decay width of several ground-state spherical emitters, this method gives comparable results with the distorted wave-Born approximation and therefore justifies its use.

Pion excitation functions in proton-nucleus collisions, from the absolute threshold to 500 MeV, have been measured with 1 MeV beam energy resolution at the CELSIUS storage ring, operating in slow ramping mode. Total yields, angular distributions, and target mass dependence of ${\pi }^{+}$ production are generally reproduced well by QMD calculations. The ${\pi }^{+}/{\pi }^{-}$ ratios are not reproduced equally well, obviously because the detailed description of the pion interaction with the Coulomb field is very delicate.

We calculate, in a systematic way, the enhancement effect on $\overline{p}p$ and $\overline{p}A$ annihilation cross sections at low energy due to the initial state electrostatic interaction between the projectile and the target nucleus. This calculation is aimed at future comparisons between $\mathrm{n̄}$ and $\overline{p}$ annihilation rates on different targets for the extraction of pure isospin channels.

The photon production rate from a chemically equilibrating quark-gluon plasma likely to be produced at RHIC (BNL) and LHC (CERN) energies is estimated taking into account bremsstrahlung. The plasma is assumed to be in local thermal equilibrium, but with a phase space distribution that deviates from the Fermi or Bose distribution by space-time dependent factors (fugacities). The photon spectrum is obtained by integrating the photon rate over the space-time history of the plasma, adopting a boost invariant cylindrically symmetric transverse expansion of the system with different nuclear profile functions. Initial conditions obtained from a self-screened parton cascade calculation and, for comparison, from the HIJING model are used. Compared to an equilibrated plasma at the same initial energy density, taken from the self-screened parton cascade, a moderate suppression of the photon yield by a factor of 1 to 5 depending on the collision energy and the photon momentum is observed. The individual contributions to the photon production, however, are completely different in the both scenarios.

We present a superior proof of the fact that the summed strength isovector dipole, spin dipole, and orbital dipole excitations are independent of deformations at the $\Delta N=0\mathrm{}$ level and we give simple formulas for these summed strengths. The effects of different oscillator frequencies in the x, y, and z directions are also considered.

States in ${}^{92}\mathrm{Mo}$ have been observed with the ${(n,n}^{\prime }\gamma )$ reaction with spallation neutrons produced at the LANSCE-WNR facility. Gamma rays were detected with the GEANIE spectrometer, and the neutron energies were determined by the time-of-flight method. Combining excitation function and $\gamma \gamma$ coincidence analysis, 13 new levels have been deduced. The level scheme has been extended considerably for low- to medium-spin levels below 5 MeV in excitation energy.

Pseudospin symmetry relates the l-forbidden magnetic dipole transition strengths between pseudospin partners to the magnetic moments of the involved states. These relations are tested against experimental data after correction for the fragmentation of the single particle strengths. Within typical uncertainties of the experimental spectroscopic factors good agreement is found for a wide range of shell closures $Z=20\mathrm{}–82,\hspace{0.5em}N=20\mathrm{}-126,$ and pseudo-orbital angular momenta. Systematic deviations are observed for particle states above $N=28\mathrm{}$ and $Z=50\mathrm{}$ where the predicted $B\left(M1\mathrm{}\right)\mathrm{}$ values are about an order of magnitude too large.

Neutron total and elastic scattering cross sections have been measured over the neutron energy range 0.040–1.55 MeV. Spins and parities have been deduced for 90% of the resonances observed in the ${n+}^{52}\mathrm{Cr}$ reaction up to 1.05 MeV. This work brings into doubt a previously claimed parity dependence of the level spacing in ${}^{53}\mathrm{Cr}.$ We have used an R-matrix analysis to obtain resonance parameters for 194 resonances up to 1.05 MeV and strengths and level spacings for partial waves up to and including $d_{5/2}.$ The conventional s-, p-, and d-wave strength functions have been determined to be $3.5\pm 1.0,$ $0.44\pm 0.08,$ and $2.9\pm 0.4,$ respectively (in units of ${10}^{-4}).\mathrm{}$ This is the first work to report d-wave strength in this nuclide, identifying 87 additional resonances in this group. This, in turn, has resulted in a significant increase in the p-wave level spacing compared to that of two other similar works. Evidence is presented to explain differences among evaluated nuclear data files for this nuclide in terms of the influence of the strength outside the region upon the background cross section.

Based on schematic two-level models extended to $a_1$-meson degrees of freedom, we investigate possible mechanisms of chiral restoration in the vector–axial-vector channels in cold nuclear matter. In the first part of this article we employ the massive Yang-Mills framework to construct an effective chiral Lagrangian based on low-energy mesonic modes at finite density. The latter are identified through nuclear collective excitations of “meson”-sobar type such as $\pi \leftrightarrow \left[\Delta {\mathrm{}\left(1232\right)N}^{-1}\right]\equiv \hat{\pi },\hspace{0.5em}\hspace{0.5em}\rho \leftrightarrow \left[N^{*}{\mathrm{}\left(1520\right)N}^{-1}\right]\equiv \hat{\rho },$ etc. In a mean-field type treatment the in-medium gauge coupling $ĝ,$ the (axial-)vector meson masses and $f_{\pi }$ are found to decrease with density indicating the approach towards chiral restoration in the language of in-medium effective fields. In the second part of our analysis we evaluate the (first) in-medium Weinberg sum rule which relates vector and axial-vector correlators to the pion decay constant. Using in-medium $\rho {/a}_1$ spectral functions (computed in the two-level model) also leads to a substantial reduction of the pion decay constant with increasing density.

We point out that charge symmetry violation in both the valence and sea quark distributions of the nucleon has a nonperturbative source. We calculate this nonperturbative charge symmetry violation using the meson cloud model which has earlier been successfully applied to the study of SU(2) flavor asymmetry in the nucleon sea and quark-antiquark asymmetry in the nucleon. By taking into account the mass differences among hadron multiplets and assuming the coupling constants respect isospin, we find that the charge symmetry violation in the minority quark distribution is well below $1\%,$ which is consistent with most low energy tests but significantly smaller than most quark model predictions of about 2–10 %. Our prediction for the charge symmetry violation in the sea quark distribution is also much smaller than the quark model calculation.

Microscopic calculations of cross sections with density dependent interactions employing (a) RIKEN density distributions of helium isotopes for the derivation of the real part and (b) Bachelier et al. and Bray et al. imaginary part of the optical potential have been performed for the elastic scattering of ${}^6{\mathrm{H}\mathrm{e}+}^4\mathrm{He}$ and for ${}^6{\mathrm{H}\mathrm{e}+}^1\mathrm{H}.$ The results are in very good agreement with the recent experimental data of Oganessian et al.

High-spin states in the near proton-dripline nucleus ${}^{107}\mathrm{Sb}$ have been identified, and collectivity in this nucleus has been observed for the first time in the form of two rotational bands. One of the observed rotational structures is a $\Delta I=1\mathrm{}$ band, and is interpreted as based on a $\pi {(g}_{9/2}{)}^{-1}\otimes \pi {(g}_{7/2}{d}_{5/2}{)}^2$ proton configuration. A second structure has $\Delta I=2\mathrm{}$ character, and is explained as being based on a $\pi h_{11/2}\otimes [\pi {(g}_{9/2}{)}^{-2}\otimes \pi {(g}_{7/2}{d}_{5/2}{)}^2]$ proton configuration through comparison with cranked Nilsson-Strutinsky model calculations. The calculations predict that this band terminates at a spin of 79/2 $ħ.$

A new isomeric state has been identified at 302.2 keV excitation in ${}^{86}\mathrm{Y}$ populated by the ${}^{86}\mathrm{Sr}\mathrm{}(p,n),$ ${}^{86}\mathrm{Sr}\mathrm{}(d,2n),$ and ${}^{85}\mathrm{Rb}{(}^3\mathrm{He},2n)$ reactions at the energies $E_p=14\mathrm{}$ MeV, $E_d=13.5\mathrm{}$ MeV, and $E_{{}^3\mathrm{He}}=30\mathrm{}$ MeV. The decay scheme was investigated by pulsed-beam $\gamma$-ray spectroscopy. Its g factor was measured by the time-differential perturbed angular distribution method in external magnetic field. The isomer properties $T_{1/2}=125\mathrm{}$ ns, $J^{\pi }{=7\mathrm{}}^{-},$ and $g=-0.083\left(3\right)\mathrm{}$ were determined. The transition strength and the g factor indicate a superposition of single-particle and collective contributions. The g factor $g=+0.542\mathrm{}\left(9\right)\mathrm{}$ has been determined for the ${5/2}^{-}\hspace{0.5em}266.3$ keV 178 ns isomeric state in ${}^{85}\mathrm{Y}.$

The in-medium neutron-proton, proton-proton (neutron-neutron) scattering cross sections $({\sigma }_{\mathrm{np}}^{*},$ ${\sigma }_{\mathrm{pp}\left(\mathrm{nn}\right)\mathrm{}}^{*})$ are studied based on QHD-II type Lagrangian within the framework of the microscopic transport theory. The results demonstrate that, for free nucleon-nucleon scattering cross sections, the isospin dependence is dominantly caused by the $\rho$ meson field. The medium correction of nucleon-nucleon scattering cross sections is also isospin dependent, ${\sigma }_{\mathrm{np}}^{*}$ depends on the baryon density weakly and ${\sigma }_{\mathrm{pp}\left(\mathrm{nn}\right)\mathrm{}}^{*}$ depends on the baryon density significantly, which is due to the different effects of the medium correction of nucleon mass and $\rho$ meson mass on ${\sigma }_{\mathrm{np}}$ and ${\sigma }_{\mathrm{pp}\left(\mathrm{nn}\right)\mathrm{}},$ respectively.

Differential cross sections for the elastic scattering of ${}^4\mathrm{He}$ from ${}^4\mathrm{He}$ have been measured at 280 and 620 MeV. The data exhibit systematic energy dependence when compared with measurements at lower energies. Optical model analysis indicates that the Woods-Saxon potential fails to reproduce the large angle data. Satisfactory fits are obtained by adding a Woods-Saxon squared form factor to the real central potential.

The variational Monte Carlo method is used to find the ground state of six quarks confined to a cavity of diameter $R_c,$ interacting via an assumed nonrelativistic constituent quark model Hamiltonian. We use a flux-tube model augmented with one-gluon and one-pion exchange interactions, which has been successful in describing single hadron spectra. The variational wave function is written as a product of three-quark nucleon states with correlations between quarks in different nucleons. We study the role of quark exchange effects by allowing flux-tube configuration mixing. An accurate six-body variational wave function is obtained. It has only ∼13% rms fluctuation in the total energy and yields a standard deviation of ≲0.1%; small enough to be useful in discerning nuclear interaction effects from the large rest mass of the two nucleons. Results are presented for three values of the cavity diameter, $R_c=2,$ 4, and 6 fm. They indicate that the flux-tube model Hamiltonian with gluon and pion exchange requires revisions in order to obtain agreement with the energies estimated from realistic two-nucleon interactions. We calculate the two-quark probability distribution functions and show how they may be used to study and adjust the model Hamiltonian.