Various modern nucleon-nucleon $\mathrm{}\left(\mathrm{NN}\right)\mathrm{}$ potentials yield a very accurate fit to the nucleon-nucleon scattering phase shifts. The differences between these interactions in describing properties of nuclear matter are investigated. Various contributions to the total energy are evaluated employing the Hellmann-Feynman theorem. Special attention is paid to the two-nucleon correlation functions derived from these interactions. Differences in the predictions of the various interactions can be traced back to the inclusion of nonlocal terms.

A measurement of the ${}^{12}\mathrm{C}(\gamma ,{\pi }^{+}{n)}^{11}\mathrm{B}$ reaction in quasifree $\pi$-production kinematic regimes has been performed using tagged photons in conjunction with large solid angle $\pi$ and n detectors. The aim of the experiment was to investigate predicted modifications to the $\Delta$ excitation of nucleons and their subsequent propagation and decay, brought about by the nuclear medium. Differential cross sections are presented for photon energies spanning the $\Delta \mathrm{}\left(1232\right)\mathrm{}$ excitation region. The measurements are consistent with distorted wave impulse approximation calculations in which the amplitude for proton $\Delta$ excitation, followed by $\Delta$ propagation and decay to ${\pi }^{+}+n,$ is reduced compared to that for a free p. However, because of uncertainties in the magnitudes of the final state interactions, it is concluded that improved calculations are required to obtain a quantitative estimate of $\Delta$-medium effects.

The scaled factorial moments $F_q$ are studied for a second-order quark-hadron phase transition within the Ginzburg-Landau description. The role played by the ground state of the system under low temperature is emphasized. After a local shift of the order parameter the fluctuations are around the ground state, and a perturbative calculation for $F_q$ can be carried out. Power scaling between $F_q$’s is shown, and a universal scaling exponent $\nu \simeq 1.75$ is given for the case with weak correlations and weak self-interactions.

We study here the onset of thermal equilibrium affecting the lifetimes of ${}^{26}\mathrm{Al}$ and ${}^{34}\mathrm{Cl}$ nuclei within a hot astrophysical photon gas. The ${}^{26}\mathrm{Al}$ isotope is of prime interest for γ-ray astronomy with the observation of its delayed ${(t}_{1/2}=0.74\mathrm{}$ My) 1.809 MeV $\gamma$-ray line. Its nucleosynthesis is complicated by the presence of a short lived ${(t}_{1/2}=6.34\mathrm{}$ s) spin isomer. A similar configuration is found in ${}^{34}\mathrm{Cl}$ where the decay of its isomer ${(}^{34m}\mathrm{Cl},$ $t_{1/2}=32\mathrm{}$ m) is followed by delayed $\gamma$-ray emission with characteristic energies. The lifetimes of such nuclei are reduced at high temperature by the thermal population of shorter lived levels. However, thermal equilibrium within ${}^{26}\mathrm{Al}$ and ${}^{34}\mathrm{Cl}$ levels is delayed by the presence of the isomer. We study here the transition to thermal equilibrium where branching ratios for radiative transitions are needed in order to calculate lifetimes. Since some of these very small branching ratios are not known experimentally, we use results of shell model calculations.

High-spin levels in the heaviest stable isotope of chromium were observed following the fusion-evaporation reaction ${}^{12}\mathrm{C}{(}^{48}\mathrm{Ca},\alpha {2n)}^{54}\mathrm{Cr}$ at a beam energy of 157 MeV, using the GAMMASPHERE and MICROBALL detector arrays. Numerous yrast and near yrast levels are reported, and previously assigned $7^{+}$ and $9^{+}$ levels are suggested to be $5^{+}$ and $7^{+},$ respectively. The inferred level scheme is compared with shell model calculations.

The high-spin states of ${}^{143}\mathrm{Nd}$ have been studied in the ${}^{130}\mathrm{Te}{(}^{18}\mathrm{O}{,5n)}^{143}\mathrm{Nd}$ reaction at a beam energy of 80 MeV using techniques of in-beam $\gamma$-ray spectroscopy. Measurements of $\gamma -\gamma -t$ coincidences, $\gamma$-ray angular distributions, and $\gamma$-ray linear polarizations were performed. A level scheme of ${}^{143}\mathrm{Nd}$ with spin and parity assignments up to ${53/2}^{+}$ is proposed, including a high-lying isomer with a measured half-life of $35\pm 8\hspace{0.5em}\mathrm{ns}.$ While a weak coupling model can explain the level structure up to the $J^{\pi }{=39/2\mathrm{}}^{-}$ state, this model cannot reproduce the higher-lying states. The characteristics of the high-spin isomer, as well as the level structure in ${}^{143}\mathrm{Nd},$ were also stressed with a deformed independent particle model.

The previous treatments for strange quark matter in the quark mass-density-dependent model have unreasonable vacuum limits. We provide a method to obtain the quark mass parametrizations and give a self-consistent thermodynamic treatment which includes the MIT bag model as an extreme. In this treatment, strange quark matter in bulk still has the possibility of absolute stability. However, the behavior of the sound velocity is opposite to previous findings.

In this Comment, we propose possible errors in constructing the continuum contribution in the sum rule studied by M. C. Birse and B. Krippa [Phys. Rev. C 54, 3240 (1996)].

In response to Kim’s Comment [Phys. Rev. C 61, 019801 (1999)] on our sum rules for poin-baryon coupling constants, we point out that our treatment of the continuum is consistent with duality and with the fact that the correlator in the presence of an external meson or field should be represented by a double dispersion relation.

Inclusive $K^{+}$ and exclusive $K^{+}Y$ photoproduction on the deuteron are investigated theoretically. Modern hyperon-nucleon forces and a recently updated kaon photoproduction operator for the $\gamma +\overrightarrow{N}{K}^{+}+Y$ process are used. Sizable effects of the hyperon-nucleon final state interaction are found near the $K^{+}\Lambda N$ and $K^{+}\Sigma N$ thresholds in the inclusive reaction. Angular distributions for the exclusive process show clear $\mathrm{YN}$ final state interaction effects in certain kinematic regions. Precise data especially for the inclusive process around the $K^{+}\Sigma N$ threshold would help to clarify the strength and property of the $\Lambda N-\Sigma N$ interaction.

Methods of large amplitude collective motion in the adiabatic limit are examined with a special emphasis on conservation laws. We show that the restriction to point transformations, which is a usual assumption of the adiabatic time-dependent mean-field theory, needs to be lifted. In order to facilitate the application of large-amplitude collective motion techniques, we examine the possibility of representing the random-phase-approximation normal-mode coordinates by linear combinations of a limited number of one-body operators. We study the pairing-plus-quadrupole model of Baranger and Kumar as an example, and find that such representations exist in terms of operators that are state dependent in a characteristic manner.

We follow up on our earlier work involving a light projectile ${(}^{48}\mathrm{Ca})$ to populate high spin states in neutron-rich nuclei with results from experiments involving a heavier projectile ${(}^{154}\mathrm{Sm})$ for the purposes of studying isotopic yields. These yields, which in some cases were measurable down to a level of 0.1% of the total reaction cross section, are presented from three separate reactions. A trend in the isotopic yields towards $N/Z$ equilibration is observed in one experiment having a large disparity in $N/Z$ ratios between the projectile and target. In the two other reactions, where the $N/Z$ driving force is less pronounced, the yields are instead clustered around the projectile and target nuclei. We present correlated projectilelike and targetlike fragment isotopic yields derived from $\gamma -\gamma$ coincidences, a technique that enables one to partition the yield of an isotope according to the amount of neutron evaporation. Using this method we find that for the zero-neutron evaporation channel transfer occurs predominantly into the light fragment, consistent with the nature of the deep-inelastic mechanism. We further find that multiple-neutron evaporation contributes substantially to the yields of the isotopes.

Excitation energy dependence of the cross sections of the reactions ${}^{208}{\mathrm{Pb}}_{126}{(}^{50}{\mathrm{Ti}}_{28}{,1n)}^{257}{\mathrm{Rf}}_{153}$ and ${}^{208}{\mathrm{Pb}}_{126}{(}^{58}{\mathrm{Fe}}_{32}{,1n)}^{265}{\mathrm{Hs}}_{157}$ is calculated and compared with the experimental data measured at GSI-Darmstadt. Such a dependence is also calculated for the reaction ${}^{208}{\mathrm{Pb}}_{126}{(}^{86}{\mathrm{Kr}}_{50}{,1n)}^{293}{118}_{175}$ reported recently by the Berkeley group, and for reactions which may lead to the synthesis of element 119 and production of its odd-$Z$ descendants. Recommendations for future experiments based on the present study are presented.

New SAPHIR $p\left(\gamma {,K}^{+}\right)\Lambda$ total cross section data show a resonance structure at a total c.m. energy around 1900 MeV. We investigate this feature with an isobar model and find that the structure can be well explained by including a new $D_{13}$ resonance at 1895 MeV. Such a state has been predicted by a relativistic quark model at 1960 MeV with significant $\gamma N$ and $K\Lambda$ branching ratios. We demonstrate how the measurement of the photon asymmetry can be used to further study this resonance. In addition, verification of the predicted large decay widths into the $\eta N$ and ${\eta }^{\prime }N$ channels would allow distinguishing between other nearby $D_{13}$ states.

The influence of a reduced $\sigma$-meson mass on previously calculated in-medium $\pi \pi$ correlations in the $J=I=0\mathrm{}$ (σ-meson) channel is investigated. It is found that the invariant-mass distribution around the vacuum threshold experiences a further strong enhancement with respect to standard many-body effects. The relevance of this result for the explanation of recent $A(\pi ,2\mathrm{}\pi )X$ data is pointed out.

We calculate the initial nonequilibrium conditions from perturbative QCD within Glauber multiple-scattering theory for $\sqrt{s}=200A\hspace{0.5em}\mathrm{GeV}$ and $\sqrt{s}=5.5A\hspace{0.5em}\mathrm{TeV}.$ At the soon available collider energies one will particularly test the small-$x$ region of the parton distributions entering the cross sections. Therefore, shadowing effects, previously more or less unimportant, will lead to new effects on variables such as particle multiplicities $dN/dy,$ transverse energy production $d{E}_T/dy,$ and the initial temperature $T_i.$ In this paper we will take a closer look at the effects of shadowing by employing different parametrizations for the shadowing effect for valence quarks, sea quarks, and gluons. Since the cross sections at midrapidity are dominated by processes involving gluons the amount of their depletion is particularly important. We will therefore take a closer look at the results for $dN/dy,$ $d{E}_T/dy,$ and $T_i$ by using two different gluon shadowing ratios, differing strongly in size. As a matter of fact, the calculated quantities differ significantly.

The effects of neutron excess on the formation of $\Delta \mathrm{}(3,3)\mathrm{}$ resonance states in exotic nuclei at equilibrium and under large amplitude compression have been investigated within the radial constraint spherical Hartree-Fock method. An effective Hamiltonian has been used which includes the $\Delta$ degree of freedom explicitly. Results are presented for ${}^{28}\mathrm{O},$ ${}^{60}\mathrm{Ca},$ and ${}^{70}\mathrm{Ca}$ in a model space of seven major oscillator shells and eight $\Delta$ orbitals. The results show that the formation of the Δ’s depends strongly on the amount of neutron excess in the nuclear system. In contrast to previous work where we found no Δ’s in ${}^{16}\mathrm{O}$ and ${}^{40}\mathrm{Ca}$ at equilibrium, these results show that a significant amount of Δ’s exists at equilibrium in exotic isotopes. In addition, as the nucleus is compressed to a density of 2.5 times the ordinary nuclear density, the percentage of the Δ’s rises to 3%, 5%, and 7% of the total number of all baryons in ${}^{28}\mathrm{O},$ ${}^{60}\mathrm{Ca},$ and ${}^{70}\mathrm{Ca},$ respectively. This suggests a parametrization for the percentage of the Δ’s created at 2.5 times the normal density of the form $0.25\left(N-Z\right)\%.\mathrm{}$ The results are consistent with the theoretical prediction of the formation of Δ matter in neutron-rich matter at high compression.

Using data obtained through simultaneous measurements of $(\overrightarrow{p},p^{\prime })$ spin-transfer observables and $\left(\overrightarrow{p}{,p}^{\prime }\gamma \right)$ coincident spin observables, we have made a model-independent determination of the complete scattering amplitude for the 15.11 MeV, $1^{+},$ $T=1\mathrm{}$ state in ${}^{12}\mathrm{C}$ at an incident proton energy of 200 MeV, for four proton scattering angles ranging from ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=5.5\mathrm{}°–16.5°.$ At each angle, 16 different observables were determined, whereas only 11 independent quantities are required to specify the transition amplitude for this state. It had been shown previously that the set of observables measured span the allowed space; hence the system is overdetermined, which allowed us to extract, in a model-independent fashion, each of the individual spin-operator amplitudes that characterize the reaction. Additional insight into the physical mechanisms that drive this transition is obtained by mapping out the momentum-transfer dependence of these amplitudes. We also compare the magnitudes and phases determined for each of the spin-operator amplitudes to the predictions of calculations performed in both relativistic and nonrelativistic frameworks, and discuss the physics content of these comparisons.

We investigated the ${}^2\mathrm{H}(\overrightarrow{p},pp)n$ breakup reaction by measuring an angular distribution of the cross section and analyzing power in the $\mathrm{np}$ final-state interaction (FSI) at $E_{\overrightarrow{p}}=19\mathrm{}\mathrm{MeV}$ as a function of the $\mathrm{np}$ production angle. Kinematically complete measurements at 12 angular settings of detectors have been done. The observables around the exact FSI point were compared with predictions of four modern $\mathrm{NN}$ potentials, calculated for ${}^2\mathrm{H}\mathrm{}(n,np)n,$ i.e., without inclusion of the Coulomb interaction. The resulting good overall agreement between the data and theory indicates the smallness of three-nucleon force (3NF) effects as well as the insignificance of the Coulomb force for this particular configuration and energy. This conclusion is supported by results of three-nucleon (3N) Faddeev calculations performed with 2π-exchange Tucson-Melbourne 3NF with cutoff parameter adjusted individually for each $\mathrm{NN}$ interaction to fit the experimental triton binding.

In an attempt to clarify the situation regarding the low-lying structure of ${}^{10}\mathrm{Li}$, a spectroscopic measurement of the structure of ${}^{10}\mathrm{Li}$ with the ${}^9\mathrm{Be}{(}^9\mathrm{Be}{,}^8\mathrm{B}{)}^{10}\mathrm{Li}$ reaction at ${E(}^9\mathrm{Be})=40.1\mathrm{}(1)\mathrm{}$ MeV/nucleon was performed using the S800 spectrograph at Michigan State University. The data are fit best with a single p-wave resonance at $-S_n=0.500\mathrm{}\left(60\right)\mathrm{}\hspace{0.5em}\mathrm{MeV}$ with a width of $\Gamma =400\mathrm{}\left(60\right)\mathrm{}\hspace{0.5em}\mathrm{keV}$. No higher lying states were observed and there is no evidence of a state at $\sim 250\hspace{0.5em}\mathrm{keV}$ in the data. An excess strength at threshold was observed, but cannot be definitively attributed to a state.