Coupled-channels three-body calculations of an $I=1/2,J^{\pi }=0^{-}$ $\overline{K}\mathit{NN}$ quasibound state in the $\overline{K}\mathit{NN}\text{−}\pi \Sigma N$ system were performed and the dependence of the resulting three-body energy on the two-body $\overline{K}N\text{−}\pi \Sigma$ interaction was investigated. Earlier results of binding energy $B_{K^{-}\mathit{pp}}~50\text{−}70$ MeV and width ${\Gamma }_{K^{-}\mathit{pp}}~100$ MeV are confirmed [N. V. Shevchenko et al., Phys. Rev. Lett. 98, 082301 (2007)]. It is shown that a suitably constructed energy-independent complex $\overline{K}N$ potential gives a considerably shallower and narrower three-body quasibound state than the full coupled-channels calculation. Comparison with other calculations is made.

Adiabatic fusion barriers are studied within the static Hartree-Fock method with the effective Skyrme interactions SkM${}^{*}$ and SLy6. The problem of kinetic energy of the relative motion becoming spurious for separate fragments, relevant for both fusion and fission barriers, is discussed in some detail. Also discussed are the specific assumptions necessary to compensate for the nonuniqueness of the static method. Barriers obtained with two forces agree to within 2 MeV and seem nearly decoupled from errors in binding energies, specific to each force. For a number of reactions, comparisons are made with experimental estimates of barriers and barriers calculated with the frozen densities. The adiabatic barriers are generally lower than the experimental estimates. The offset amounts to less than 3 MeV in lighter systems and varies between 0 and $~10$ MeV in heavy ones. Compared to the data, the frozen-density barriers in heavy systems do not seem more realistic than ours, perhaps, except for tip collisions with deformed heavy targets. We also calculate HF energy surfaces for three heavy systems, looking for a relation between adiabatic potential and the fusion hindrance at large $Z_T{Z}_P$. One can see a link between quasifission and the force opposing fusion, acting inside the Coulomb barrier. One surface illustrates the identity of the adiabatic fusion barrier with the fission saddle of a compound nucleus.

The evolution of anisotropy in momentum and coordinate space of the parton system produced in relativistic heavy-ion collisions is discussed within the free-streaming approximation. The momentum distribution evolves from the prolate shape (elongated along the beam) to the oblate one (squeezed along the beam). At the same time, the eccentricity in coordinate space, which occurs at finite values of impact parameter, decreases. It is argued that the parton system reaches local thermodynamic equilibrium before the momentum distribution becomes oblate.

We investigate the role of lifetime effects from resonances and emission duration tails in femtoscopy at the BNL Relativistic Heavy Ion Collider in two blast-wave models. We findthe non-Gaussian components compare well with published source imaged data, but the valueof $R_{\mathrm{out}}$ obtained from Gaussian fits is not insensitive to the non-Gaussian contributions when realistic acceptance cuts are applied to models.

Our paper aims at providing an answer to the question of whether one can reliably describe the properties of the most important spin-isospin nuclear excitations by using the available nonrelativistic Skyrme energy functionals. Our method, which has been introduced in a previous publication devoted to the isobaric analog states, is the self-consistent quasiparticle random-phase approximation (QRPA). The inclusion of pairing is instrumental for describing a number of experimentally measured spherical systems which are characterized by open shells. We discuss the effect of isoscalar and isovector pairing correlations. Based on the results for the Gamow-Teller resonance in ${}^{90}\mathrm{Zr}$, ${}^{208}\mathrm{Pb}$, and a few Sn isotopes, we draw definite conclusions on the performance of different Skyrme parametrizations, and we suggest improvements for future fits. We also use the spin-dipole resonance as a benchmark of our statements.

Superdeformed states in light $N=Z$ nuclei are studied by means of the self-consistent cranking calculation (i.e., the P+QQ model based on the cranked Hartree-Fock-Bogoliubov method). Analyses are given for two typical cases of superdeformed bands in the $A\simeq 40$ mass region, that is, bands where backbending is absent (${}^{40}\mathrm{Ca}$) or present (${}^{36}\mathrm{Ar}$). Investigations are carried out particularly for the following points: cross-shell excitations in the $\mathit{sd}$ and $\mathit{pf}$ shells; the role of the $g_{9/2}$ and $d_{5/2}$ orbitals; the effect of nuclear pairing; and the interplay between triaxiality and band termination.

We present phenomenological formulas for virtual photon emission rates from a thermalized quark-gluon plasma (QGP) that include bremsstrahlung and annihilation with scattering (AWS) mechanisms along with the Landau-Pomeranchuk-Migdal (LPM) effects. For this purpose we follow the approach of generalized emission functions (GEF) for virtual photon emission, we showed earlier for a fixed temperature and strong coupling constant. In the present work, we extend the LPM calculations for several temperatures and strong coupling strengths, photon energies ($q_0)$, photon mass ($Q^2$), and quark energies ($p_0$). We generalize the dynamical scaling variables, $x_T,x_L$, for bremsstrahlung and AWS processes that are now functions of variables $p_0,q_0,Q^2,T,{\alpha }_s$. The GEF introduced earlier, $g_T^b,g_T^a,g_L^b,g_L^a$, are also generalized for any temperatures and coupling strengths. From this, the imaginary part of the photon polarization tensor as a function of photon mass and energy has been calculated as a one-dimensional integral over these GEF and parton distribution functions in the plasma. By fitting these polarization tensors obtained from GEF method, we obtained a phenomenological formula for virtual photon emission rates as a function of $\{q_0,Q^2,T,{\alpha }_s\}$ that includes bremsstrahlung and AWS mechanisms with LPM effects.

We present a comprehensive study of event-by-event multiplicity fluctuations in nucleon-nucleon and nucleus-nucleus interactions from the BNL Alternating Gradient Synchrotron/GSI Facility for Antiproton and Ion Research to BNL Relativistic Heavy Ion Collider energies within the ultrarelativistic quantum molecular dynamics transport approach. The scaled variances of negative, positive, and all charged hadrons are analyzed. The scaled variance in central Pb+Pb collisions increases with energy and behaves similar to inelastic $p+p$ interactions. We find a nontrivial dependence of multiplicity fluctuations on the rapidity and transverse-momentum interval used for the analysis and on the centrality selection procedure. Quantitative predictions for the NA49 experiment are given, taking into account the acceptance of the detector and the selection procedure of central events.

Based on a Langevin equation coupled with a statistical decay model, we explore the role of angular momentum in probing nuclear dissipation by calculating the excess of the evaporation residue cross section of the ${}^{200}\mathrm{Pb}$ nucleus over that predicted by the standard statistical model as a function of nuclear dissipation strength. Calculations show that high angular momentum not only enhances the dissipation effects on the excess of the evaporation residues substantially but also increases the sensitivity of this excess to the nuclear dissipation strength significantly. These results suggest that on the experimental side, to accurately obtain the information of nuclear dissipation inside the saddle point by measuring the evaporation residue cross section (or the fission cross section), it is best to populate those compound systems with high spins.

We present an exploratory study consisting in the formulation of a relativistic quantum mechanics to describe few-nucleon systems at low energy, starting from the quantum field theoretical chiral Lagrangian involving pions and nucleons. To this aim we construct a Bakamjian-Thomas mass operator and perform a truncation of the Fock space that respects at each stage the relativistic covariance. Such a truncation is justified, at sufficiently low energy, in the framework of a systematic chiral expansion. As an illustration we discuss the bound-state observables and low-energy phase shifts of nucleon-nucleon and pion-nucleon scattering at the leading order of our scheme.

We measured the differential cross section and the spin correlation parameter $C_{\mathit{yy}}$ of the $\overrightarrow{p}+\overrightarrow{{}^3\mathrm{He}}$ elastic backward scattering at 200, 300, and 400 MeV at $\theta ={180}^{°}$ in the center-of-mass frame to study the mechanism of the reaction and to examine the validity of the ${}^3\mathrm{He}$ wave functions based on two different realistic two-body forces. This is the first measurement of the spin correlation parameter $C_{\mathit{yy}}$ of the $\overrightarrow{p}+\overrightarrow{{}^3\mathrm{He}}$ EBS at intermediate energies. The experimental results were compared with few-body calculations, including three reaction mechanisms: two-nucleon-pair exchange, pion exchange, and direct $\mathit{pp}$ scattering. It was found that few-body calculations describe the differential cross-section data reasonably well. The spin correlation parameter $C_{\mathit{yy}}$ shows clear evidence for the two-nucleon-pair exchange processes in the reaction, demonstrating that the spin observables are helpful for deeper understanding of the reaction mechanism.

We present ab initio calculations for ${}^3\mathrm{H}$, ${}^4\mathrm{He}$, ${}^{16}\mathrm{O}$, and ${}^{40}\mathrm{Ca}$ based on two-nucleon low-momentum interactions $V_{\mathrm{low}k}$ within coupled-cluster theory. For ${}^3\mathrm{H}$ and ${}^4\mathrm{He}$, our results are within 70 and 10 keV of the corresponding Faddeev and Faddeev-Yakubovsky energies. We study in detail the convergence with respect to the size of the model space and the single-particle basis. For the heavier nuclei, we report practically converged binding energies and compare with other approaches.

The Gamow-Teller transition operator is written as a polynomial in the dipole proton-neutron and quadrupole charge-conserving quasiparticle random-phase approximation boson operators, using the prescription of the boson expansion technique. Then, the $2\nu \beta \beta$ process ending on the first $2^{+}$ state in the daughter nucleus is allowed through one-, two-, and three-boson states describing the odd-odd intermediate nucleus. The approach uses a single particle basis that is obtained by projecting out the good angular momentum from an orthogonal set of deformed functions. The basis for mother and daughter nuclei may have different deformations. The GT transition amplitude as well as the half-lives were calculated for 18 transitions. Results are compared with the available data as well as with the predictions obtained with other methods.

The energy spectra of neutrons, protons, and α-particles have been measured from the $d+$${}^{59}\mathrm{Co}$ and ${}^3\mathrm{He}+{}^{58}\mathrm{Fe}$ reactions leading to the same compound nucleus, ${}^{61}\mathrm{Ni}$. The experimental cross sections have been compared to Hauser-Feshbach model calculations using different input level density models. None of them have been found to agree with experiment. It manifests the serious problem with available level density parametrizations especially those based on neutron resonance spacings and density of discrete levels. New level densities and corresponding Fermi-gas parameters have been obtained for reaction product nuclei such as ${}^{60}\mathrm{Ni}$, ${}^{60}\mathrm{Co}$, and ${}^{57}\mathrm{Fe}$.

The exact relativistic form for the β decay endpoint spectrum is derived and presented in a simple factorized form. We show that our exact formula can be well approximated to yield the endpoint form used in the fit method of the KATRIN Collaboration. We also discuss the three-neutrino case and how information from neutrino oscillation experiments may be useful in analyzing future β decay endpoint experiments.

Theoretical α decay half-lives of the heaviest odd-$Z$ nuclei are calculated using the experimental $Q_{\alpha }$ value. The barriers in the quasimolecular shape path are determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulas. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time. Predictions are provided for the α decay half-lives of other superheavy nuclei within the GLDM and VSS approaches using the recent extrapolated $Q_{\alpha }$ of Audi, Wapstra, and Thibault [Nucl. Phys. A729, 337 (2003)], which may be used for future experimental assignment and identification.

The unusual temperature behavior of the entropy of the antiferromagnetic (AFM) spin state in symmetric nuclear matter with the Gogny D1S interaction, being larger at low temperatures than the entropy of nonpolarized matter, is related to the dependence of the entropy on the effective masses of nucleons in a spin polarized state. The corresponding conditions for comparing the entropies of the AFM and nonpolarized states in terms of the effective masses are formulated, including the low and high temperature limits. It is shown that the unexpected temperature behavior of the entropy of the AFM spin state at low temperatures is caused by the violation of the corresponding low-temperature criterion.

The storage of ultracold neutrons (UCN) in a combined magnetic, gravitational, and material trap is described. Wall materials investigated were diamondlike carbon (DLC) coatings on solid and flexible foil substrates as well as beryllium coatings on solid substrates. The loss coefficient per wall collision, η, and the depolarization probability β were measured simultaneously as a function of temperature (from 70 to 400 K) and energy (from 30 to 80 neV). The results at 70 K are $\eta =(0.7\pm 0.1)\times {10}^{-4},\beta =(15.4\pm 1.0)\times {10}^{-6}$ for DLC on polyethyleneterephtalate (PET) foil and $\eta =(1.7\pm 0.1)\times {10}^{-4},\beta =(0.7\pm 0.3)\times {10}^{-6}$ for DLC on aluminum foil. At room temperature the loss coefficients are larger by a factor of about 2 whereas the depolarization probabilities are found to be independent of temperature. The corresponding values for Be at room temperature are $\eta ~5\times {10}^{-4},\beta ~10\times {10}^{-6}$. The DLC results for β and for the temperature-dependent part of the loss coefficient, ${\eta }_T$, are interpreted in terms of incoherent scattering by hydrogen. The hydrogen admixture was measured independently by elastic recoil detection analysis to be about $1\times {10}^{16}$ atoms/cm${}^2$. The data do not support the hypothesis of hydrogen being chemically bound within the top layers of the DLC. Using two different models with a thin waterlike film on top of the substrate we obtain consistency between the temperature-dependent loss contribution and the measured hydrogen contamination.