We present an extension of the recombination formalism to analyze the effects of variation of the hadron wavefunctions. The hadron spectra are sensitive to the shape of the wavefunctions. However, when we fit the wavefunction parameters to the physical observables, such as the average charge radius, the final spectra are very similar to one another. We discuss our numerical results in comparison with the published PHENIX and STAR data for the BNL Relativistic Heavy Ion Collider. In the hadron spectra, the recombination of thermal partons dominates at intermediate transverse momentum ($P_T=2\text{−}5$ GeV), and the fragmentation dominates at high $P_T(>5$ GeV). The yield ratios and the nuclear modification factors for various hadron species are also estimated and compared with the experimental data. We present a new prediction for $\overline{p}/p$ and $K^{-}/K^{+}$ ratios, including the jet quenching effects on the fragmentation mechanism.

We propose a new implementation of target mass corrections to nucleon structure functions which, unlike existing treatments, has the correct kinematic threshold behavior at finite $Q^2$ in the $x\to 1$ limit. We illustrate the differences between the new approach and existing prescriptions by considering specific examples for the $F_2$ and $F_L$ structure functions, and discuss the broader implications of our results, which call into question the notion of universal parton distribution at finite $Q^2$.

A search has been made for the ${}^6\mathrm{He}+{}^6\mathrm{He}$ and α + ${}^8\mathrm{He}$ decay of the molecular rotational band in ${}^{12}\mathrm{Be}$ using the ${}^{10}\mathrm{Be}$(${}^{14}\mathrm{C}$,${}^{12}\mathrm{Be}$${}^{*}$)${}^{12}\mathrm{C}$ reaction at 88.5 MeV. Although the α + ${}^6\mathrm{He}$ decay of ${}^{10}\mathrm{Be}$ was observed in the data set there is no evidence for the breakup of ${}^{12}\mathrm{Be}$. The cross-section upper limits for the ${}^{10}\mathrm{Be}$(${}^{14}\mathrm{C}$,${}^6\mathrm{He}$ ${}^6\mathrm{He}$)${}^{12}\mathrm{C}$ and ${}^{10}\mathrm{Be}$(${}^{14}\mathrm{C}$,α ${}^8\mathrm{He}$)${}^{12}\mathrm{C}$ reactions are 50 and 300 nb respectively.

The correlated-basis function theory is applied to the study of medium-heavy doubly-closed-shell nuclei with different wave functions for protons and neutrons and in the $\mathit{jj}$ coupling scheme. State-dependent correlations including tensor correlations are used. Realistic two-body interactions of Argonne and Urbana type, together with three-body interactions, have been used to calculate ground-state energies and density distributions of the ${}^{12}\mathrm{C}$, ${}^{16}\mathrm{O}$, ${}^{40}\mathrm{Ca}$, ${}^{48}\mathrm{Ca}$, and ${}^{208}\mathrm{Pb}$ nuclei.

We introduce a simple two-level boson model with the same energy surface as the Q-consistent interacting boson model Hamiltonian. The model can be diagonalized for large number of bosons and the results used to check analytical finite-size corrections to the energy gap and the order parameter in the critical region.

The ${}^{40}\mathrm{Ar}$($\overrightarrow{\gamma },{\gamma }^{\prime }$) photon scattering reaction was used to search for spin-flip $M1$ strength in ${}^{40}\mathrm{Ar}$. The nearly monochromatic, linearly polarized photon beam of HIγS, in an energy region from 7.7 to 11 MeV, was employed in this study. 28 dipole excitations were observed. The azimuthal intensity asymmetry indicated that all of these states were $E1$ except for the state at $E_x=9.757$ MeV. Shell-model calculations were used to interpret this state as one fragment of the spin-flip $M1$ strength in ${}^{40}\mathrm{Ar}$.

To study the conditions leading to the appearance of the threshold anomaly in systems involving weakly bound projectiles we measured elastic scattering cross sections for the ${}^7\mathrm{Li}+{}^{27}\mathrm{Al}$ system at ten different bombarding energies. The results were exhaustively analyzed using different optical model potentials. The similar behavior observed in all these analyses allows us to conclude that no threshold anomaly is found for the present system.

We have deduced the cross section for ${}^{237}\mathrm{U}$($n,f$) over an equivalent neutron energy range from 0 to 20 MeV using the surrogate ratio method. A 55 MeV ${}^4\mathrm{He}$ beam from the 88 inch cyclotron at Lawrence Berkeley National Laboratory was used to induce fission in the following reactions: ${}^{238}\mathrm{U}$$(\alpha ,{\alpha }^{\prime }f)$ and ${}^{236}\mathrm{U}$$(\alpha ,{\alpha }^{\prime }f)$. The ${}^{238}\mathrm{U}$ reaction was a surrogate for ${}^{237}\mathrm{U}$$(n,f)$, and the ${}^{236}\mathrm{U}$ reaction was used as a surrogate for ${}^{235}\mathrm{U}$$(n,f)$. Scattered α particles were detected in a fully depleted segmented silicon telescope array over an angle range of ${35}^{°}$ to ${60}^{°}$ with respect to the beam axis. The fission fragments were detected in a third independent silicon detector located at backward angles between ${106}^{°}$ and ${131}^{°}$.

The Coulomb interaction between the protons is included in the description of proton-deuteron scattering using the screening and renormalization approach in the framework of momentum-space integral equations. Two new calculational schemes are presented that confirm the reliability of the perturbative approach for treating the screened Coulomb interaction in high partial waves, used by us in earlier works.

The general properties of intrinsic energy correlations in the three-body continuum of Borromean halo nuclei are considered. A model that describes the system as a three-body $\alpha +n+n$ cluster structure and reproduces the experimentally known properties of ${}^6\mathrm{He}$ and ${}^6\mathrm{Li}$ is used to study low-lying resonances and soft modes. The intrinsic correlated structure of the ${}^6\mathrm{He}$ continuum reveals a unique structure for three-body $2_1^{+},2_2^{+},$ and $1_1^{+}$ resonances and a lack of resonant structure in soft dipole and monopole modes.

The low-energy level structure of the exotic Na isotopes ${}^{27,28,29}\mathrm{Na}$ has been investigated through β-delayed γ spectroscopy. Detailed level structure of ${}^{28,29}\mathrm{Na}$ has been obtained through $\beta \gamma$ and $\beta \gamma \gamma$ coincidence measurements. The low-lying levels populated in ${}^{27}\mathrm{Na}$ by β decay were found to corroborate well with the in-beam data from the literature. Half-lives of the parent nuclides, ${}^{27,28,29}\mathrm{Ne}$, were measured using β fragment as well as fragment $\beta \gamma$ coincidences and compared to previous measurements. The β-delayed one- and two-neutron emission branching probabilities have been obtained from the γ activities of the grand daughter nuclei. A comparison of the level schemes and the β-decay branching ratios is made with shell-model predictions, both with and without intruder configurations, to understand the transition from normal-dominant to intruder-dominant excitations in these neutron-rich nuclei approaching the island of inversion.

Noncentral collisions of ${}^{114}\mathrm{Cd}$ projectiles with ${}^{92}\mathrm{Mo}$ target nuclei at $E/A=50$ MeV are explored with an antisymmetrized molecular dynamics model. These collisions are found to be essentially binary in character with formation of an excited projectile-like fragment (PLF${}^{*}$) and targetlike fragment (TLF${}^{*}$). The average excitation energy deduced for the PLF${}^{*}$ and TLF${}^{*}$ saturates for midcentral collisions, $3.5\le b\le 6$ fm, with its magnitude depending on the cluster recognition time. For short cluster recognition times $(t=150\mathrm{fm}/c)$, an average excitation energy as high as ≈6 MeV is determined, indicating a short statistical lifetime for the fragments produced. Evidence for such a rapid deexcitation is observed in the present calculations.

The two- and three-charged-particle nuclear scattering problems are investigated in momentum space. The three-body equations with a short-range nuclear potential, a three-body force potential, and the long-range Coulomb potential are presented in a mathematically rigorous way within a generalized two-potential theory. To remove the serious singularity in the two- and three-body Coulomb problems in momentum space, we have proposed a novel boundary condition to the phase shift that arises from a potential difference, the so-called auxiliary potential (AP), between the Coulomb potential and the screened Coulomb one: $V^{\varphi }=V^C-V^R$. Furthermore, we point out the importance of the off-shell amplitude for the AP, by which one can uniquely obtain the two-body on-shell and off-shell Coulomb amplitude in momentum space. Therefore, this formulation is also useful for atomic systems, which is another benefit. It is recalled that the traditional phase-shift renormalization theory, in which the screened Coulomb amplitude is sandwiched by renormalized phase factors $e^{i\varphi }$, is not consistent with two-potential theory. Some ambiguities or misunderstandings of the traditional methods for handling the Coulomb problem are clarified. Finally, the three-body unitarity relation is proved for the amplitude generated from these three kinds of potential. Moreover, a generalized two-potential theory is presented. It is pointed out that the asymptotic three-body nuclear wave function with the Coulomb potential could not be written by a product of two individual wave functions ${\tilde{\psi }}_x(x){\tilde{\psi }}_y(y)$ defined in terms of Jacobi coordinates $x$ and $y$, respectively.

The half-lives and $\log \mathit{ft}$ values for the fourth-forbidden non-unique beta decays of the ground states of ${}^{113}\mathrm{Cd}$ and ${}^{115}\mathrm{In}$ were calculated using a transparent formulation for the ${\beta }^{-}$ transition amplitude. The microscopic quasiparticle-phonon model (MQPM) was used to calculate the initial and final states of the transitions. The corresponding wave functions were described as linear combinations of one- and three-quasiparticle configurations built in a realistic single-particle model space by using a realistic microscopic two-body interaction. The computed results for the $\log \mathit{ft}$ values and half-lives are reasonably close to the available experimental data.

The effect of nuclear deformation on the energy distributions of the Gamow-Teller strength is studied in neutron-deficient Hg, Pb, and Po even isotopes. The theoretical framework is based on a self-consistent deformed Skyrme Hartree-Fock mean field with pairing correlations between like nucleons in BCS approximation and residual spin-isospin interactions treated in the proton-neutron quasiparticle random-phase approximation. After a systematic study of the Gamow-Teller strength distributions in the low-excitation-energy region, relevant for ${\beta }^{+}$ decay, we have identified the best candidates to look for deformation signatures in their ${\beta }^{+}$-decay patterns. ${\beta }^{+}$ half-lives and total Gamow-Teller strengths $B({\mathrm{GT}}^{\pm })$ are analyzed as well.

The finite range Glauber model along with the Coulomb modification is used to analyze recently measured reaction cross sections with neutron-deficient Ga, Ge, As, Se, and Br isotopes as low-energy projectiles incident on ${}^{28}\mathrm{Si}$ target. The required input, namely the neutron and proton density distributions of the relevant projectiles and the target, are calculated in the relativistic mean-field framework. Though the calculations qualitatively agree with the experiment, on the average, slightly overestimate the cross sections. A phenomenological expression with a single parameter is proposed that consistently improves the agreement with the experiment.

In the isovector reaction, the sum rule for the spin dependent function $g_1$ which is related to the cross section of the photoproduction is derived. In the small $Q^2$ region, the sum rule is dominated by the low energy contribution and it tightly connects the resonance, the elastic, and the nonresonant contributions.

The two-photon exchange contribution to the single spin asymmetries with the spin orientation normal to the reaction plane is discussed for elastic electron-proton scattering in the equivalent photon approximation. In this case, the hadronic part of the two-photon exchange amplitude describes real Compton scattering (RCS). We show that in the case of the beam normal spin asymmetry this approximation selects only the photon helicity flip amplitudes of RCS. At low energies, we make use of unitarity and estimate the contribution of the $\pi N$ multipoles to the photon helicity flip amplitudes. In the Regge regime, the quasi-RCS (QRCS) approximation allows for a contribution from two-pion exchange, and we provide an estimate of such contributions.

A comparative study is performed of a deformed mean field theory, represented by the cranked Nilsson-Strutinsky (CNS) model and the spherical shell model. Energy spectra, occupation numbers, $B(E2)$ values, and spectroscopic quadrupole moments in the light $\mathit{pf}$-shell nuclei are calculated in the two models and compared. The result is also compared to available experimental data which are generally well described by the shell model. Although the Nilsson-Strutinsky calculation does not include pairing, both the subshell occupation numbers and quadrupole properties are found to be rather similar in the two models. It is also shown that “unpaired” shell model calculations produce energies similar to those from the CNS. The role of the pairing energy in the description of backbending and signature splitting in odd-mass nuclei is also discussed.

The relativistic mean field (RMF) approach describing the motion of independent particles in effective meson fields is extended by a microscopic theory of particle vibrational coupling. It leads to an energy dependence of the relativistic mass operator in the Dyson equation for the single-particle propagator. This equation is solved in the shell-model of Dirac states. As a result of the dynamics of particle-vibrational coupling we observe a noticeable increase of the level density near the Fermi surface. The shifts of the single-particle levels in the odd nuclei surrounding ${}^{208}\mathrm{Pb}$ and the corresponding distributions of the single-particle strength are discussed and compared with experimental data.