A Semiclassical Approach to Fusion Reactions

The semiclassical method of Alder and Winther is generalized to study fusion reactions. As an illustration, we evaluate the fusion cross section in a schematic two-channel calculation. The results are shown to be in good agreement with those obtained with a quantal Coupled-Channels calculation. We suggest that in the case of coupling to continuum states this approach may provide a simpler alternative to the Continuum Discretized Coupled-Channels method.Comment: 6 pages, 1 figure, invited talk at the International Symposium "A new era of Nuclear Structure Physics", Niigata, Japan, Nov. 19-22 200

Transverse Isotropy in Identical Particle Scattering

It is pointed out that the cross section for the scattering of identical charged bosons is isotropic over a broad angular range around 90 degrees when the Sommerfeld parameter has a critical value, which depends exclusively on the spin of the particle. A discussion of systems where this phenomenon can be observed is presented.Comment: 8 pages, RevTeX format, 2 figures (.eps format

A study of local approximation for polarization potentials

We discuss the derivation of an equivalent \textit{l}-independent polarization potential for use in the optical Schr\"{o}dinger equation that describes the elastic scattering of heavy ions. Three diffferent methods are used for this purpose. Application of our theory to the low energy scattering of the halo nucleus $^{11}$Li from a $^{12}$C target is made. It is found that the notion of \textit{l}-independent polarization potential has some validity but can not be a good substitute for the \textit{l}-dependent local equivalent Feshbach polarization potential.Comment: 8 pages, 4 figure

Geometry of Borromean Halo Nuclei

We discuss the geometry of the highly quantal nuclear three-body systems composed of a core plus two loosely bound particles. These Borromean nuclei have no single bound two-body subsystem. Correlation plays a prominent role. From consideration of the $B(E1)$ value extracted from electromagnetic dissociation, in conjunction with HBT-type analysis of the two valence-halo particles correlation, we show that an estimate of the over-all geometry can be deduced. In particular we find that the opening angle between the two neutrons in $^{6}$He and $^{11}$Li are, respectively, $\theta_{nn} = {83^{\circ}}^{+20}_{-10}$ and ${66^{\circ}}^{+22}_{-18}$. These angles are reduced by about 12% to $\theta_{nn} = {78^{\circ}}^{+13}_{-18}$ and ${58^{\circ}}^{+10}_{-14}$ if the laser spectroscopy values of the rms charge radii are used to obtain the rms distance between the cores and the center of mass of the two neutrons. The opening angle in the case of $^{11}$Li is more than 20% larger than recently reported by Nakamura \cite{Nak06}. The analysis is extended to $^{14}$Be and the two-proton Borromean nucleus $^{17}$Ne where complete data is still not available. Using available experimental data and recent theoretical calculations we find, $\theta_{nn} = {64^{0}}^{+9}_{-10}$ and $\theta_{pp} = 110^{0}$, respectively.Comment: 5 pages, one figure, version to appear in PRC, Rapid Communication

The Impact of Ownership Structure and Board Characteristics on Earnings Quality: Evidence from Saudi Arabia

This paper investigates the impact of managerial and ownership structures on earnings quality in Saudi Arabia. The starting point was a literature review that was focused on earnings quality and its determinants. A study population was used when collecting the study data that consisted of all listed companies in the Saudi Stock Exchange during the period from 2019 to 2021, excluding financial sector firms. The final sample included 110 non-financial joint stock companies, the study results showed that managerial ownership has a positive and significant impact on earnings quality, while leverage has a negative and significant impact on earnings quality. Results showed a positive but non-significant impact for institutional ownership and board of directors’ size on earnings quality, the study results also showed a negative and non- significant impact for ownership concentration, board of directors’ independence, CEO duality, and corporate size on earnings quality. Finally, the study results will add to the accounting literature by helping stakeholders in understanding various determinants of earnings quality