No abstract

Darwin-Foldy nuclear-size corrections in electronic atoms and nuclear radii are discussed from the nuclearphysics perspective. The interpretation of precise isotope-shift measurements is formalism dependent, and care must be exercised in interpreting these results and those obtained from relativistic electron scattering from nuclei. We strongly advocate that the entire nuclear-charge operator be used in calculating nuclear-size corrections in atoms rather than relegating portions of it to the nonradiative recoil corrections. A preliminary examination of the intrinsic deuteron radius obtained from isotope-shift measurements suggests the presence of small meson-exchange currents ͑exotic binding contributions of relativistic order͒ in the nuclear charge operator, which contribute approximately 1 2 %.

The problem of scattering in one dimension by a potential which consists of N identical cells is solved in a transparent manner. The N-cell transmission and reflection amplitudes are expressed in terms of the single-cell amplitudes and the Bloch phase. As examples the results are applied to a row of delta-function potentials, and to a row of square wells, and it is shown that these expressions provide an immediate understanding of the results of detailed calculations.

We consider a Bose-Einstein condensate in a double-well potential undergoing a dynamical transition from the regime of Josephson oscillations to the regime of self-trapping. We analyze the statistical properties of the ground state (or the highest excited state) of the Hamiltonian in these two regimes for attractive (repulsive) interactions. We demonstrate that it is impossible to describe the transition within the mean-field theory. In contrast, the transition proceeds through a strongly correlated delocalized state, with large quantum fluctuations, and spontaneous breaking of the symmetry.

No abstract