Higher-order Polarization Research Articles

Laser spectroscopy of ( nu =0,R

Rydberg states of ${\mathrm{H}}_{2}$ consisting of a 10F or 10G electron bound to the \ensuremath{\nu}=0,R=1 state of ${\mathrm{H}}_{2}^{+}$ are studied using Doppler-tuned laser spectroscopy of Rydberg-Rydberg transitions. The positions of all such states are measured to a precision of better than 0.01 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and are compared with the predictions of the polarization model. The polarization model is derived from first principles. Nonadiabatic corrections to the dipole polarization energies, calculated for the first time, are found to be expressible in terms of the ${S}_{\mathrm{\ensuremath{-}}3}$-moment functions of ${\mathrm{H}}_{2}^{+}$. Higher-order adiabatic polarization energies are estimated from calculated higher-order ${\mathrm{H}}_{2}^{+}$ polarizabilities.

Nonlinear relations between observables in the scattering of spinor particles and the direct reconstruction of the scattering matrix

Nonlinear relations between observables in the elastic scattering of two nonidentical particles are obtained, namely 17 relations expressing the components of higher-order polarization tensors in terms of lower-order ones (of degree $d\ensuremath{\le}2$) and 8 relations between the 19 simplest experiments. The relations are used to discuss the completeness of various optimal sets of experiments and to perform a "semidirect" reconstruction of the $\mathrm{np}$ scattering amplitudes at ${E}_{\mathrm{lab}}=425$ MeV, ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}=65\ifmmode^\circ\else\textdegree\fi{}$ (from data points supplemented by "data" generated from a phase-shift analysis).

Exchange-Correlation Effects on the Higher-Order Polarizations of an Electron Gas

Exchange-Correlation Effects on the Higher-Order Polarizations of an Electron Gas

Measurement of higher-order corrections to stopping power for relativistic Ne, Ar, and Fe beams

Measurements of range of 600 MeV/amu /sup 20/Ne, /sup 40/Ar, and /sup 56/Fe in a variety of absorbers have been made to test the accuracy of the higher-order Mott, Bloch, and polarization correction terms to the Bethe expression of stopping power. These corrections give an acceptable (<2sigma) fit to energies determined by time-of-flight methods. A dramatically improved (<1sigma) fit follows if the relativistic Bloch term has half its currently calculated magnitude.

Vacuum Polarization in Heavy-Ion Collisions

The results of a study on vacuum polarization, orders $\ensuremath{\alpha}{(Z\ensuremath{\alpha})}^{n}$, $n&gt;~3$, for large-$Z$ systems encountered in heavy-ion collisions are presented. It is shown that the higher-order vacuum polarization cannot prevent the $1{S}_{\frac{1}{2}}$ state from reaching the lower continuum, $E=\ensuremath{-}{m}_{e}{c}^{2}$, for some critical charge ${Z}_{\mathrm{cr}}\ensuremath{\sim}170$. In addition, the stability and localization of a heliumlike system for $Z&gt;{Z}_{\mathrm{cr}}$ is demonstrated.

Generation of Vacuum-Ultraviolet and Soft—X-Ray Radiation Using High-Order Nonlinear Optical Polarizabilities

The harmonic or sum-frequency power generated in the last coherence length of a low-density atomic species is calculated subject to the condition that the applied electric field be bounded by the multiphoton absorption or ionization limit. It is shown that higher-order polarizations may equal or exceed lower-order polarizations. Calculations are given for generation at 1773 and 1064 \AA{} in Xe, and at 236, 169, and 177 \AA{} in ${\mathrm{Li}}^{+}$.

Higher-Order Vacuum Polarization Corrections in Muonic Atoms

Higher-Order Vacuum Polarization Corrections in Muonic Atoms

Higher-Order Vacuum Polarization Corrections in Muonic Atoms

In view of the recently reported discrepancies between theoretical calculations and accurate experimental measurements of muonic x-ray energies for several elements in the energy range 150-440 keV, we have recalculated the vacuum polarization corrections. Our results reduce, but do not eliminate, the discrepancies. We discuss the effects of a possible anomalous coupling of the muon to a speculative scalar meson of the type suggested by Weinberg.

Test of quantum-electrodynamical corrections in muonic atoms

Energies of the 5g-4f muonic X-rays have been measured in natHg and 203Tl with an accuracy of about 25 eV. They are found to be smaller than theoretical energies including recently revised calculations of higher-order vacuum polarization, by about two standard deviations.

Higher-order core polarization contributions to effective interactions

The perturbation theory calculation of the core-polarization contribution to effective interactions in mass 18 nuclei is carried to higher order, and it is shown that the perturbation series appears to diverge. It is argued, by analogy with nuclear matter results, that all three-body contributions to the core polarization must be treated together.