Search results for "Born approximation"
showing 5 items of 55 documents
Measurement of the D∗± cross section in two photon collisions at LEP
1995
Abstract The inclusive production of D ∗± mesons in photon-photon collisions has been measured by the Aleph experiment at LEP with a beam energy of 45 GeV. The D ∗+ are detected in their decay to D 0 π + with the D 0 observed in three separate decay modes: (1) K − π + , (2) K − π + π 0 and (3) K − π + π − π + , and analagously for the D ∗− modes. A total of 33 events was observed from an integrated luminosity of 73 pb −1 which corresponds to a cross section for Σ( e + e − → e + e − D ∗± X ) of 155 ± 33 ± 21 pb. This result is compatible with both the direct production γγ → c c in the Born approximation and with a more complete calculation which includes both radiative QCD corrections and co…
Longitudinal contribution to the alignment polarization of quarks produced in e + e - -annihilation: an O (α s ) effect
1996
We calculate the longitudinal contribution to the alignment polarization Pl of quarks produced in e+e− annihilation. In the Standard Model, the longitudinal alignment polarization vanishes at the Born term level and thus receives its first non-zero contribution from the O(αs) tree graph process. We provide analytical and numerical results for the longitudinal alignment polarization of massless and massive quarks, in particular for the recently discovered top quark.
Potentials with SuppressedS-Wave Phase Shift at Low Energies
1972
These results are valid for arbitrary range and depths of the potentials here studied. In spite of the fact that for the general solution we have worked only with a particular radial dependence, for .which an explicit solution for the phase shifts can be written down, it seems plausible that the results have a more general validity. With this generalization in mind, we show that for general shapes of the radial dependence, the phase shifts in Born approximation present the momentum dependence described above. The origin of our results become transparent in this Born approximation treatment. We consider a velocity dependent potential of the form 1 )
Non-Markovian dynamics of interacting qubit pair coupled to two independent bosonic baths
2009
The dynamics of two interacting spins coupled to separate bosonic baths is studied. An analytical solution in Born approximation for arbitrary spectral density functions of the bosonic environments is found. It is shown that in the non-Markovian cases concurrence "lives" longer or reaches greater values.
Many-body Green's function theory for electron-phonon interactions: ground state properties of the Holstein dimer
2015
We study ground-state properties of a two-site, two-electron Holstein model describing two molecules coupled indirectly via electron-phonon interaction by using both exact diagonalization and self-consistent diagrammatic many-body perturbation theory. The Hartree and self-consistent Born approximations used in the present work are studied at different levels of self-consistency. The governing equations are shown to exhibit multiple solutions when the electron-phonon interaction is sufficiently strong whereas at smaller interactions only a single solution is found. The additional solutions at larger electron-phonon couplings correspond to symmetry-broken states with inhomogeneous electron de…