89 research outputs found
The pionic beta decay in chiral perturbation theory
Within the framework of chiral perturbation theory with virtual photons and
leptons, we present an updated analysis of the pionic beta decay including all
electromagnetic contributions of order e**2 p**2. We discuss the extraction of
the Cabibbo-Kobayashi-Maskawa matrix element |Vud| from experimental data. The
method employed here is consistent with the analogous treatment of the Kl3
decays and the determination of |Vus|.Comment: 8 pages, 1 figure, latex file, uses EPJC macro
The CP-violating asymmetry in K_L -> pi+ pi- e+ e-
We update the theoretical analysis of the CP-violating asymmetry in the decay
K_L -> pi+ pi- e+ e-, relying on chiral perturbation theory and on the most
recent phenomenological information. With the experimentally determined
magnetic amplitude and branching ratio as input, the asymmetry can be
calculated with good accuracy. The theoretical interpretation of the sign of
the asymmetry is discussed.Comment: 11 page
Low energy electron energy-loss spectroscopy of CFâX (X=Cl,Br)
We report threshold electron energy-loss spectra for the fluorohalomethanes CFCâX (X=Cl,Br). Measurements were made at incident electron energies of 30 and 100 eV in energy-loss range of 4-14 eV, and at scattering angles of 4 degrees and 15 degrees. Several new electronic transitions are observed which are ascribable to excitation of low-lying states as well as are intrinsically overlapped in the molecules themselves. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-section measurements, high-energy scattering spectra, and ab initio molecular orbital calculations. The calculated potential curves along the C-X bond show repulsive nature, suggesting that these transitions may lead to dissociation of the C-X bond. The present results are also compared with the previous ones for CFâH, CFâ, and CFâI.This work was performed with the support and under the
auspices of the CUP, the IAEAâs Co-ordinated Research Program,
MEXT, and JAEA. One of the authors C.M. had
been also thankful to the Japan Society for Promotion of
Science for financial support under Grant No. P04064. One
of the authors L.P. also acknowledges partial support by the
Academic Frontier Program of MEXT. One of the authors
H.C. acknowledges the support from the Korea Research
Foundation 2006-311-C00031
Convergence of CI single center calculations of positron-atom interactions
The Configuration Interaction (CI) method using orbitals centered on the
nucleus has recently been applied to calculate the interactions of positrons
interacting with atoms. Computational investigations of the convergence
properties of binding energy, phase shift and annihilation rate with respect to
the maximum angular momentum of the orbital basis for the e^+Cu and PsH bound
states, and the e^+-H scattering system were completed. The annihilation rates
converge very slowly with angular momentum, and moreover the convergence with
radial basis dimension appears to be slower for high angular momentum. A number
of methods of completing the partial wave sum are compared, an approach based
on a Delta X_J = a/(J + 1/2)^n + b/(J + 1/2)^(n+1) form (with n = 4 for phase
shift (or energy) and n = 2 for the annihilation rate) seems to be preferred on
considerations of utility and underlying physical justification.Comment: 23 pages preprint RevTeX, 11 figures, submitted to PR
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