163 research outputs found
Two-loop electroweak top corrections: are they under control?
The assumption that two-loop top corrections are well approximated by the
contribution is investigated. It is shown that in the case of
the ratio neutral-to-charged current amplitudes at zero momentum transfer the
terms are numerically comparable to the
contribution for realistic values of the top mass. An estimate of the
theoretical error due to unknown two-loop top effect is presented for a few
observables of LEP interest.Comment: 13 pages, LaTeX using equations, doublespace, cite macros. Hard
copies of the paper including one figure are available from
[email protected]
The Landau Distribution for Charged Particles Traversing Thin Films
The Landau distribution as well as its first and second momenta are well
suited for describing the energy loss of charged particles traversing a thin
layer of matter. At present, just rational approximations and asymptotic
expressions for these functions were obtained. In this paper we present a
direct calculation of the integral representation of these functions obtaining
perturbative and nonperturvative solutions expressed in terms of fast
convergent series. We also provide a simple numerical algorithm which allows to
control speed and precision of the results. The testing runs have provided, in
reasonable computing times, correct results up to 13-14 significant digits on
the density and distribution functions and 9-10 on the first and second
momenta. If necessary, this accuracy could be improved by adding more
coefficients to the algorithm.Comment: 29 pages, 4 Table
Radiative decays of mesons in the NJL model
We revisit the theoretical predictions for anomalous radiative decays of
pseudoscalar and vector mesons. Our analysis is performed in the framework of
the Nambu-Jona-Lasinio model, introducing adequate parameters to account for
the breakdown of chiral symmetry. The results are comparable with those
obtained in previous approaches.Comment: 19 pages incl. 4 figure
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