1 research outputs found
Short and Long Distance Effects in the Decay
We calculate the radiative corrections to the decays and
\pi \to l \nu_\l, where the meson is or and the lepton is
or . We perform a complete calculation, which includes internal
bremsstrahlung and structure dependent radiation in the radiative decays and
point meson, hadronic structure dependent and short distance contributions in
the virtual corrections. Our result for the radiative correction to the ratio
is
\delta R_{\tau/\pi} = \left(0.16_{\T - 0.14}^{\T+0.09}\right) \%. For the
ratio , we
obtain \delta R_{\tau/K } = \left(0.90_{\T - 0.26}^{\T + 0.17}\right) \%. For
completeness we have also calculated the ratio of the electronic and muonic
decay modes of the pion.Comment: 39 pages, Latex [19 figures, not included]: A complete postscript
file, including figures, is available via anonymous ftp at
ttpux2.physik.uni-karlsruhe.de (129.13.102.139) as /pub/ttp94-05/ttp94-05.ps,
Local preprint# TTP94-5. Revised version: In the previous version of this
paper we used a relative sign between internal bremsstrahlung and
the structure dependent radiation. However, as explained in TTP93-1A
(hep-ph/940538), we now believe that is the physical choic