Search results for "Teoria electromagnètica"
showing 2 items of 2 documents
Technical memorandum: Mode classification in cylindrical surface waveguides
1987
A new method to analyse the TM-TE field structure of hybrid modes in cylindrical surface waveguides is proposed. This method, as well as others previously suggested, is applied to a dielectric-coated wire with an intervening airgap. Our results reveal that they cannot be classified into quasi-TM and quasi-TE modes. However, a scheme of mode designation is proposed, based more on mathematical properties than on the field structure.
Precise determination of the branching ratio of the neutral-pion Dalitz decay
2019
We provide a new value for the ratio $R={\Gamma(\pi^0\to e^+e^-\gamma(\gamma))}/{\Gamma(\pi^0\to\gamma\gamma)}=11.978(6)\times10^{-3}$, which is by two orders of magnitude more precise than the current Particle Data Group average. It is obtained using the complete set of the next-to-leading-order radiative corrections in the QED sector, and incorporates up-to-date values of the $\pi^0$-transition-form-factor slope. The ratio $R$ translates into the branching ratios of the two main $\pi^0$ decay modes: $\mathcal{B}(\pi^0\to\gamma\gamma)=98.8131(6)\,\%$ and $\mathcal{B}(\pi^0\to e^+e^-\gamma(\gamma))=1.1836(6)\,\%$.