%0 Conference Paper
%A Körner, J. G.
%T Helicity Amplitudes and Angular Decay Distributions
%N MITP-14-004
%C Hamburg
%I Deutsches Elektronen-Synchrotron, DESY
%M PUBDB-2015-05833
%M MITP-14-004
%M arXiv:1402.2787
%P 169-184
%D 2014
%X I discuss how to obtain angular decay distributions for sequentialcascade decays using helicity methods. The angular decay distributionsfollow from a reasonably simple master formula involving bilinearforms of helicity amplitudes and Wigner's d functions. I discussin some detail the issue of gauge invariance for off-shell gauge bosons.As a technical exercise I calculate the linear relation between thehelicity amplitudes and the invariant amplitudes of semileptonic andrare baryon decays. I discuss two explicit examples of angular decaydistributions for (i) the decay t→ b+W<sup>+</sup>(→ <i>l</i><sup>+</sup>ν<sub><i>l</i></sub>) (whichleads to the notion of the helicity fractions of the W<sup>+</sup>), and (ii)the sequential decay Λ<sub>b</sub>→Λ(→ pπ<sup>−</sup>)+J/ψ(→ <i>l</i><sup>+</sup><i>l</i><sup>−</sup>).T = Helicity Amplitudes and Angular Decay Distributions
%B Helmholtz International School on Physics of Heavy Quarks and Hadrons
%C 15 Jul 2013 - 28 Jul 2013, Dubna (Russia)
Y2 15 Jul 2013 - 28 Jul 2013
M2 Dubna, Russia
%K helicity: amplitude analysis (INSPIRE)
%K baryon: decay (INSPIRE)
%K gauge boson: off-shell (INSPIRE)
%K invariance: gauge (INSPIRE)
%K cascade decay (INSPIRE)
%F PUB:(DE-HGF)8 ; PUB:(DE-HGF)15
%9 Contribution to a conference proceedingsInternal Report
%R 10.3204/DESY-PROC-2013-03/Koerner
%U https://bib-pubdb1.desy.de/record/292120