TY  - CONF
AU  - Körner, J. G.
TI  - Helicity Amplitudes and Angular Decay Distributions
IS  - MITP-14-004
CY  - Hamburg
PB  - Deutsches Elektronen-Synchrotron, DESY
M1  - PUBDB-2015-05833
M1  - MITP-14-004
M1  - arXiv:1402.2787
SP  - 169-184
PY  - 2014
AB  - 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
T2  - Helmholtz International School on Physics of Heavy Quarks and Hadrons
CY  - 15 Jul 2013 - 28 Jul 2013, Dubna (Russia)
Y2  - 15 Jul 2013 - 28 Jul 2013
M2  - Dubna, Russia
KW  - helicity: amplitude analysis (INSPIRE)
KW  - baryon: decay (INSPIRE)
KW  - gauge boson: off-shell (INSPIRE)
KW  - invariance: gauge (INSPIRE)
KW  - cascade decay (INSPIRE)
LB  - PUB:(DE-HGF)8 ; PUB:(DE-HGF)15
DO  - DOI:10.3204/DESY-PROC-2013-03/Koerner
UR  - https://bib-pubdb1.desy.de/record/292120
ER  -