JoePhysicsNut
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I'd just like to clarify something I read on Wikipedia:
"The branching ratio of the common purely leptonic tau decays are:
17.82% for decay into a tau neutrino, electron and electron antineutrino;
17.39% for decay into a tau neutrino, muon and muon antineutrino.
The similarity of values of the two branching ratios is a consequence of lepton universality."
Just to be clear, lepton universality insures the couplings of tau to mu and electron are identical, however, there is a slight difference between the BRs and cross sections due to the availability of phase space. BR_mu is slighly less than BR_el because the mu is heavier so the density of states term in the cross section expression is smaller. Is this correct?
"The branching ratio of the common purely leptonic tau decays are:
17.82% for decay into a tau neutrino, electron and electron antineutrino;
17.39% for decay into a tau neutrino, muon and muon antineutrino.
The similarity of values of the two branching ratios is a consequence of lepton universality."
Just to be clear, lepton universality insures the couplings of tau to mu and electron are identical, however, there is a slight difference between the BRs and cross sections due to the availability of phase space. BR_mu is slighly less than BR_el because the mu is heavier so the density of states term in the cross section expression is smaller. Is this correct?