This document provides an overview of first order calculations to model the decay of a Higgs boson into an electron-positron pair. It begins by defining the initial and final states as one-particle and two-particle states raised from the vacuum. It then uses the time evolution operator and Dyson expansion to first order to relate the initial and final states. Next, it expresses the Higgs, electron, and positron fields as operators that are split into positive and negative energy modes. Finally, it applies the field operators to the initial state to begin calculating the matrix element for this decay process.
4. We then proceed to split up the field operators into the positive and negative energy modes.
The Higgs boson π that is identified here as a real scalar field goes with a corresponding bosonic
field operator in the form given by
(12.1)
πΜ(π₯) = β« ππ(π
β ) (πβπππ₯
π(π
β ) + ππππ₯
πβ
(π
β ) )
where in short hand we have
(12.2)
β« ππ(π
β ) = β«
π3
π
β
β(2π)3
1
β2π0
π0
= π0
(π
β )
ππ₯ = π0
π₯0
β π
β β π₯
πππ‘πππ π πππππ‘π’ππ = β2
In (12.1) we take
(12.3)
πΜ+(π₯) = β« ππ(π
β ) πβπππ₯
π(π
β )
as the field operator in the positive energy mode, while in the negative energy mode we have
(12.4)
πΜβ(π₯) = β« ππ(π
β ) ππππ₯
πβ
(π
β )
We operate on the initial state vector (1) with the given field operator for the Higgs boson