Alright I'm not sure if this question is too speculative but here goes:
So in my graduate days I remember wishing I could put some kind of bounds on the S-matrix. I came to understanding that one of the problems was there was no other way to talk about the creation and annihilation operator in than the standard method in bra-ket notation. Due to this I decided to focus on creating my own formulation of them in Quantum Mechanics. I did (partially) succeed: https://mathoverflow.net/questions/301699/can-one-calculate-the-following-operator
One can define a creation operator:
A†|n⟩=|n+1⟩
In fact,
A†=|2⟩⟨1|+|3⟩⟨2|+|4⟩⟨3|+…
The
quantum mechanical creation operator is
ˆA†≤ˆa†
Taken from the answer (but edited due notation consistency error):
... we interpret |x⟩⟨y| as a rank 1 operator. In particular, ˆn is a coisometry which takes the orthonormal set {|n⟩,|2n⟩,|3n⟩,…} to the standard basis {|1⟩,|2⟩,|3⟩,…}. The "rational operator" ˆmn takes the basis vector |kn⟩ to |km⟩ when kn is an integer...
Now we make our reformulation:
(ˆ1−A†)−1=(∑0<R≤1ˆR)†
where
(∑0<R≤1ˆR) represents the sum of all rational operators whose corresponding rational number is less than or equal to
1.
Assuming the math somehow works itself out (?) Would a reformulation of the creation and annihilation operator help me in the endeavour of "bounding the S-matrix"? Have other people tried similar games for the similar purposes?