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  Successful reformulation of Path Integral Method?

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Question
The following is an attempt to reformulate Feynman's path integral formulation. Is this correct? Can this be made rigorous?  What is the radius of convergence? 

Proof
Let's think about Feynman's Path Integral Formulation of Quantum Mechanics.

A=xi|eiHdt|xf

Splitting into infinitesimally many δt:

A=xi|jeiHδtj|xf

Inserting infinitely many (N1) identity operators of the form |xtkxtk|xtk

A=xi|eiHδtj(N1j=1|xtjxtj|dxtjeiHδtj)|xf

Now, we stop at this step and pull out a random xtk:

A=xi|eiHδtj(jk|xtjxtj|dxtjeiHδtj)|xfxtk1|eiHδtk|xtkxtk|eiHδtk|xtk+1dxtkdxtk1dxtk+1

Adding over all possible tk's

NA=kxi|eiHδtj(jk|xtjxtj|dxtjeiHδtj)|xfxtk1|eiHδtk|xtkxtk|eiHδtk|xtk+1dxtkdxtk1dxtk+1

Since, k is just a dummy index we remove them (with δtl=δtm where l and m are arbitrary)  and proceed to use Nδt=tfti=T (where tf is the final time and ti is the initial time):

TA=k(xi|eiHδtj(jk|xtjxtj|dxtjeiHδtj)|xfxtk1|eiHδtk|xtkxtk|eiHδtk|xtk+1dxtk)δtkdxtk1dxtk+1

We make the redefinition:

(jk|xtjxtj|dxtjeiHδtj)=ak

Now, swapping the summation and the 2 integrals

TA=N1k=1akxtk1|eiHδtk|xtkxtk|eiHδtk|xtk+1dxtkδtkdxtk1dxtk+1

Evaluating the δtk integral first using this:

TA=k=1lims1akks×1ζ(s)tftixtk1|eiHδtk|xtkxtk|eiHδtk|xtk+1δtkdxtkdxtk1dxtk+1

Closed by author request
asked Oct 1, 2020 in Mathematics by Asaint (90 points) [ no revision ]
closed Oct 2, 2020 by author request

Partial answer: It deppends a lot on what is H. First try with harmonic oscilators... and do all the path...

Something that can be very useful for you are the next references:

If you are interested in rigorous formulations of path integral method, there are a lot, but Sergio Albeverio work on path integrals for QM is great, his book with Raphael Høegh-Krohn "Mathematical Theory of Feynman Path Integrals" is very good.

Also, path integral for QM has been done rigorous in a lot of instances, what's more messy is path integral in interacting QFTs.

Rivasseau book "from perturbative to constructive renormalization" and Glimm & Jaffe "quantum physics a functional integral point of view" are also great. They use a lot Cluster Expansion methods.

There are also a bit of nice papers by Grosse with Whulkenhaar (first non-trivial QFT construction in 4D), Abdesselam ("Rigorous quantum field theory functional integrals over the p-adics"), Chaterjee ("A probabilistic mechanism for quark confinement").

For rigorous perturbative QFT, the most-complete thing that I know is Herscovich's book "Renormalization in Quantum Field Theory (after R. Borcherds)" that maybe is even harder than the other nonperturbative works cited here. Also a paper of Viet Dang "Renormalization of Quantum Field Theory on Riemannian manifolds". It uses a lot of REALLY HARD MATHS here.

pd: Sergio Albeverio also works with non-standard analysis, that are pretty cute.





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