add Lb2pKg model

[IlyaSegal]

Adds Lb2pKg with json and qmd files,

Closes #6

[redeboer]

Super nice!
Seems that the model results in NaN values for now (?)

[redeboer]

@IlyaSegal can you add *.html to .gitignore and remove this file?
Afaics, these files are generated in the source code folder (instead of _build/html) if you use quarto render (=pixi run doc).

[mmikhasenko]

I found the cause of the Inf: it was the normalization factors from #31

The BlattWeisskopf is currently defined as zˆL / pol(z) where z = R*p. If the radius is 0, the factor is 0. And 1/0 gives Inf resulting in NaN.

Now, the formfactors are replaced by the newly introduced MomentumPower factors.

[mmikhasenko]

The page should be built. The Dalitz looks reasonable, but the tests are not passed.

[redeboer]

Beautiful!

[mmikhasenko]

Shall we aim to merge it today?

AFAIR, the status is that the validation tests fail.
A suggestion to proceeded is to create more validations.

Here is an input from the "true" model implementation, what we need to proceed here (open Lb2pKpi notebook, evaluate, report number here):

• all lineshapes evaluated at sigma1, or sigma2, or sigma3
• for a given kinematic point (say validation1), evaluate all chains separately: inpolarized_intensity(model[3:3], sigma_test1)

How does it sound @IlyaSegal

[IlyaSegal]

After updating couplings, all validation points are yellow (difference in the third decimal digit).
Almost congratulations @mmikhasenko

[mmikhasenko]

That was it, congratulations!

[redeboer]

Nice, preview looks good now!