The project agenda and todo items

[mmikhasenko]

(Not sure the discussion section is the best place for it)

• Implement the LHCb model
  • Code the Bugg Breit-Wigners for Kpi S wave
  • Set up the input format for the couplings
  • Code the coupling conversion to the DPD convention
• Check implementation
  • Check decay rate fractions for the individual chains
  • Check polarization asymmetries for the individual decay chains (just helicity couplings in the alpha expression)
• Averaged polarization asymmetry vector (an integral with the intensity)
  • Compute it as a numerical convolution with the intensity
  • Use the Lambda subsystem and the alignment chain, compute the average
  • Use the Delta subsystem and compute

[redeboer]

Thanks for adding the data. I'll be writing ComPWA/compwa.github.io#129 into a more general library form in this repo today (and the weekend ;)). That serves a bit like a playground for ComPWA/ampform#277, but the design will remain simplified to describe the Λc decay. Then next week, we can work out the todo items you listed here.

[redeboer]

Not sure the discussion section is the best place for it

I think these (private) discussions pages are perfect for just posting stuff quickly, just like in Slack etc. (The benefit as opposed to issues: support for comment threads.) They can then be converted into issues. And what I like about issues is that they serve as a ticket that can be kept track of, especially with the renewed GitHub project boards. For this project, I collect related issues in this table board.

[redeboer]

Code the Bugg Breit-Wigners for Kpi S wave

Just a thing I was wondering while I was decoding the JSON file: what is the precise formula for the Bugg and the Flatte1450? (Perhaps you already posted, but I don't have access to a good overview atm.)

I assume the Breit-Wigner is the same as in TR-018?

[mmikhasenko]

Yes, the Briet wigner is the same. The BuggBreitWigner is

where

m(Kpi) = sqrt(sigma)
sA = mK^2-mpi^2/2
rho = 2q/m(Kpi)
q # is a breakup

Here is the Julia implementation

The Flatte1405 is also similar to BW, just with

Gamma = Gamma1+Gamma2

where the Gamma1 and Gamma2 are the S-wave energy-dep widths for pK and piSigma.
For the pK channel, q0 is computed using piSigma (senseless made-up stuff).
Here is the Julia implementation

[mmikhasenko]

BuggBW is fixed in #13

[mmikhasenko]

The rates slowly approaching expected values.

That is the current situation

[redeboer]

Rates in the Julia code are not divided by I_tot, no? (Why not?)

[mmikhasenko]

(Sorry, I should read the question twice!)
yes, divided. They are just in %, i.e. multiplied by 100

[redeboer]

Ahh yes of course!

[redeboer]

Rate matrix on its way in #11, just trying to get the matplotlib visualization right :S

[mmikhasenko]

cool! I am trying to identify why you rates are different

[mmikhasenko]

I have done the transformations of the text that we agreed on at the last meeting (Did not read through yet 😆).

Some update on the remaining items:

• some numbers + uncertainties, l.295 @redeboer
• figure 3: left + right @redeboer
• figure 2, + isobar frame (?) @mmikhasenko
• supplemental material .json: 18 models (I0, alpha_i) @redeboer
• a lot of polishing @mmikhasenko, @redeboer, Miriam