Precision Calculations

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Sorry Andreas 
 The talk dragged on and I left didn't know it was a 2h special talk. 

Cédric's et al  paper: Sasha may have used MO with v(T) as a trick, but I am not sure, or only to keep (somehow) GI. Using v(T) would always give m_gamma=m_gluon=0. Moreover v(T) would have a very specific T dependence, unlike thermal masses. In the paper it is very clear that the masses are **thermal** (Debye) masses (and sure neglecting diff. between Long/transv modes). These can be written in all generality once we specify what is in the bath, and that is easy, in freeze-in MO requires to list what is in the bath (apart from DS and non DS/SM).

The more amazing thing, Fig~2 (although this is, I think,  calculating processus entering  equilibrium, but the same calculation applies for scattering/production). So Fig~2 shows the ratio of the contribution/cross sections with and without masses (thermal) implemented. The caption reads : These effects of thermal masses are illustrated in Fig. 2 which shows the ratio of
the reaction rates in Eq. 15, calculated with and without
thermal masses.------> Footnote[5]" and the footnote reads
Footnote[5]
In the absence of thermal masses, **we regulate the forward singularity of t-channel diagrams by cutting off phase space regions where the transferred momentum is less than ΛQCD* So the cut when no masses is cut because we reach the confining regime, so the cut is something. But all this goes to show that the recipe was known 

The same can be done for spin-1, but its more tricky than just v(T) but then the asymptotic cross section is a simple general analytical formulae. but this I have written about ad nauseam

Sorry I did not want to write this email

Best
F
ps: I have added my name next to Cedric for the EWPT in the table of projects. Adding him in this discussion at this moment may be counterproductive....... This should not be interpreted that I am against him joining this or any other project





----- Original Message -----
From: "Genevieve BELANGER" <belanger@lapth.cnrs.fr>
To: "Andreas Goudelis" <andreas.goudelis@clermont.in2p3.fr>, "Fawzi BOUDJEMA" <fawzi.boudjema@lapth.cnrs.fr>, "micro.omegas" <micromegas@lapth.cnrs.fr>
Sent: Friday, 3 December, 2021 15:31:27
Subject: Re: Progress / cut thermal mass

Dear Fawzi,

     This paper deals with a specific model, we could include thermal 
mass because there were no chiral couplings. The same method cannot be 
used in general. Moreover calculations were not done in micromegas, they
were done by Cedric in mathematica, many steps were checked by Sasha 
with micromegas (I think he included thermal mass through v(T)). We took
TR=100GeV not to have to deal with SB.

It seems that we could in this model compare the result with thermal 
mass with the one with ptcut.

Cedric was also working on FI in singlet scalar with/without symmetry 
breaking - his results were similar to those presented by Torsten. 
Although he is not interested in micromegas maybe we should add Cedric 
to the discussion since he is doing calculations of relic with thermal 
mass and SB effects.

Best

Genevieve
Precision Calculations

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