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--- micromegas_startpage_freeze-in_andres_tchanelssimplemodels [2021/12/14 20:29]
goudelis
+++ micromegas_startpage_freeze-in_andres_tchanelssimplemodels [2021/12/22 14:49] (current)
goudelis
@@ Line 11: / Line 11: @@
 **Andreas' SM single-generation-no-QCD-zero-temperature CalcHEP implementation**
-{{ :smforuvbehaviournothermal.zip |}}
+{{ :smforuvbehaviournothermal2.zip |}}
 **Andreas' SM single-generation-no-QCD-T-dependent-vev CalcHEP implementation**
-{{ :smforuvbehaviourt-dependentvev.zip |}}
+{{ :smforuvbehaviourt-dependentvev2.zip |}}
+**Andreas' SM single-generation-no-QCD-zero-temperature CalcHEP implementation**
+{{ :SMforUVbehaviourNoThermalNoZ2.zip |}}
+**Andreas' SM single-generation-no-QCD-T-dependent-vev CalcHEP implementation**
+{{ :SMforUVbehaviourNoZ2.zip |}}
@@ Line 72: / Line 78: @@
 //FB let's discuss this later. You also have to be weary about how to calculate with calchep when you are in the Sym. phase//
+//STATUS OF DISCUSSION ABOUT TCUT DEC. 20//
+- We all agree that we cannot do a complete thermal treatment in micromegas and that we are just trying to find a reasonable solution that allows to suppress the behaviour of t-channel diagrams based on the fact that we know that they should be strongly suppressed by thermal masses.
+- I propose to drop the topic of the case where we would have  many t-channel diagrams for the same process. It is clear that the FI module is not as universal as the FO case and since for all models considered so far this situation does not occur no point trying to find a solution for that. In the wiki the list of model included in micromegas is given so anyone can see that for themselves.
+- We still have to decide on what to do in practice, the following solutions are proposed
+A) For processes that have a t-channel contribution, use tcut as defined in relation with the thermal mass. I think we all agree on how to implement tcut as well as how to implement the thermal mass - by default the SM thermal mass. Here what is not clear is how this will affect the s-channel contribution and/or interference. Andreas promised to do some more test on that point so let’s wait for his input.
+B) For processes with only a s-channel contribution, we should not use a cut (I am not sure everyone agrees on this). There are two opinions, a) not to put tcut on processes without t-channel (is there a practical disadvantage in implementing this in micromegas?) b) to treat the s-channel resonance as a decay process which should take care of the cut issue since the decay is not subject to tCut. The added advantage of solution b (which could be implemented irrespective of tcut) is that the calculation is faster. The disadvantage is that there is some uncertainty on how to cut the resonance 3 widths- 5 widths etc… Moreover solution b) from Sasha proposes to use tcut on everything but the decay. This raises some issues as was illustrated in the test I have done with only s-channel. I do not know what to think of this test but I thought  it would  be good  to have a coherent answer to that  as it might explain some issues in the problem  about the interference s and t channel.

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