Les Houches
2019 Session
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Project Acronym: FISLHC
Interested people: Andreas Goudelis, Genevieve Belanger, Dipan Sengupta, Nishita Desai, Aoife Bharucha, José Zurita, Jose Miguel No, Jan Heisig, Andre Lessa, Sezen Sekmen, Adil Jueid, Giacomo Polesello.
[Please add (or remove!) your name and feel free to edit tasks!]
Goal (generalised following discussion on 26/6/2019) : study if it's possible to realise freezein with muchstrongerthanfeeble couplings and test the corresponding scenarios at the LHC (and direct/indirect detection experiments).
The answer appears to be positive according to our  preliminary  findings and estimates, and the trick is to assume a low reheating temperature. We discussed two effects (corresponding to regimes which can also overlap):
* The reheating temperature being below the dark matter mass. In this case, in order to get the relic right one needs to increase the DM couplings since DM production relies on the tails of the distributions of the thermal bath particles.
* The reheating temperature being below the mediator mass. In this case, even for largeish couplings, the mediator is not produced onshell and the effective interaction can be feeble.
Of all models that one can think of, we agreed to consider three simple scenarios: * The singlet scalar model * A 2HDM + pseudoscalar singlet model * A tchannel model, like the ones in https://arxiv.org/abs/1811.05478 or https://arxiv.org/abs/1705.09292
Tasks:
1) Write model files for all models
2) Compute the freezein DM abundance by varying the model parameters and the reheating temperature. For the latter, an indicative interval could be between 1 GeV (such that we're roughly above the QCD scale) and 1 TeV (such that we don't go far above LHCaccessible masses).
3) Compute direct detection constraints. The tchannel model, in particular, has a loopinduced contribution which must be calculated
4) Consider “peripheral” constraints, such as flavour constraints in the tchannel model
5) Compute LHC constraints (presumably quite a few channels, depending on the model)
UFO files for different benchmark models:
2HDM + pseudoscalar $a$ 2HDM+a UFO file (by Uli Haisch) from 1810.09420 (LHC DM Working Group).
Feynrules file (with some restrictions w.r.t. Uli's) for 2HDM + pseudoscalar $a$ 2HDM+a .fr file .
Feynrules files for the tchannel model considered in https://arxiv.org/abs/1811.05478: https://feynrules.irmp.ucl.ac.be/wiki/FICPLHC
References: