Les Houches

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 freeze-in with much-stronger-than-feeble couplings and test the corresponding scenarios at the LHC (and direct/indirect detection experiments).

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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 large-ish couplings, the mediator is not produced on-shell 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 t-channel 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 freeze-in 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 LHC-accessible masses).

3) Compute direct detection constraints. The t-channel model, in particular, has a loop-induced contribution which must be calculated

4) Consider “peripheral” constraints, such as flavour constraints in the t-channel 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 t-channel model considered in https://arxiv.org/abs/1811.05478: https://feynrules.irmp.ucl.ac.be/wiki/FICPLHC

References: