Les Houches

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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 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 arXiv:

Tasks:

1) Of all the possible models that one can consider,

2) Depending on the findings of 1) we'll see how to proceed.

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 .

References: