Les Houches

People interested: Bryan Zaldivar, José Zurita, Jérémie Quevillon, Jose Miguel No, Nishita Desai, Julia Harz, Daniele Barducci, Dipan Sengupta (dipan@pa.msu.edu), Haiying Cai, Felix Bruemmer, Andreas Goudelis, Gabriel Facini, Sezen Sekmen

Understand the connection between freeze-in models and LLP signatures at the LHC. Is it a generic feature of freeze-in models?

* TODO-list + description + volunteers: todo.pdf

References:

1. Original freeze-in paper: Hall, Jedamzik, John March-Russell, West arXiv
2. LLP signatures: Co, D'Eramo, Hall, Pappadopulo arxiv
3. A concrete realization of the FIMP with LLPs @ LHC, and yielding a standard cosmological history, which turns out to be complementary in DM mass range to the one we have been discussed so far: arxiv arxiv
4. A second realization of non-thermal DM and LLPs (appearing today) https://arxiv.org/pdf/1706.06815.pdf
5. MATHUSLA original paper: Chou, Curtin, Lubatti arxiv
6. MATHUSLA measurements : Curtin, Peskin arxiv
7. BBN constraints: Fradette, Pospelov arxiv

Deliverables:

- A minimal UFO model implementing the idea (YMMV!) External Link → cross section of 0.687 fb for the reference point shown in the FIMP note. For the specific final states: (+,0),(+,-),(-,0),(0,0) = 0.341,0.122,0.113,0.111.

- Mathematica Notebook (or similar) calculating input parameters (TBD).

- Note on “FIMP production via decay” by Bryan boltzmann_fimp.pdf

- Note on the numerical solution and a comparison with the analytical formulae boltzmann_numerical.pdf

- Notes on the classification of signatures for freeze-in according to the quantum numbers of parent particle (and SM decay product) llps_classification.pdf

Triggers (ATLAS): There was some discussion as to what triggers are possible for displaced leptons.

1. This talk from the LLP workshop has some hand drawn plots outlining the trigger possibilities in each region (pg 7-8) https://indico.cern.ch/event/607314/contributions/2542332/attachments/1449594/2234900/LLP_trigger_discussion_group_summary_26april2017.key.pdf It is a bit annoying to read but it is public :p.
2. For muons you can go all the way out to the MS while prompt muon triggers pick decays out to 1 cm with pT~20 GeV (this is for your general consideration, don't quote that in a paper, please)
3. For electrons, there is no explicit d0 cut in the trigger, but I am trying to find out if there are hit level requirements such as requiring a hit on the first tracking layer which might limit the acceptance.