Les Houches

This is an old revision of the document!

---

Project Acronym: BDM

Interested people (during LH): Hua-Sheng Shao, Benjamin Fuks, Andreas Goudelis, Genevieve Belanger, Biplob Bhattacherjee, Dipan Sengupta, Nishita Desai, José Zurita, Jose Miguel No, Jan Heisig, Priscilla Pani, Andre Lessa, Sezen Sekmen, Juhi Dutta

Interest confirmed: [Please add your name here ones you contribute]

Goal : study if it's possible to tag SM hadrons (b's going to B's which in turn decay to J/psi's etc) in dark matter long-lived particle searches, when the mass splitting between the parent particle and dark matter is relatively small (< 35 GeV or so).

Tasks:

1) Generate the SM background (only bb~ ?)

1.a) Through b/b~→J/psi→mu^+mu^-. The price to pay is 2.0*0.0115*0.05961=1.37e-3 (2.0 from b or b~, F(b→J/psi)=1.15% from FF fit, Br(J/psi→mu^+mu^-)=5.961% from PDG).

1.b) Compare efficiency to usual ISR/FSR search (no loss from J/Psi BRs, but larger BG)

1.c) Compare efficiency to R-hadron (HSCP) searches (with a boosted LLP)

2) Decide on a concrete model and delineate the cosmologically interesting parameter space (from conversion-driven freeze-out, freeze-in etc). Candidate model exists, with a sbottom-like parent decaying into a neutralino-like dark matter + a bottom quark.

3) Generate the signal

4) Investigate how to improve S/B (e.g. Br(B→l v)=10%, a third lepton veto, B is displaced in signal but not in background etc).

• Results for the ATLAS DV+MET analysis

List of possible benchmarks

The following parameter points in the “sbottom-neutralino”-simplified model considered in 1705.09292 give you the right relic density via CDFO:

References:

ATLAS Results (J/Psi Background):