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2019 Session

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2019:groups:bsm:bdm

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

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 [UFO model is here + FR file in]

https://phystev.cnrs.fr/wiki/_media/2019:groups:bsm:bdm:sbottom_ufo_model_fr.zip

(from Jan: “MG gives me an error on hypercharge violation, should be checked”). (from Benj: “The error is because mass and gague eigenstates are involved, and no hypercharge can be defined. Just ignore it”).

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).

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:

m_DM[GeV] m_sbot[GeV] \lambda ctau[m]
500 510 2.6e-7 0.22
500 520 2.6e-7 0.05
1000 1010 4.6e-7 0.14
1000 1020 4.8e-7 0.03
1000 1030 9.7e-6 0.003

References:

ATLAS Results (J/Psi Background):

2019/groups/bsm/bdm.txt · Last modified: 2019/07/23 16:00 by jose.zurita