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MadAnalysis 5 LLP (Long Lived Particle)
LLP with official Delphes 3.4.1
Test with commented example
- Extensive test with signal regions
- Reference event
one sample with unknown particle
LLP with special Delphes package for MA5
Delphes-LLP package is a special improvement of the Delphes package. Associated to MadAnalysis 5 v1.6, it allows the user to perform phenomenological investigations with long-lived particles or to recast existed analysis devoted to this kind of signature.
Current status: the package handles neutral LLPs which decay into leptons in the first layers of the CMS tracker (such as neutralino in the framework of RPV-SUSY). Realistic efficiency is applied to the tracks and D0 parameter is accessible in MadAnalysis 5.
Package[update 2017/08/25]: ma5track_v1.6.tgz
Changes in the Delphes dataformat:
for leptons:
- D0: impact parameter in tranverse plane wrt the closest approach point
- Z: Z-coordinate of the closest approach point
New modules in Delphes:
- MA5EfficiencyD0: applying efficiency to tracks according to the D0 parameter
Efficiency functions is coming from 8-TeV tracking performance of CMS, describing in the following wiki: https://twiki.cern.ch/twiki/bin/view/CMSPublic/DisplacedSusyParametrisationStudyForUser
set EfficiencyFormula { (d0<=20) * (-5.06107e-7 * d0**6 + 0.0000272756 * d0**5 - 0.00049321 * d0**4 + 0.00287189 * d0**3 + 0.00522007 * d0**2 -0.0917957 * d0 + 0.924921) + (d0>20) * (0.00) }
Recast experimental analyses
- CMS EXO-16-022: ongoing
- Center of mass energy: 13 TeV
- Integrated luminosity: 2.6 fb-1
- Summary: A search for new long-lived particles decaying to electrons and muons is presented using data from proton-proton collisions produced in 2015 by the LHC. Events are selected with an electron and muon that both have transverse impact parameter values between 200 μm and 10 cm. Since no significant excess is observed, limits are set on the Displaced Supersymmetry model, with pair production of top squarks decaying into an e-μ final state via R-parity-violating interactions. The results are the most restrictive to date on this model.
- Link to the collaboration page: http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-16-022/
- Link to CDS: https://cds.cern.ch/record/2205146?ln=fr
- Link to Inspire: http://inspirehep.net/record/1479633/
Ongoing development
- Next development: the package will handle charged LLPs which decay into leptons in the first layers of the CMS tracker (such as neutralino in the framework of RPV-SUSY). To reach this goal, the magnetic field of the detector must be applied to the charged LLP before decaying in order to curve the trajectory. This effect will be described by the MA5LLParticlePropagator module.
