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2017:groups:np:llpsm

Recasting and Simplified models for long-lived particles

People interested: Nishita Desai, Stefania Gori, Andreas Goudelis, Sabine Kraml, Andre Lessa, Matthew McCullough, Dipan Sengupta, Benjamin Fuks, Eric Conte, Amit Chakraborty, Abhishek Iyer, Daniele Barducci, José Zurita, Jose Miguel No, Biplob Bhattacherjee, Shankha Banerjee, Haiying Cai, Sezen Sekmen, Gabriel Facini, Andy Buckley, Giovanna Cottin

We now have a mailing list: leshouches-llp-recast AT cern.ch

Topics:

Difficulties of recasting LLP searches

  • See references below.
  • How do detector simulations deal with LLPs?
  • How much error from ignoring the magnetic field for recasting?
  • Track efficiency for reconstructing displaced vertices?
  • Simplified recasting? Efficiencies as a function of (few) relevant kinematical variables
  • How to estimate trigger efficiency for signal different from benchmark (a.k.a. are we throwing away the signal before starting?)

Task List

First task is to implement and validate a few analyses

Search People
Heavy Charged particles Shankha Banerjee, Biplob Bhattacherjee, Abhishek Iyer, Dipan Sengupta
Disappearing tracks José Zurita
Displaced vertices Andre Lessa, Jan Heisig
Displaced leptons / jets Amit Chakraborty, Nishita Desai, Andre Lessa
R-hadrons Jan Heisig (?)

What do we want from this exercise?

  • One document showing validation (or lack of it) for each category
  • A list of models people are interested in re-interpreting these searches for. Is there anything that changes that cannot be smoothly interpolated? e.g. number of tracks? Anything else?

Simplified models definitions

Three main signatures: long-lived charged track (long-lived charged particle), disappearing track or kink track (short-lived charged particle) and displaced vertices (short-lived neutral particle). The long-lived neutral gives standard missing energy signature.

  • MadGraph implementations:
  • Parameterisation of results: mass-vs-mass plane, mass-vs-lifetime, multi-dimensional grids, …
  • Complementarity: Overlap of search strategies as lifetime changes
  • Inclusive simplified models: only the LLP branch topology and decay is relevant?

Efficiencies

  • Computing efficiencies as a function of the LLP kinematics and lifetime
  • Efficiencies for R-hadrons
  • Efficiencies for displaced vertices/kinks
  • Demonstrate usefulness to motivate experimentalists to provide efficiencies

Efficiencies wishlist

  1. Displaced vertices: e, mu eff(d0, pT); jets eff(pT, ctau)
  2. Heavy charged particles: eff(pT, beta, eta)
  3. LL charged particles: eff(pT, beta, eta, ctau)

Q: What is the dependence on isolation? Do we need efficiencies for different isolation criteria?

Triggering

Cross talks

  • Higgs group is interested in exotic decays into LLPs
  • Interplay with LHCb searches

References

  • Simplified Models for Exotic BSM Searches. Jan Heisig, Andre Lessa, Loic Quertenmont, https://arxiv.org/abs/1509.00473
  • Long-Lived Staus and Displaced Leptons at the LHC. Jared A. Evans, Jessie Shelton, https://arxiv.org/abs/1601.01326
  • Prompt Signals and Displaced Vertices in Sparticle Searches for Next-to-Minimal Gauge Mediated Supersymmetric Models. B. C. Allanach, Marcin Badziak, Giovanna Cottin, Nishita Desai, Cyril Hugonie, Robert Ziegler, https://arxiv.org/abs/1606.03099

Current Experimental Analyses

Note: Many ATLAS 13 TeV analyses notes inaccessible without CERN credentials

CMS summary of the searches https://indico.cern.ch/event/550030/contributions/2417789/attachments/1432466/2201005/Antonelli_Aspen2017_CMSLLP.pdf

CMS efficiency parametrisation https://twiki.cern.ch/twiki/bin/view/CMSPublic/DisplacedSusyParametrisationStudyForUser

ATLAS summary of the searches (in progress) https://docs.google.com/document/d/1DqDntN0_2dRLnWwmrMFV30BRkdnKTKYSN33BmQaMbzM/edit?usp=sharing

Experiment Energy Type Analysis
ATLAS 13 TeV DV Search for long-lived, massive particles in events with displaced vertices and missing transverse momentum in 13 TeV pp collisions with the ATLAS detector http://inspirehep.net/record/1589909
ATLAS 13 TeV DV Search for long-lived neutral particles decaying in the hadronic calorimeter of ATLAS at TeV in 3.2/fb of datahttps://cds.cern.ch/record/2219571/files/ATLAS-CONF-2016-103.pdf
ATLAS 13 TeV DV Search for long-lived neutral particles decaying into displaced lepton-jets in proton–proton collisions at 13 TeV with the ATLAS detector http://inspirehep.net/record/1480022/files/ATLAS-CONF-2016-042.pdf
ATLAS 13 TeV DT Search for long-lived charginos based on a disappearing-track signature in p p collisions at 13 TeV with the ATLAS detector https://cds.cern.ch/record/2258131/files/ATLAS-CONF-2017-017.pdf
ATLAS 13 TeV Rhad. Search for metastable heavy charged particles with large ionization energy loss in pp collisions at 13 TeV using the ATLAS experiment https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2016-03/
ATLAS 8 TeV DT Search for charginos nearly mass-degenerate with the lightest neutralino based on a disappearing-track signature in pp collisions at √s = 8 TeV with the ATLAS detector http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2013-01/
ATLAS 8 TeV DV Search for massive, long-lived particles using multitrack displaced vertices or displaced lepton pairs in pp collisions at sqrt(s)=8 TeV with the ATLAS detector https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2014-02/
ATLAS 8 TeV Tracks Search for heavy long-lived multi-charged particles in pp collisions at sqrt(s) = 8 TeV using the ATLAS detector https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2013-20/
ATLAS 8 TeV DV Search for long-lived, weakly-interacting particles that decay to displaced hadronic jets in proton-proton collisions at √s=8 TeV with the ATLAS detector https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2013-12/
ATLAS 8 TeV Disp. jet Search for pair-produced long-lived neutral particles decaying in the ATLAS hadronic calorimeter in pp collisions at √s = 8 TeV https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2012-28/
ATLAS 8 TeV Disp. leptons Search for long-lived neutral particles decaying into lepton jets in proton-proton collisions at √s = 8 TeV with the ATLAS detector https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2013-22/
ATLAS 8 TeV Tracks Searches for heavy long-lived particles with the ATLAS detector in proton-proton collisions at sqrt(s) = 8 TeV https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2013-22/
ATLAS 8 TeV R-had Search for long-lived stopped R-hadrons decaying out-of-time with pp collisions using the ATLAS detector https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2013-03/
CMS 13 TeV Disp. jets Inclusive search for new particles decaying to displaced jets at √s = 13 TeV http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-16-003/index.html
CMS 13 TeV Stopped Search for stopped long-lived particles produced in pp collisions at √s= 13 TeV http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-16-004/index.html
CMS 13 TeV Tracks Searches for Long-lived Charged Particles in Proton-Proton Collisions at √s= 13 TeVhttp://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-15-010/index.html
CMS 13 TeV Disp. leptons Search for displaced leptons in the e-μ channel http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-16-022/index.html
CMS 8 TeV Disp. leptons Search for Displaced SUSY in Dilepton Final States http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/B2G-12-024/index.html
CMS 8 TeV Disp. photons Search for displaced photons using conversions at 8 TeV http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-14-017/index.html
CMS 8 TeV Disp. photon + MET Search for long-lived neutral particles in the final state of delayed photons and missing energy in proton-proton collisions at √s = 8 TeV http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-12-035/index.html
CMS 8 TeV Disp. muons Search for long-lived particles that decay into final states containing two muons, reconstructed using only the CMS muon chambers http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-14-012/index.html
CMS 8 TeV DV Search for long-lived particles decaying to final states that include dileptons http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-12-037/index.html
CMS 8 TeV Stopped Search for decays of stopped long-lived particles produced in proton-proton collisions at √s = 8 TeV http://cms-results.web.cern.ch/cms-results/public-results/publications/EXO-12-036/index.html
CMS 7 & 8 TeV Tracks Searches for Long-lived Charged Particles http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-12-026/index.html
CMS 8 TeV Disp. jets Search for long-lived neutral particles decaying to dijets http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/EXO-12-038/index.html
LHCb 8 TeV Disp. jets Updated search for long-lived particles decaying to jet pairs https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-065.html; see also thesis: http://www.nikhef.nl/pub/services/biblio/theses_pdf/thesis_P_N_David.pdf
LHCb 7 & 8 TeV Search for massive long-lived particles decaying semileptonically in the LHCb detector https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-047.html

Simplified models definitions

Ideas for simplified models and analysis:

  • Displaced tops: SUSY models with stop NLSP, simplified models (emerged from discussion as most interesting candidate model). See here,
  • Disappearing R-hadrons: SUSY models with coloured NLSP and small mass splittings (probably not the most interesting scenario to explore for now).
2017/groups/np/llpsm.txt · Last modified: 2018/01/31 10:33 by giovanna.cottin