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DISCRETE'08 DISCRETE'08 1 1 M. Mozer (VUB) M. Mozer (VUB) Triggers for New Physics at the LHC M. Mozer IIHE Vrije Universiteit Brussel DISCRETE'08
DISCRETE'08 DISCRETE'08 11M. Mozer (VUB) M. Mozer (VUB)
Triggers for New Physics at the LHC
M. Mozer IIHE Vrije Universiteit Brussel
DISCRETE'08
DISCRETE'08 DISCRETE'08 22M. Mozer (VUB) M. Mozer (VUB)
IntroductionTotal rate: ~109 HzBunch crossing: 40 Mhz
L1 rate: 100 kHz(read out)
HLT rate: 100 Hz(permanent storage)
exotic signals(analysis results)
DISCRETE'08 DISCRETE'08 33M. Mozer (VUB) M. Mozer (VUB)
CMS
trackertracker
Muon systemMuon system
ecalecal
hcalhcal
solenoidsolenoid
MagnetMagnet
TrackerTracker
Hcal
DISCRETE'08 DISCRETE'08 44M. Mozer (VUB) M. Mozer (VUB)
Global Layout
CMSCMS
ControlControlroom,HLTroom,HLT
~100GB/s~100GB/sL1 acceptL1 accept
CERN, Meyrin:mass storage
Surface:HLT processorfarm
Underground:L1-triggerreadout
HLTHLT
L1L1
CERNCERNstoragestorage
detector
digitizers
Front endpipeline
40MHz
100kHz (1/400)
100kHz
100Hz (1/1000)
Readoutbuffers
Processorfarm
distributor
Only two trigger levels● L1: custom electronics/FPGAs● HLT: large PC cluster
DISCRETE'08 DISCRETE'08 55M. Mozer (VUB) M. Mozer (VUB)
L1 Overview
DISCRETE'08 DISCRETE'08 66M. Mozer (VUB) M. Mozer (VUB)
L1 Data Flow
CSCRPChcalecalHF DT
Towers Seg-ments
Seg-ments
track track
Global trig.
Local calo trig
Global calo trig
Towers Towers
Patternmatch
Detectorcalo muon
isolation
e/ cands.jets 4 each
Global Trigger
4 2x4e/, 8 jet, 4 ET, ETmiss ...
No centraltracker at L1
only muon system
DISCRETE'08 DISCRETE'08 77M. Mozer (VUB) M. Mozer (VUB)
HLT Overview
● Trigger Path: sequence of reconstruction, filters, prescales
● Ordered for best timing performance(do slowest reconstruction step last)
● All paths run for all events● Set of all Paths = Menu● Use local reconstruction only
No L1 seed, not usedin HLT
L1 seeds
Area around L1 seedsused in HLT
DISCRETE'08 DISCRETE'08 88M. Mozer (VUB) M. Mozer (VUB)
New Physics, Old Signatures
Standard Model New Physics
Inclusive calibrationET, ET,miss ... background
detector studies
Single Objects EW, QCD, high mass SUSY(electrons, muons, Drell-Yan Z', W'jets, ...) Graviton
leptoquarks...
Combinations W, top,... low mass SUSY(di-electron,electron+jet,muon+ET,miss ...)
tight isolation/high thresholdsefficiencies well known
loose isolation/low thresholdsefficiencies difficult
DISCRETE'08 DISCRETE'08 99M. Mozer (VUB) M. Mozer (VUB)
New Physics, Old Signatures
Standard Model New Physics
Inclusive calibrationET, ET,miss ... background
detector studies
Single Objects EW, QCD, various SUSY(electrons, muons, Drell-Yan Z', W'jets, ...) Graviton
leptoquarks...
Combinations W, top,... various SUSY(di-electron,electron+jet,muon+ET,miss ...)
DISCRETE'08 DISCRETE'08 1010M. Mozer (VUB) M. Mozer (VUB)
New Physics, New Signatures
SM-like signatures well covered, but exotics may fail to trigger:
Lifetime
Mass
Well covered
May sufferfrom background
Tracking difficultfor large vertex displacement
Slow velocity problematic for detector synchronisation
Difficult to distinguishfrom SM particles
DISCRETE'08 DISCRETE'08 1111M. Mozer (VUB) M. Mozer (VUB)
Example
Heavy, metastable, charged particles (i.e. R-hadrons in split SUSY)=> produced in collision=> loose energy from ionisation=> may be stopped in the detector material=> decay at a later time (minutes...hours)
Signature: Jets originating from dense detector parts while beam is off
Solution: run Calo triggerduring beam off periods
Running sinceSeptember to gather background data
DISCRETE'08 DISCRETE'08 1212M. Mozer (VUB) M. Mozer (VUB)
Trigger in Practice
Most of the HLT Most of the HLT functionalities testedfunctionalities tested
Global Run Global Run July 08July 08
● Online reconstruction(CPU performance, memory footprint)
● High rate tests (random triggerup to ~80kHz)
● L1 seed to HLT● Streaming calibration data (reduced event content) parallelto full events
● Complete chain of data transfer up to Tier0 at CERN
DISCRETE'08 DISCRETE'08 1313M. Mozer (VUB) M. Mozer (VUB)
• Routinely running High-Level-Trigger menu (+ dedicated cosmic muon trigger path)
• Global fit with “L3” tracker track, seeded from “L2” muon track, seeded from “L1” trigger candidate:
Run 58733, event Run 58733, event
17411351741135
DISCRETE'08 DISCRETE'08 1414M. Mozer (VUB) M. Mozer (VUB)
Summary
Technical status:● CMS trigger hardware/software ready for data● Successfully running with cosmic muons● Performs as expected
New Physics Prospects:● SM like signatures (leptons, jets, ...)well covered
● Many exotic signatures covered
To Do:● Take data● Find Signal
