Trigger Strategies for Long-Lived Particles LHC Searches for LL BSM Particles: Theory Meets Experiment UMass - 12-14 Nov 2015 Andrea Coccaro University of Geneva Andrea Coccaro 1 14 November, 2015 - Trigger Strategies for LLP
Introduction Need to be smart in building the triggers and in picking up the right triggers 1. dedicated vs standard 2. inclusive vs exclusive 3. threshold vs multiplicity 4. signal vs control regions 5. ... The trigger-building primer ◮ function of mass, decay products, boost, lifetime ◮ rough information at L1, no tracks ◮ limited readout and limited reconstruction at HLT ◮ early rejection principle ◮ driven by rate reduction, then by signal efficiency Trigger strategies are evolving fast, but targets are moving as well! Andrea Coccaro 2 14 November, 2015 - Trigger Strategies for LLP
Outline 1. LLP triggers in calorimeter and muon spectrometer 2. LLP triggers in the tracker 3. other dedicated triggers 4. simplified menu evolution 5. exotic approaches (?) Andrea Coccaro 3 14 November, 2015 - Trigger Strategies for LLP
Calorimeter Ratio Trigger Ingredients: ◮ TAU40 at L1 ◮ track and jet reconstruction at the HLT ◮ no tracks with p T > 1 GeV in ∆ R < 0 . 2 around the jet axis ◮ log( E HAD / E EM ) > 1 . 2 ◮ beam halo removal using calorimeter cell timing 0.4 jet Energy [a. u.] 〉 ) η ATLAS Simulation EM ATLAS Simulation m =140 GeV, m =20 GeV - 2 π 7 H 0.3 10 /E m =140 GeV, m =20 GeV m =126 GeV, m V =10 GeV cell π π H H V HAD V η m =100 GeV, m =25 GeV π 6 H 0.2 10 1.5 V (E 10 5 0.1 10 log 1 〈 4 0 10 0.5 3 -0.1 10 0 2 -0.2 10 -0.5 -0.3 10 -0.4 1 -1 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0 0.5 1 1.5 2 2.5 3 3.5 4 φ φ - r [m] cell jet Key feature: Isolated jet with very low EM fraction Andrea Coccaro 4 14 November, 2015 - Trigger Strategies for LLP
Muon RoI Cluster Trigger Ingredients: ◮ 2MU10 at L1 ◮ muon cluster asking for 3 (4) muon RoIs in ∆ R < 0 . 4 in the barrel (end-cap) MS ◮ no tracks with p T > 5 GeV in ∆ R < 0 . 4 around the muon cluster direction ◮ no jets with E T > 30 GeV in ∆ R < 0 . 7 around the muon cluster direction 5 Average number of RoIs Average number of RoIs ATLAS Simulation 7 ATLAS Simulation m =140 GeV, m =20 GeV m =140 GeV, m =20 GeV 4.5 H π H π V V m =126 GeV, m =10 GeV m =126 GeV, m =10 GeV H π H π V V 4 m =100 GeV, m =25 GeV 6 m =100 GeV, m =25 GeV H π H π V V 3.5 5 3 4 2.5 2 3 1.5 2 1 1 0.5 0 0 0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 10 12 14 r [m] |z| [m] Key feature: Isolated cluster of muon region of interests Andrea Coccaro 5 14 November, 2015 - Trigger Strategies for LLP
Timing window acceptance Jet energy within 1% for time shifts up to 12 ns - reference ◮ ≥ 93% of the π v decays arrive in the HCal with a ∆ t < 10 ns Muon trigger accurately matches events for ∆ t < 6 ns - reference ◮ ≥ 75% of the π v decays arrive in the MS with a ∆ t < 6 ns 1.1 1.05 t < 10 ns t < 6 ns ATLAS Simulation ATLAS Simulation 1 1.05 0.95 ∆ 1 ∆ decays with decays with 0.9 0.95 0.85 0.9 0.8 0.85 v m =140 GeV, m =20 GeV m =140 GeV, m =20 GeV π 0.75 v H π H π π V Fraction of V m =126 GeV, m =10 GeV m =126 GeV, m =10 GeV Fraction of H π H π 0.8 V V m =100 GeV, m =25 GeV 0.7 m =100 GeV, m =25 GeV H π H π V V 0.75 0.65 0.7 0.6 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 π π mean proper lifetime [m] mean proper lifetime [m] v v Andrea Coccaro 6 14 November, 2015 - Trigger Strategies for LLP
Trigger Efficiency (with respect to truth) 0.7 Trigger Efficiency Trigger Efficiency ATLAS Simulation ATLAS Simulation 0.25 m =140 GeV, m =20 GeV π H V 0.6 m =126 GeV, m =10 GeV π H V m =100 GeV, m =25 GeV π H 0.2 V 0.5 m =140 GeV, m =20 GeV π H V m =126 GeV, m =10 GeV π H 0.4 0.15 V m =100 GeV, m =25 GeV π H V 0.3 0.1 0.2 0.05 0.1 0 0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 r [m] r [m] Andrea Coccaro 7 14 November, 2015 - Trigger Strategies for LLP
LLP triggers in action Triggers for displaced decays of long-lived neutral particles [JINST 8 (2013) P07015] Standalone vertex finding in the ATLAS muon spectrometer [JINST 9 (2014) P02001] Search for a light Higgs boson decaying to LL particles [PRL 108 (2012) 251801] Search for long-lived neutral particles decaying into lepton jets [JHEP 11 (2014) 088] Search for pair-produced LL neutral particles decaying in the HCal [PLB 743 (2015) 15-34] Search for LL particles that decay to displaced hadronic jets [Phys. Rev. D 92, 012010 (2015)] 2 10 -2 BR [pb] 10 SM a µ σ HADES KLOE -1 ,5 ATLAS ATLAS σ s = 8 TeV, 19.5 fb m =110 GeV BaBar ~ a favoured A1 1 g 10 -3 µ , ± 2 σ BR / -1 m =250 GeV s = 8 TeV, 19.5 fb E774 m = 125 GeV ~ a APEX ∈ e H g Kinetic mixing parameter m =500 GeV -4 E141 90% CL ~ 10 m =10 GeV π × g 10 BR 40% × V m =800 GeV Orsay m =25 GeV σ ~ BR 20% π g BR 10% σ 95% CL Upper Limit on -5 V 10 m =40 GeV m =1200 GeV U70 BR 5% 95% CL Upper Limit on π ~ g ATLAS V BR 15% -6 − 10 1 10 1 -7 10 CHARM E137 BR 5% LSND 10 -8 − 1 SN 10 -9 10 − 2 10 BR 1% -10 ATLAS 10 -1 20.3 fb s = 8 TeV − 10 -11 2 10 -3 -2 -1 − − 10 10 10 1 1 2 1 2 10 1 10 10 10 1 10 10 m [GeV] π τ τ γ proper lifetime ( ) [m] Singlino proper lifetime ( ) [m] c c d v Andrea Coccaro 8 14 November, 2015 - Trigger Strategies for LLP
Outline 1. LLP triggers in calorimeter and muon spectrometer 2. LLP triggers in the tracker 3. other dedicated triggers 4. simplified menu evolution 5. exotic approaches (?) Andrea Coccaro 9 14 November, 2015 - Trigger Strategies for LLP
Trackless Jet Trigger Ingredients: ◮ MU10 and J20 at L1 ◮ track, jet and muon reconstruction at the HLT ◮ confirmation of muon and jet at L1 within ∆ R < 0 . 4 ◮ no tracks with p T > 0 . 8 GeV in ∆ R < 0 . 2 around the jet axis 0.06 decays Trigger Efficiency ATLAS Simulation ATLAS Simulation 0.5 0.05 v π Fraction of 0.4 m =140 GeV, m =20 GeV 0.04 m =140 GeV, m =20 GeV π H π H V V m =126 GeV, m =10 GeV m =126 GeV, m =10 GeV π H π H V m =100 GeV, m V =25 GeV m =100 GeV, m =25 GeV π H π H 0.3 0.03 V V 0.2 0.02 0.1 0.01 0 0 0 2 4 6 8 10 0 1 2 3 4 5 6 7 8 9 10 r [m] Number of L2 tracks Key feature: Jet (and muon) with track isolation Andrea Coccaro 10 14 November, 2015 - Trigger Strategies for LLP
Expected Fraction of Events decays ATLAS Simulation Trackless Jet trigger 0.12 m =140 GeV, m =20 GeV π Calorimeter Ratio trigger H V v π Muon RoI Cluster trigger 0.1 Fraction of triggered 0.08 0.06 0.04 0.02 0 -1 10 1 10 π mean proper lifetime [m] v Nice complementarity among the three triggers Andrea Coccaro 11 14 November, 2015 - Trigger Strategies for LLP
Trigger Rates and Pile-Up Dependence 2 1.2 Rate [Hz] Ratio of trigger rates ATLAS ATLAS Simulation 1.8 〈 µ 〉 s = 8 TeV, peak 26.6 1 1.6 Trackless Jet trigger 1.4 Calorimeter Ratio trigger 0.8 1.2 Muon RoI Cluster trigger 1 0.6 0.8 0.6 p >3 GeV / p >5 GeV 0.4 T T p >1 GeV / p >5 GeV 0.4 T T 0.2 0.2 0 0 5 10 15 20 25 30 35 40 2 2.5 3 3.5 4 4.5 5 5.5 〈 µ 〉 33 -2 -1 Inst. Luminosity [10 cm s ] The track-isolation requirement on the Muon RoI Cluster trigger ( p T > 5 GeV) is not pile-up dependent while requiring track isolation for tracks with p T > 1 GeV makes the trigger response pile-up dependent. Andrea Coccaro 12 14 November, 2015 - Trigger Strategies for LLP
25 reconstructed events in ∼ 5 cm in a Z → µµ candidate event (2012 data) Andrea Coccaro 13 14 November, 2015 - Trigger Strategies for LLP
CMS Displaced Jet Trigger Targeting decays within the tracking volume ◮ H T > 300 GeV using all jets with E T > 40 GeV and | η | < 3 ◮ at least 2 jets with E T > 60 GeV with no more than ◮ 2 tracks with 3D impact parameter < 300 µ m ◮ 15% of the jet total energy associated to tracks with 3D impact parameter < 500 µ m Non sensitive to the Higgs at 125 GeV but greatly sensitive to short lifetimes -1 -1 18.5 fb (8 TeV) 18.5 fb (8 TeV) 10 2 BR [pb] 10 CMS CMS -1 ATLAS s = 8 TeV, 19.5 fb ) [pb] 95% CL limits: 95% CL limits: ) [pb] 1 m = 200 GeV m = 400 GeV m =300 GeV, m =50 GeV × Φ H m = 50 GeV H 10 π V m = 50 GeV X m =600 GeV, m =50 GeV σ X Φ π q m = 150 GeV 95% CL Upper Limit on q X m =600 GeV, m V =150 GeV q q Φ Exp. limits ( ± 1 σ ) π → Exp. limits ( ± 1 σ ) V → m =900 GeV, m =50 GeV Φ π -1 V (X 1 10 m =900 GeV, m =150 GeV (X Φ π 1 2 V B 2 B × × XX) XX) -2 10 → − 1 → 10 (H (H σ -1 σ 10 -3 10 − 2 10 10 − 1 10 2 1 10 2 1 10 1 10 10 π proper lifetime ( c τ ) [m] X c [cm] X c [cm] v τ τ Andrea Coccaro 14 14 November, 2015 - Trigger Strategies for LLP
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