Triggers for B physics Julie Kirk RAL Overview

Triggers for B physics Julie Kirk RAL • Overview of B trigger strategy • Algorithms – current status and plans • Menus • Efficiencies from data • Summary ATLAS UK physics meeting, 10/01/08 1

B physics at LHC • LHC: proton-proton collisions at √s = 14 Te. V bunch crossing rate 40 k. Hz • High bb production cross section: ~500 µb (~ 1 in 100 p-p collisions → bb pair). Must select those of interest. • B-physics programme includes: – CP violation (e. g. B→J/ψ(X), B→ ) – Bs oscillations (e. g. Bs→Dsπ, Bs→Dsa 1) – Rare decays (e. g. B→ (X), B→K*γ) – J/ψ→μμ useful for detector alignment • B-trigger is based on single and di-muons: – BR ~ 10 % – but clean signature at early level in trigger – gives flavour tag (needed in many analyses) ATLAS UK physics meeting, 10/01/08 2

Overview of B-trigger strategy • High luminosity (>2 x 1033 cm-2 s-1) use di-muon trigger (p. T > 6 Ge. V) – B → J/ψ( ) X – Rare decays with di-muon , e. g. B→ , B→K 0* • Low luminosity (<2 x 1033 cm-2 s-1) add a single muon trigger with additional JET/EM ROI information from LVL 1. At LVL 2 have 2 possible approaches: – Full reconstruction (Full. Scan) inside inner detector (time costly) – Use LVL 1 Regions of Interest (Ro. I) to seed LVL 2 reconstruction: • Jet Ro. I for hadronic final states (e. g. Bs→Ds( π)π) • EM Ro. I for e/g final states (e. g. J/ψ→ee, K*γ, γ) • Muon Ro. I to recover di-muon final-states in which second muon was missed at LVL 1. Allows us to have a broad programme of B-physics in initial low luminosity period. Continue with rare-decay searches at high luminosity ATLAS UK physics meeting, 10/01/08 3

Muon B trigger: Topological di-muon (Jpsimumu, Bmumu, Upsimumu, Bmumu. X) Seeded by two L 2_mu. X HLT muon confirmation L 1_MUX Fast Id. Scan_muon • HLT algos combine pairs of tracks make mass and vertex cuts Signatures: • Comb L 2_mu. X EF tracking Trig. Moore EF Missing part EF_mu. X ATLAS UK physics meeting, 10/01/08 X = 4 Ge. V or 6 Ge. V EF_mu. X Use same algo configured with different mass cuts: EF_mu. X EFBmumu. Fex EFBmumu. Hypo 2 MUX_Bmumu, 2 MUX_Jpsimumu, 2 MUX_Upsimumu Bmumu: 500 -8000 Me. V Jpsimumu: 2600 -3400 Me. V Upsimumu: 8500 -10500 Me. V • 2 MUX_Bmumu. X – Being implemented 2 MUX_Bmumu In early running also have 2 mu. X with no further processing – for Drell Yan and cross-checks 4 4

Muon B trigger: Trig. Di. Muon (Jpsimumu, Bmumu, Upsimumu, Bmumu. X) L 1_MUX Id. Scan / Si. Track L 2_mu. X Seeded by single L 1_MUX/L 2_mu. X, search for second in large Ro. I around the first Trig. Di. Muon Signatures: L 2 Di. Mu. Hypo L 2_MUX_Jpsimumu EF tracking Trig. Mu. Girl L 2_mu. X_Jpsimumu EF Missing part MUX_Bmumu, mu. X_Jpsimumu, MUX_Upsimumu_FS, etc. These again use same code with different mass cuts MUX_Bmumu. X - being implemented EFDi. Mu. Hypo MUX_Jpsimumu mu. X_Jpsimumu ATLAS UK physics meeting, 10/01/08 5 5

Di-muon B triggers Examples of efficiencies for different triggers (few 100 s events) Trigger J/y→m 6 m 3 2 MU 6_Jpsimumu 15% 2 MU 4_Jpsimumu 38% MU 6_Jpsimumu 73% MU 6_Jpsimumu_FS 73% →m 4 m 4 Requiring only 1 LVL 1 muon and using Trig. Di. Muon to find the second muon with lower p. T thrshold greatly increases efficiency. 2 MU 4_Upsimumu 36% MU 4_Upsimumu 0. 6% MU 4_Upsimumu_FS 67% ATLAS UK physics meeting, 10/01/08 For Upsimumu muons are well separated and we need Full. Scan 6

Hadronic B decays L 1_MUX_J 5 Bs Ds ( φ ( K+ K- ) π Confirm muon at L 2 Seeded by single L 1_MUX_J 5, search for hadronic decay in Ro. I around J 5 or Full. Scan Id. Scan / Si. Track_Bphysics / Full. Scan Combine tracks make mass cuts to find and Ds Signatures: MUX_Ds. Phi. Pi, MUX_Ds. Phi. Pi_FS, mu. X_Ds. Phi. Pi, etc. Implemented at L 2 and EF ! Needs work to reduce rate at higher luminosities, particularly at EF – use vertexing, reconstruct the B? L 2 Ds. Phi. Pi. Fex L 2 Ds. Phipi. Hypo L 2_MU(mu)X_Ds. Phi. Pi(_FS) EF Confirm muon at EF EF tracking (B physics / Full. Scan) EFDs. Phi. Pi. Fex EFDs. Phipi. Hypo MU(mu)X_Ds. Phi. Pi(_FS) ATLAS UK physics meeting, 10/01/08 7 7

Hadronic B decays Efficiency Ro. I vs Full. Scan Timing tests during November technical run Ro. I Full. Scan • Ro. I vs Full. Scan track reconstruction times • Athena. MT (solid) vs L 2 PU (shaded) to study effects of real data access time (+~50%). ATLAS UK physics meeting, 10/01/08 8

EM B decay J/y→ee, B → K*g, B → g Seeded by single L 1_MUX_EM 3: Search for EM decay in Ro. I around EM 3 or Full. Scan L 1_MUX_EM 3 Confirm muon at L 2 Id. Scan / Si. Track_Bphysics L 2 Jpsiee. Fex L 2 Jpsiee. Hypo Signatures: MUX_Jpsie 5 e 3 mu. X_Jpsie 5 e 3_FS mu. X_Bgamma 5 x, etc. • Jpsiee currently implemented at L 2 • For Bgamma 5 x: there is a chain setup with dummy hypo to allow us to perform feasibility studies. ATLAS UK physics meeting, 10/01/08 L 2_MU(mu)X_Jpsie 5 e 3 Confirm muon at EF EF EF tracking (B physics) Missing EFJpsiee. Fex part EFJpsiee. Hypo MU(mu)X_Jpsie 5 e 3 9 9

B → Kg, B → g L 1: L 2: “standard” low ET photon cuts from Egamma group then reconstruct /K* gives: 70% efficiency for background ~6% of L 2_muon rate (~6 -25 Hz) Add “extra “ calo cuts (cluster width, etc. ) gives 60% efficiency background 10 Hz. Need to optimize the cuts and implement at EF ATLAS UK physics meeting, 10/01/08 10

Menus for different luminosity scenarios • Choose muon threshold use of Ro. I/Fullscan track reconstruction to optimize performance at different luminosities • 1031 : Use L 1_MU 4 plus tracks reconstructed by ID Fullscan. At startup have 2 muon trigger with no further selection for Drell Yan. • 1032: Use L 2_mu 4 before HLT slections and use track reconstruction in Muon, Jet and EM Ro. I, rather than Full. Scan • • 1033: Raise muon threshold to mu 6 ATLAS UK physics meeting, 10/01/08 11

Extracting efficiencies from data • • Don’t want to rely on MC for our trigger efficiencies Look at using data: J/y→μμ used with “tag and probe” method to get single and then di- muon efficiencies (see CSC note). • Work just starting need to look at other channels. 1 ENDCAP BARREL 2 seed muon (MU 06) probe muon J/Y (2. 88 Ge. V<M <3. 3 Ge. V) ATLAS UK physics meeting, 10/01/08 3 Trigger eff. curve for Pt n. Endcap n. Barrel – Fitting result 12

Summary • • Much recent work to implement new trigger chains and menus. Still much to do – – • EF implementation in most chains Tuning cuts (efficiency versus rate) Efficiency studies – how to get efficiencies from data? Monitoring – setting up histograms and automatic checking Anybody interested in getting involved please let us know. ATLAS UK physics meeting, 10/01/08 13

Backup slides ATLAS UK physics meeting, 10/01/08 14

Menus: Status in 13. 0. 3 Signatures in 13. 0. 3 (default menu): ["MU 6_Ds. Phi. Pi", "MU 4_Ds. Phi. Pi", "mu 6_Ds. Phi. Pi", "mu 4_Ds. Phi. Pi", "MU 6_Ds. Phi. Pi_FS", "MU 4_Ds. Phi. Pi_FS", "mu 6_Ds. Phi. Pi_FS", "mu 4_Ds. Phi. Pi_FS", "MU 4_Jpsie 5 e 3_FS", "MU 4_Jpsimumu", "MU 6_Jpsimumu", "MU 4_Upsimumu", "MU 6_Upsimumu", "MU 4_Bmumu", "MU 6_Bmumu", "mu 4_Jpsimumu", "mu 6_Jpsimumu", "mu 4_Upsimumu", "mu 6_Upsimumu", "mu 4_Bmumu", "mu 6_Bmumu", "2 MU 4_Bmu 4", "2 MU 6_Bmu 6", "2 MU 4_Bmu 4 x", "2 MU 6_Bmu 6 x", "2 MU 4_Jpsimumu", "2 MU 6_Jpsimumu", "2 MU 4_Upsimumu", "2 MU 6_Upsimumu"]. ATLAS UK physics meeting, 10/01/08 15

1031 (Lumi 1 E 31. py) LVL 1 only: L 1_2 MU 4 HLT passthru’ : 20 Hz L 1_MU 4 prescale ~200 HLT pass thru’ : 5 Hz Aim: HLT triggers based on Full. Scan for all events with LVL 1 MU 4 LVL 1 + Muon at HLT 2 mu 4 : ~10 Hz mu 4 prescale ~100 : 5 Hz Still need to implement Trig. Di. Muon triggers to use Full. Scan LVL 1 + ID & MU at HLT: MU 4_Ds. Phi. Pi_FS, MU 4_Jpsimumu, MU 4_Upsimumu, MU 4_Bmumu, 2 MU 4_Bmu 4, 2 MU 4_Jpsimumu, 2 MU 4_Upsimumu Note: Full-scan run at rate of either: • L 1_MU 4 : 1 k. Hz * 80 ms = 80 cores = 2% LVL 2 farm UK physics meeting, 10/01/08 • ATLAS L 2_mu 4 : ~400 Hz => <1% LVL 2 farm Loose selections ~10 Hz 16

1032 (Lumi 1 E 32. py) LVL 1 only: L 1_2 MU 4 HLT pre-scale ~100 : 2 Hz L 1_MU 4 prescale ~5000 HLT pass thru’ : 2 Hz LVL 1 + Muon at HLT 2 mu 4 pre-scale ~20 : ~5 Hz mu 4 prescale ~2000 : 2 Hz Increased prescales to achieve ~2 Hz LVL 1 + ID & MU at HLT: mu 4_Ds. Phi. Pi, mu 4_Jpsimumu, mu 4_Upsimumu, mu 4_Bmumu, 2 MU 4_Bmu 4, 2 MU 4_Jpsimumu, 2 MU 4_Upsimumu Require L 2 mu 4 and use HLT reconstuction in Ro. I Note: Could run Full-scan run at: • L 2_mu 6 : 1 k. Hz * 80 ms = 80 cores = 2% LVL 2 farm ATLAS UK physics meeting, 10/01/08 Tighter selection cuts needed to achieve ~10 Hz 17

1033 (not implemented yet) LVL 1 only: L 1_2 MU 6 HLT pre-scale ~100: 2 Hz L 1_MU 6 prescale ~10000 HLT pass thru’ : 2 Hz Raise muon threshold to mu 6 LVL 1 + Muon at HLT 2 mu 6 pre-scale ~50 : ~2 Hz mu 4 prescale ~2000 : 2 Hz LVL 1 + ID & MU at HLT: mu 6_Ds. Phi. Pi, mu 6_Jpsimumu, mu 6_Upsimumu, mu 6_Bmumu 2 MU 6_Bmu 6, 2 MU 6_Jpsimumu, 2 MU 6_Upsimumu ATLAS UK physics meeting, 10/01/08 Additional cuts needed to achieve ~10 Hz (probably need decay length cuts) 18