Trigger & Analysis

1. Trigger & Analysis Avi Yagil UCSD

2. Introduction Rates & cross sections Beam Crossings What do we trigger on? Trigger Table (example) Trigger terminology Trigger paths Prerequisites Volunteers Overlaps Primary Data Sets Online streams Why? How many? Express stream Data flow overview Analysis Physics signature What is my trigger? Where do I find the data? Experiment dependent Sample location & content An aside: Data formats RAW, RECO, AOD, ESD, TAG… What do I need? What can I afford? Where is it? Efficiency measurements backup triggers, samples How fast can I run over my sample? Vertical and Horizontal skims An Example Table of Contents HCPSS - Triggers & Analysis

3. Rates… Cross Section: σ(pp) = 70 mb Interaction Rate, R = 7x108Hz Bunch Spacing:t= 25 ns • Physics Cross Sections: • Inelastic: 109Hz • W→l ν: 102Hz • t t production: 10 Hz • Higgs (100 GeV/c2): 0.1 Hz • Higgs (600 GeV/c2): 10-2Hz • 250 GeV ET Jets - 1kHz • Rejection needed: 1:1010-11 HCPSS - Triggers & Analysis

4. Time to think?Bunch Spacing… Less time to think, MUCH more to think about… HCPSS - Triggers & Analysis

5. From P. Sphicas, Trigger @LHC talk - i HCPSS - Triggers & Analysis

6. From P. Sphicas, Trigger @LHC talk - ii HCPSS - Triggers & Analysis

7. What do we trigger on? General considerations • Basics: • Hadron colliders produce mostly low momentum hadrons • Most interesting Physics has signatures involving large transverse energy (ET) particles. ==> Require high ET on reconstructed particles • Basic objects used for trigger: • Electrons, Photons, Muons, Jets, Missing Et • Approximate thresholds and associated rates: • Single muon with PT>20 GeV - 10kHz • Double muon PT>6 GeV - 1kHz • Single em cluster with ET>30 GeV - 10-20 kHz • Double em cluster with ET>20 GeV - 5 kHz • Single jet with ET>300 GeV - 0.2-0.4 kHz The more complexity one adds to the a signature - the lower the rate, and hence the required threshold The more complex the signature is - the harder it is to understand… HCPSS - Triggers & Analysis

8. HLT Trigger Table - Example (CMS) HCPSS - Triggers & Analysis

9. Detector commissioning Timing Cabling … Comish. Low level reco. Val. hits, segments, clusters Calibrate Noise, 0-suppression Comish. Object reco. Establish e, m, jet… IDs Define basic eff. - Z signal Measure rejection Isolation! Counting experiments Cross section measurements Raw Data Latch-all (no 0-suppression) Basic detector DQM software Local/global daq Raw and RecHits Local geometry, DB access Low level reconstruction software Establish 0-suppression asap! Raw, RecHits and Reco Detector geometry, DB, Ca/Al… Full reconstruction software (HLT) Basic trigger, Access to data Absolute efficiencies (tracking…), MC scale factors Luminosity Evolution of Ana goals, implications… HCPSS - Triggers & Analysis

10. Trigger Path • The “name” of the sequence of requirements that resulted in an event being recorded: • L1 accept • HLT confirmation • Object type(s) and threshold(s), cut(s) (things like: emu_20_20_iso_met_50 or maybe hipt_emu_met) • There has to be a bit for each one. • Defines how events are classified (immutably!) • Implication: complete exploration of all L1 accepts HCPSS - Triggers & Analysis

11. Pre-requisites, Volunteers • Pre-Requisite: Only muons that have a L1 accept are pursued in the HLT. Moreover, only that region is reconstructed. • Volunteer: A muon “found” in the HLT, without a corresponding L1 accept cannot result in a trigger • this cannot happen if we do “seeded” (on L1 muon track) reconstruction in HLT, but can happen if we do global reconstruction. HCPSS - Triggers & Analysis

12. Overlaps • A frequently asked question is: • What is the overlap between Primary Data Sets? • Recall that the overlap between data sets is a result of the overlap between trigger paths. How big is it? How big should it be? • Up front overlap - express stream. • An experiment decides how big it is (~10%) • Completely controlled • Additional duplication occurs due to Physics but is very small in comparison. • An e-mu-met event will (hopefully) go to three data sets and we want them to! • But (sadly) there are few of these… • Can have huge overlaps - need good design of trigger table • One can have as big an overlap as one can afford. HCPSS - Triggers & Analysis

13. Primary Data Sets • It is easy to foresee about 50 primary datasets to be identified during the HLT processing, each following a strict trigger path (L1 and the appropriate HLT confirmation of it). • How many will be needed? • There is danger in too many, and also in too few… • Serious Physics Coordination issue! • As a Data Management artifact in the Online farm, these 50 primary datasets may be grouped into about 10 streams constructed to be roughly of similar sizes and contain more or less related primary datasets. • These streams have no (physics) significance outside of the Online-to-Offline data management context. HCPSS - Triggers & Analysis

14. Streams (online, intermediate) • One can imagine the following example of streams definition: • Jet data stream • electron/photon • Muon, tau/MET • calibration • min bias • … • Where for example the ele/photon stream will contain the primary datasets for inclusive electron as well as the di-electron triggers of various thresholds (some may be pre-scaled) and the closely related photon triggers. • These primary datasets should contain back-up triggers (primary datasets) to assist in understanding the efficiency and rejection of the main ones (they will be usually looser and pre-scaled). HCPSS - Triggers & Analysis

15. Basic characteristic: Low production rate signal Large background Many, small channels to assemble Search for top quark Pick a signature: (di-leptons, lep+jets…) pp-->tt+X and tt-->WbWb Where: W-->e W--> Final States: -lepton pair, two b jets - lepton, 2 b-jets, 2 q-jets Why limit oneself to only leptonic W decays? Why not look at all W and Z decays? (leptonic rates very low) … >> It’s the rates! Analysis steps: Find corresponding triggers: Inclusive electron, muon Di-electron, muon Maybe others (bb+met), but much harder (why?) Define the samples to use: W & Z samples (to e and mu) Which level of information is needed? 4 vectors? RAW data? Something in between?? Where is it to be found? How big is it? How long does it take to run over it? Can it be “reduced”? End-to-End example HCPSS - Triggers & Analysis

16. Triggers & Data sets used Relied primarily on inclusive electron and inclusive muon triggers Many backup triggers needed: Various inclusive jet samples for jet corrections Gamma-jet sample for E-scale W-notrack trigger for tracking efficiency Jet50 sample for b-tagging MC scale factor Many many more A “family” of analyses Three main classes Di-lepton Lepton+jets All hadronic All predicated on the basic trigger path, or primary data set. Finer split within each Electron, Muon or jets as “anchor leg” (trigger requirement) additional features (e.g. vertex b-tagging, SLT…) Notes from the search for top HCPSS - Triggers & Analysis

17. Sample definitions:Inclusive Electron/Muon Samples HCPSS - Triggers & Analysis

18. W selection HCPSS - Triggers & Analysis

19. Jets and Met in top events HCPSS - Triggers & Analysis

20. b jets from top decays HCPSS - Triggers & Analysis

21. “Soft” leptons in top decays HCPSS - Triggers & Analysis

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