HLT Selection at Phase II John Baines

Assumptions Phase II: 5-7 x10 34 Much of what is currently done at Level-2 will now be done at Level-1, incl. – Fine granularity calo information – Topolology – L1track How to maintain rejection at HLT? – Not enough to simply repeat L0+L1 selection with better resolution – Need new, more exclusive selections=> look to offline Rates: – L1 Rate : 200kHz – Aim for full-event readout at L1 rate? => full-event reco. at L1 rate. – ~10kHz o/p rate from HLT ?

HLT Selection in Phase II LoI HLT sw upgrades needed to : – Match detector upgrades: ITK … – Maintain HLT rejection with upgraded L0+L1 More offline-type selections Greater reliance on multi-object triggers (Leptons,Jets,B-tag,MET) Utilize new computer hardware: – code parallelisation, use of many-core/co-processors Near offline quality reconstruction of tracks and clusters – Calo: clustering, noise suppression, pile-up removal – ID: full conditions info, add tracks with no L1 seed – Full event reco: Primary & secondary vertex reconstruction Pile-up suppression Near offline quality reconstruction of trigger objects – Offline jet algorithms: track-based jets, Jet Vertex Fraction… – New ideas for MET? – e/gamma : offline algorithms, Brem. Recovery, converted photons – Tau: secondary vertex reco. – B-jet: primary & secondary vertex reco. Offline algos. Parallelisation: – At the event/RoI level : changes to framework – Within algorithms e.g. at track/cluster/loop level

HLT Selection in Phase II LoI Status: Currently just text. – Need a few plots/table illustrating how ~factor 20 rejection will be achieved. => Need help from signatures to add missing material Chose one or two/few channels as examples? Use few signatures as examples? E.g. MET REFfinal and offline B-jet? B-Jet tagging What can be done comparing Offline/HLT with existing samples at 1=2x10^34? What is available at higher p.u. ? e.g. ID only datasets for B-jet tagging =>

Summary Much of the HLT work not linked to specific upgrade phase: – Changes for evolving computing hardware – Move to more offline-type selections – Changes to address increasing luminosity & pile-up Some work specific to Phase II: – Changes matching detector upgrades e.g. ITK – Changes matching L1 upgrade L0+L1 track – Selections and menus for 7X10^34 – Phase II LoI, TDR Need to get organized

Additional Material

Example Offline Selections - 1 Higgs self-coupling studies HH --> bb + WW: – Lepton p T > 25 GeV, 4 jets with p T > 25 GeV, al least one B-tagged, MET > 30 GeV (20 GeV for mu) – H mass window: (H 1 ->bb) = jet_1 + jet_2, H 2 ->WW= jet_3 + jet_4 + Wlepton – Cuts on angular distribution :  R(bb),  (bb) HH -->  bb: – p T (b1)>40 GeV, p T (b2)>25GeV, p T (  1)>25GeV, p T (  2)>25GeV – Higgs mass cuts, Angular cuts:  R(  b)  R(  )  R(bb) VBF H->  Tmiss  forwards jets -> veto central jets – 2 leptons, 2 forward jet E T >60,50GeV – central jet veto with 60GeV or 50GeV (|  |>2.1) or 30GeV (|  |<2.1) – Track information used for: central veto (factor 2 in bg) & forward jet tagging Leptons + jets + b-tag +MET Photons+Jets+b-tag leptons+forward Jets +central jet veto VV Scattering W L W L scattering: – e pt > 40GeV or mu pt > 40GeV – One AntiKt6 jet in the central region pt > 300GeV, MET_Reffinal_et > 40GeV Higgs Spin/CP measurements H‐>ZZ‐>4l angles (also H->  Top physics Top FCNC: (t → qγ, t → qZ) other t SM decay t → bW. 4 leptons Lepton+jet+MET Leptons+Jets + b-tag

Example Offline Selections - 2 Exotics: Dilepton resonance : heavy Z-like resonance – two same-flavor leptons pt > 25 GeV, MET, jets ttbar resonances: decays with leptons, b-jets, MET SUSY: Higgs production is SUSY cascades: – search for Jets + MET + lepton + H(->bb) – 2 Bjets pT>40 other Bjets pT>60 MET>400 HT>500 Stop: 1-lepton(pT>25) + MET + 4jets (pT jets > 100, 80, 50, 50) and 2-lepton (+MET,jets) Gauginos : MET>300 Leptons + jets + b-tag +MET Leptons + jets +MET Leptons + jets + b-tag +MET

1) Improve on Level-1 selection Calorimeter: Better calibration: How close can we get to offline? – Update calibration during run based on date from earlier in run. Noise suppression – Identification and removal of cal energy from noise spikes Tracking: Corrections for Dead/noisy modules : – conditions updates during run. – Flag as much as possible via data Better track parameter resolution: – Better conditions info., complete field-map, more sophisticated track fit – Use of all ITK info (4-8 pixel hits, Si strips including overlaps) Reconstruction of tracks missed by L1Track: – Tracks not from IP : – conversions, long lived particles – Tracks below ITK threshold – Difficult regions : inhomogeneous field, dead/noisy modules, forward region... Event-by-event primary vertex reconstruction ->allows d0 cut (requires tracking for full event)

2) Offline-quality object reconstruction Leptons: Offline-type selection: multivariate analysis Electrons: Bremstrahlung correction Photons: reconstruct converted photons Tau: 3-prong: Secondary vertex reconstruction Primary vertex reco -> allows d0 cut Jets: Offline jet algos- Full-scan Calorimeter-based pile-up subtraction Tracking: Vertex fraction, track-based jets

MET Refine L1 MET at HLT: Need maximum information : access to calo cell energies. Offline MET algorithm: currently METrefFinal : object-based (cell energies calibrated according to object they are associated with) => better turn-on – But not clear if this is still the best algo for phase-II lumi -> needs study Pile-up subtraction: calo-based: parameterise p.u. contribution Track based: associate clusters to p.u. : needs study to evaluate. But can we achieve a low enough MET threshold at L1 at all? Want thresholds <~120GeV => aggressive noise cuts (sigma <2GeV, see David Strom’s talk: – => investigate techniques to subtract p.u., promising technique: – SumET v. SumE linear for p.u. => parameterise and define new variable ETXS as difference between SumET and value from parameterisation – If we can’t achieve low enough thresholds at L1, could calculate HLT MET for events triggered e.g. via lepton trigger.

3) Additional Information at HLT Secondary vertex reconstruction B-tagging Full event reconstruction would allow: – Jet reco based on full-scan – Reconstruct objects not in L1 RoI => increased multiplicity requirement e.g. 2 high p T leptons -> 2 high pT leptons + 1 low p T Possibility of HLT MET i.e. – No MET trigger at L1 – L1 e.g. lepton(s) & jets

More exclusive selections: multi-object To do more, need to look to physics selections Build triggers from combination of jets, jets with b-tagging, leptons, MET Add topological triggers : mass cuts: Z,H, geometrical cuts (  R(ll),  R(lj),  R(jj)) Following based on examples (Non-exhaustive list): Measurement of Higgs Properties (mass, spin, couplings) Measurement of massive gauge boson pair scattering at high energies Measurement of top quark properties (mass, spin, couplings, W helicity, etc) Other EW measurements (e.g. W mass, TGCs) Searches for massive particles/new interactions (SUSY, exotics) See: 2nd Workshop "ATLAS Input to the European Strategy"