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Review of Charged Higgs Trigger strategies. Simone Gennai Centro Studi Enrico Fermi, Roma. Trigger: the first step towards an analysis. Problem to face: reduce a huge amount of non interesting events and do it in a short time !. At Tevatron: - s Inel ~ 50mb - s top ~ 7pb

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review of charged higgs trigger strategies

Review of Charged Higgs Trigger strategies

Simone Gennai

Centro Studi Enrico Fermi, Roma

trigger the first step towards an analysis
Trigger: the first step towards an analysis

Problem to face: reduce a huge amount of non interesting events and do it in a short time !

At Tevatron:

-sInel ~ 50mb

-stop ~ 7pb

-About a factor 1/1010

Trigger rejects 99.995% of the crossings.

At LHC the situation is similar

and also the trigger systems are “similar”

Simone Gennai, Centro Studi Enrico Fermi - Roma

charged higgs @ tevatron
Charged Higgs @ Tevatron

Production:

  • Major decay modes:
    • H+->t+n
      • Most important
    • H+->cs
    • H+->t*b->W+bb
    • H+->W+h->W+bb
  • BR’s depend on:
    • tan b, m(H+)
  • Differ from W+ BR’s

t ->bH+ (mH < mt-mb)

Simone Gennai, Centro Studi Enrico Fermi - Roma

analysis strategies
Analysis strategies
  • Find some inconsistencies with the top decay branching ratios given from the Standard Model
    • As the BR(H+->tn) > BR(W->tn), the total number of leptons in the final state is different if the diagram with the charged Higgs is present
    • The analysis follows the top precision measurements

Simone Gennai, Centro Studi Enrico Fermi - Roma

cdf detector
CDF Detector

Simone Gennai, Centro Studi Enrico Fermi - Roma

cdf trigger system
CDF Trigger system

3 Levels Trigger:

L1 output rate = 20kHz

-Hardware (5 msec)

L2 output rate = 350 Hz

-Hardware and

Software (30 msec)

L3 output rate = 75 Hz

-Completely Software

Simone Gennai, Centro Studi Enrico Fermi - Roma

cdf charged higgs
CDF Charged Higgs

Trigger strategies are the same as the one used in the top measurements:

High PT Lepton

Some samples used Jet triggers or relaxed cuts lepton trigger for efficiency studies.

Look at four tt final states:

  • di-lepton + jets
  • lepton + jets (=1 b-tag)
  • lepton + jets (≥ 2 b-tags)
  • lepton + tau + jets

Simone Gennai, Centro Studi Enrico Fermi - Roma

high pt electron trigger
High Pt Electron Trigger
  • |hdet |<1.0
  • Level 1
    • Calo Tower energies are summed to form trigger towers
    • At least one tower must have:
      • ET > 8 GeV
      • Ehad/Eem < 0.125
      • At least one COT (XFT) track with pT > 8 GeV pointing at tower
  • Level 2
    • Clustering algorithm combines tower energies to form a cluster
    • Cluster must have:
      • XFT track with pT > 8 GeV matched to seed tower of cluster
      • ET > 16 GeV
      • Ehad/Eem < 0.125

Simone Gennai, Centro Studi Enrico Fermi - Roma

high pt electron trigger1
High Pt Electron Trigger
  • Level 3
    • EM cluster reconstructed by offline algorithm must have:
      • ET > 16 GeV
      • Ehad/Eem < 0.125
      • 3D COT track with pT > 9 GeV pointing at the cluster
  • Typical Rates
    • For L=2.5x1031 cms-2s-1:
      • L1 accepts 25 Hz
      • L2 accepts 3 Hz
      • L3 accepts 1 Hz

Simone Gennai, Centro Studi Enrico Fermi - Roma

d0 analysis fully hadronic final state
D0 analysis: fully hadronic final state
  • It considers the following cases:
    • Both top quarks decay into H±(->tn)
      • Two tau jets are present in the final state
    • One top quark decay into H± and the other into W
      • Only W hadronic decays are considered
      • 1 tau jets and light quark jets are present in the final state

Simone Gennai, Centro Studi Enrico Fermi - Roma

d0 analysis jet trigger
D0 analysis: Jet trigger
  • Level 1
    • 4 trigger towers ET > 5.7 GeV
    • 3 large tiles ET > 15 GeV
    • Cumulative efficiency: 98 % (on top events)
  • Level 2
    • 5 jets R = 0.3
    • |h| < 2.5
    • ET > 10 GeV, HT > 120 GeV
    • Cumulative efficiency: 92 %
  • Level 3
    • HT > 115 GeV from R = 0.5 jet cones
    • |h| < 2.5
    • ET > 8 GeV
    • Cuts for spurious jets
    • Cumulative efficiency: 87 %

Simone Gennai, Centro Studi Enrico Fermi - Roma

lhc analysis
LHC analysis
  • Most important production channels
    • gb->tH- (for mH > mtop) ,t->bH- (for mH < mtop, in top pair production)
      • Lepton from W decay can be used to trigger on.
  • Two possible decay mode for the charged Higgs:
    • H-->t n-> hadrons + n
      • (Relevant in the complete mass range for high tanb)
      • A dedicated Tau Trigger has been developed for the fully hadronic final state
    • H-->tb -> qq’ + b + b
      • (Relevant for mH- >mtop )

Simone Gennai, Centro Studi Enrico Fermi - Roma

schematic view of the cms detector
Schematic view of the CMS detector

Simone Gennai, Centro Studi Enrico Fermi - Roma

atlas and cms trigger system
ATLAS and CMS Trigger System

Multi Level Trigger System

Trigger after Level 1 must have rejection power ~1000.

“Triggerable” objects are:

Electrons/gammas, muons, jets, Tau jets (hadronic tau decay), missing transverse energy, etc. etc.

Combined trigger (e or m + t) are also forseen.

Simone Gennai, Centro Studi Enrico Fermi - Roma

h tb wbb qq bb
H+->tb -> Wbb->qq’bb

The top quark produced in association with the charged Higgs provides the lepton for the trigger.

electron trigger

Selections are based on pT cut and isolation criteria.

Total L1 Rate ~ 5kHz

Muon isolation

Simone Gennai, Centro Studi Enrico Fermi - Roma

electron trigger selection

-Region of Interest (,, pT and energy sum of candidate object)

-Coarse granularity info from calorimeter

Event Display

HZZ 2e2

L1 calo

L2 calo

  • Seeded by L1 RoI
  • Full granularity
  • Calo (shower shape) and tracking

L2 tracking

Electron Trigger Selection

-Seeded by L2 or full event access

-refined alignment and calibration data

-Calorimeter and tracking

- offline-like algorithms

EF calo

EF tracking

Simone Gennai, Centro Studi Enrico Fermi - Roma

electron photon trigger

e25i for ET>22 GeV

50% of the clusters come from real electrons

Efficiency has flat distribution for high ET

Electron/Photon Trigger

Trigger Selection is performed on an event basis and includes the double and single object trigger items for electrons and photons.

TriggerEfficiency Rate

e25i 76.2 % 46 4 Hz (low)

TriggerEfficiency Rate

2e15i 60 % few Hz

Simone Gennai, Centro Studi Enrico Fermi - Roma

cms muon l1 trigger
CMS Muon L1 Trigger

Simone Gennai, Centro Studi Enrico Fermi - Roma

gg tbh qq bb t jet n
Gg->tbH+->qq’ bb tjetn

Single Tau trigger has been developed for this fully hadronic final state. Usefulfor high values of the Higgs boson mass

See Casado’s talk for more details

Simone Gennai, Centro Studi Enrico Fermi - Roma

lep production mechanims low mass higgs boson
LEP: Production mechanimsLow mass Higgs boson

Trigger requirement are very loose

Simone Gennai, Centro Studi Enrico Fermi - Roma

delphi trigger system lep i
Delphi Trigger system (LEP I)
  • T1 & T2 (hardwired decision, fully syncronous with the Beam Cross Over
    • T1: 90kHz -> 800 Hz (11 msec)
    • T2: 800 Hz -> 4 Hz
    • T3 & T4 Software driven trigger
    • T3: 4 Hz -> 2 Hz
    • T4: reduces further with quality constraint

Simone Gennai, Centro Studi Enrico Fermi - Roma

doubly charged higgs h
Doubly-charged Higgs (H±±)
  • Short lived particle:
    • Most of the analysis are focused on ee, mm decays (also em, et at HERA)
      • Single or double lepton trigger is used
  • Long lived particle:
    • It seems like an heavy muon
      • Inclusive muon trigger is used

Simone Gennai, Centro Studi Enrico Fermi - Roma

conclusions
Conclusions
  • The Trigger is the first step of the analysis
    • At the hadron collider it is foundamental for new physics discovery
  • Most of the trigger strategies share the same logic
  • In the future triggers on hadronic tau decays will be have a keyrole in several analysis

Simone Gennai, Centro Studi Enrico Fermi - Roma

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