Status of the Higgs Sensitivity Study

1
Status of the Higgs Sensitivity Study
CDFs set of flags (banner or individuals)
Boaz Klima Fermilab For the CDF and DØ Higgs
Sensitivity Group Washington DC June 19, 2003
2
Outline

• General comments
• The Strategy
• WH and ZH Analyses
• Combination of Channels
• Conclusions

3
The Run II Physics Program

• The Higgs search is very important
• By no means this is the only thing we are (and
  plan on) doing
• There is an extremely rich physics program -
  every time we double the integrated luminosity we
  open a new window (SUSY, LED, )
• This is the frontier of HEP for the next decade
  or so
• We should be taking advantage of this unique
  situation in every possible way invest in
  accelerator/detectors
• Fermilab and the two collaborations are
  committed to produce the most exciting physics on
  earth, if supported properly

Conclusion - the Run II physics program at the
frontier of HEP is very rich lets take full
advantage of this unique opportunity
4
The Tevatron Experiments

• The experiments are up and running efficiently -
  we are collecting high-quality data at reasonable
  rates
• All data are being processed by the
  reconstruction program online
• Physics analyses are being performed in many
  areas
• Re-establishing old measurements and limits
• Testing the SM at a new/higher ECM
• New angles, new ideas,
• Looking for surprises hints for physics beyond
  the SM
• Its very
• exciting!

Conclusion - the experiments are running very
well and producing world-class physics results
(stay tuned for LP03,)
5
Top Quark Search in Run I

• Prior to Run I (1992) theorists
• and experimentalists estimated that
• Our sensitivity (mass reach) is
• going to be lt 125 GeV
• Our Tevatron mass resolution
• (uncertainty) will be 13 GeV
• The Top quark was discovered by
• CDF/DØ in 1995
• At a mass of 175 GeV !
• Our current uncertainty on the
• top mass is 4 GeV !!
• LEP had similar experience
• Other labs/experiments too

Conclusion - the sensitivity is always better
than estimated prior to the Run
6
AnalysisStrategy
7
What? Why?

• We were asked by DOE about 6 months ago to
  provide a new estimate (plot?) for the Higgs
  sensitivity during Run II based on our current
  understanding of detectors and analysis
  components and their projected performance as
  luminosity becomes available
• Timescale June 03 very short!
• What can we do?
• No time for complete analysis!
• Collaborations are extremely busy with Run IIa
  tasks
• Were all in this together

8
Strategy (CDF/DØ )

• Form a CDF/DØ working group (minimal overlap with
  current mainstream efforts)
• CDF Members Kroll, Winer, (need all names here)
  Higgs group convenors
• DØ Members Babukhadia, Fisher, Goussiou, Klima,
  Li, Narain, Partridge, Rizatdinova, Tully,
  Turcot Higgs group convenors
• Very few, very talented, very productive
• Base on Run II Working Group study
  (hep-ph/0010338)
• Split the work wherever possible, e.g. CDF -
  lnbb, DØ - nnbb (the most sensitive modes), other
  decay channels?
• Time permitted, add new channels, e.g W/Z (/H?)
  decaying to t, H WW, get smart in the
  analysis,
• Pleasant experience working together

9
Tactics

• IIa_LowL - used full GEANT simulation of the DØ
  detector for Run IIa (2E31), which reproduces
  most aspects of the current data (yes, were
  still fixing problems)
• IIa_HighL same in high luminosity environment
  (2E32)
• IIb_HighL same using full GEANT simulation of
  the DØ detector (mainly new SMT for b tagging)
  for Run IIb in high luminosity environment (2E32)
• Predicting future performance based on todays
  best understanding of hardware and software
• No time to fully optimise analyses or use
  relatively new analysis techniques it will only
  get better

10
Documentation

• Detailed studies on
• Triggers
• B tagging
• Di-jet mass
• QCD background
• WH and ZH analyses
• Endgame
• are nicely documented notes and
  presentations
• See in
• http//www-d0.fnal.gov/Run2Physics/higgs_sensitivi
  ty_study.html
• (Linked from our Physics main web page in
  News)

11
Resultsfor WHlnbb
12
Higgs Sensitivity Estimatein WHlnbb
Direct comparison with the 1999 study

• Assume 100 QCD
• contribution (a la SHWG)
• NO trigger applied
• 35 b-tagging eff
• 1 tight 1 loose tag
• 32 for 2 tight tags
• Number of events
• estimated in 1 fb-1

50 less luminosity is needed compared to the
1999 study
13
WHlnbb AnalysisUpdated Cross Sections
14
Higgs Sensitivity Estimatefor WHlnbb
Todays results compared with 1999 study

• Trigger efficiencies
• applied for this analysis
• QCD as calculated in
• current study
• 35 b-tagging eff
• 1 tight 1 loose tag
• 32 for 2 tight tags
• Number of events
• estimated in 1 fb-1

28 less luminosity is needed compared to the
1999 study
15
Higgs Sensitivity Estimate
Todays results compared with 1999 study
Expected sensitivity in 1 fb-1
20 less luminosity is needed compared to the
1999 study
16
Comments on WHlnbb

• Bad news
• Our double b-tagging efficiency for Run IIa is
  currently estimated to be at X compared to Y
  using our IIb SMT if we do not upgrade well
  need more luminosity
• Whatever bad happens to the detector, which is
  not currently being simulated
• Good news
• Smart combination of results a la LEP (CLS vs
  straight counting) will buy us 20 in luminosity
• We have more new analysis techniques available
  today
• Our analysis has not been optimised!
• Looks promising

17
Resultsfor ZHnnbb
18
Higgs Sensitivity Estimate for ZHnnbb (Run
IIb, L2E32, mHiggs115GeV)
Direct comparison with the 1999 study

• Assume 100 QCD
• contribution (a la SHWG)
• NO trigger applied
• 35 b-tagging eff
• 1 tight 1 loose tag
• 32 for 2 tight tags
• Number of events
• estimated in 1 fb-1

50 less luminosity is needed compared to the
1999 study
19
ZHnnbb AnalysisUpdated Cross Sections
20
Higgs Sensitivity Estimate for ZHnnbb(new
x-secs, trigger eff., QCD)
Todays results compared with 1999 study

• Trigger efficiencies
• applied for this analysis
• QCD as calculated in
• current study
• 35 b-tagging eff
• 1 tight 1 loose tag
• 32 for 2 tight tags
• Number of events
• estimated in 1 fb-1

28 less luminosity is needed compared to the
1999 study
21
Higgs Sensitivity Estimate (Run IIb, function
of mHiggs )
Todays results compared with 1999 study
Expected sensitivity in 1 fb-1
20 less luminosity is needed compared to the
1999 study
22
Comments on ZHnnbb

• Bad news
• Our double b-tagging efficiency for Run IIa is
  currently estimated to be at 19 compared to 32
  using our IIb SMT if we do not upgrade well
  need more luminosity
• Whatever bad happens to the detector, which is
  not currently being simulated
• Good news
• Smart combination of results a la LEP (CLS vs
  straight counting) will buy us 20 in luminosity
• We have more new analysis techniques available
  today, e.g. mtop
• Our analysis is by no means fully optimised!
• Looks good

23
Combined Resultsfor nnbb, llbb, and lnbb
24
Higgs Sensitivity
Relative Contributions (a la LEP)
ZH
WH
25
Higgs Sensitivity (nnbb llbb lnbb CLS comb)
Combined DØ/CDF Result
5s discovery 3s evidence 95 CL exclusion
26
More Comments

• Bad news?
• We still have to work hard to get to the
  assumed/expected sensitivity (we will!)
• We may be statistically unlucky
• Good news
• We may be statistically lucky
• We know it will get better (tools,
  optimisation,)
• We expect it to get much better (remember Top in
  Run I!)
• Great Start

27
Conclusions

• We are excited to work at HEPs frontier program
• Both collaborations are committed to producing
  exciting physics until the end of the decade
• The experiments are running very well and
  producing world-class physics results
• This study proved that the Higgs reach at the
  Tevatron is at least as good as projected 4 years
  ago
• The Higgs sensitivity will improve over time as
  we get more data, better understand our
  detectors, use smart analysis techniques, and
  develop new ideas
• We are looking forward to a long and exciting
  Physics program at the worlds frontier energy