# Presentation: 516274

## Status of the Higgs Sensitivity Studyin ZHbb 

**Status of the Higgs ****Sensitivity Study****in ****ZH********bb**** **

**Boaz Klima**
**Fermilab**
**For the ****DØ**
**Higgs Sensitivity Group**
**Washington DC**
**June 19, 2003**

## IIa_LowL - used full GEANT simulation of the DØ detector for Run IIa (2E31), which reproduces most aspects of the current data
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 today’s best understanding of hardware and software
No time to fully optimise analyses or use relatively new analysis techniques – it will only get better

- 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 today’s best understanding of hardware and software
- No time to fully optimise analyses or use relatively new analysis techniques – it will only get better

**General Strategy**

## Results

**The ****DØ Team:** Boaz Klima (Fermilab, chair), Levan Babukhadia (Stony Brook), Wade Fisher (Princeton), Anna Goussiou (Imperial College), Qizhong Li (Fermilab), Meenakshi Narain (Boston univ.), Richard Partridge (Brown univ.),  Flera Rizatdinova (Kansas State), Chris Tully (Princeton), Andre Turcot (BNL) + John Hobbs (Stony Brook) and Avto Kharchilava (Notre Dame)

## Higgs Sensitivity Estimate for ZHbb  (Run IIb, L~2E32, mHiggs=115GeV)

-  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

- Direct comparison with the 1999 study

## ZHbb AnalysisUpdated Cross Sections

## Higgs Sensitivity Estimate for ZHbb(new x-secs, trigger eff., QCD)

-  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

- Today’s results compared with 1999 study

## Higgs Sensitivity Estimate  (Run IIb, function of mHiggs ) 

- Expected sensitivity in 1 fb-1

- ~20% less luminosity is needed compared to the 1999 study

- Today’s results compared with 1999 study

## 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 we’ll need more luminosity
Whatever bad happens to the detector, which is not currently being simulated...
Good news
Smart combination of results, using mass distributions rather than counting, will buy us ~20% in luminosity wrt 1999 study
We have more new analysis techniques available today, e.g. see the recent mtop measurement (x2 in luminosity)
Our analysis is by no means fully optimised!
Looks good...

**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 we’ll need more luminosity**
**Whatever bad happens to the detector, which is not currently being simulated...**
- Good news
**Smart combination of results, using mass distributions rather than counting, will buy us ~20% in luminosity wrt 1999 study**
**We have more new analysis techniques available today, e.g. see the recent m****top ****measurement (x2 in luminosity)**
**Our analysis is by no means fully optimised!**
- Looks good...

**Comments ****on  ZH********bb **

## 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...

**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...**

**Outlook**