# Presentation: 547717

##  Z BF using

** ****Z ********BF using**
** ******** ****hadronic events **

- Silke Duensing
-  Aug 8th, 2003

##  Decay and Identification

**hadronic ******** decays**

- No L1 track trigger
- Use leptons
- Choose for muon

****** ****type**

****** ****type**

## Z  hadronic 

## hadronic Reconstruction 

- Understanding the Tau
- Reconstruction

## hadronic Reconstruction 

- Understanding the Tau

- Track matching
- Tracks, pT > 1.5 in 0.5 cone
- 2nd, 3rd track:
- consider invariant mass + charge

**3 prong tracking**
**efficiency:**
**unknown**

**1 prong as 3 prong: pickup tracks**
**3 prong as 1 prong: inefficiency**

## hadronic Selection (-type) 

## Signal sample and Trigger

- Select had candidates:
- Clean, high pT muon
- Muon is isolated
- Cut on max(ET Halo +  pT trk in 0.5)
- Used cut is used in optimization of cut
- Require with uncorrected ET > 10 GeV

**MU_TAU10_L2M0**
- Trigger contains muon terms at L1 and L2
- L1: + 1 trigger tower (0.2x0.2 in )     above 5 GeV CJT
-  -specific term at L3
- a L3 track > 5 GeV
- Require a match of tau to trigger objects

## hadronic LLrigger

- Understanding the Tau
- Reconstruction
- Separation into Types
- Selection using Square Cuts
- Trigger Efficiency
- Not many taus in data
- Thus use QCD jets that are tau-like
- Checked “box”-result with profile weighting

##  Towards the Z had cross-section

- Muon+Tau Efficiencies
- Isolation
- Trigger Efficiency
- Background
- From:
- QCD
- W 
- Z  ->opposite sign!
- WW
- tt

- same chg = opp chg

- small, from MC

- Reject w. cuts

##  Backgrounds (I)

- From:
- QCD
- W 
- Z  ->opposite sign!
- WW
- tt

- same chg = opp chg

- Reject w. cuts

- Additional (> 0.5) loose mu (in fid region)

- Isolated track w. pT > 15 (in non-fid region)
- Use Z in datato get # of remaining events in signal

##  Background (II)

- From:
- QCD
- W 
- Z  ->opposite sign!
- WW
- tt

- same chg = opp chg

- small, from MC

- Reject w. cuts

- Use MC muon, account for data
- efficiencies, use tau + electron
- efficiencies

##  Backgrounds (III)

- From:
- QCD
- W 
- Z  ->opposite sign!
- WW
- tt

- same chg = opp chg

- small, from MC

- Reject w. cuts

##  The candidates in the  case 

- ...are expected to be
- back-to back

- ...and have an invariant
- mass of the
- muon and tau
- 10<m<60 GeV

##  Putting the pieces together

## Systematics on selection

- Three sources of systemtatics in selection:
- JES when cut on ET/pT
- Tracking efficiency for track isolation
- MC modeling for shape cut

- JES: vary E by 10%
- Tracking isolation
- Compare Z  MC and data
- Shape cuts:
- Look at os – ss events,
- Correct with CM efficiency                			 constant?

## Systematic check: electrons as taus

- For main seletion:
- Take electron factor from MC
- Check with cross section
- Including electron cut
- : fractor 1.3

## Isolated muon

- Muon is isolated
- Muons from Z  are like muons from Z 
- Signal: use Z mm
- Background: events  with low MET
- Used cut is used in optimized

## hadronic Lrigger

- Understanding the Tau
- Reconstruction
- Separation into Types
- Selection using Square Cuts
- Trigger Efficiency
- Not many taus in data
- Thus use QCD jets that are tau-like