# Presentation: 684092

## W Charge Asymmetry

- Cigdem Issever, Adam Scott and David Stuart
- UCSB

- CDF-Note 6282, Measurement of the W->e nu Charge Asymmetry
- CDF-Note 6108, Alignment of the Plug Calorimeter
- CDF-Note 6412, QCD Background of Plug W’s

- Cigdem Issever, UCSB

## W Charge Asymmetry

- Cigdem Issever, UCSB

## W Charge Asymmetry

- Cigdem Issever, UCSB

## 
Plug electron identification with Phoenix SiTracking
Plug and Silicon
Charge determination

**Plug electron identification with Phoenix SiTracking**
**Plug and Silicon**
**Charge determination**
** **

**Essentials for W Charge Asymmetry**

- Cigdem Issever, UCSB

## Charge ID

**Charge determination critical.**
**Charge misidentifation fq=wrong/total dilutes the asymmetry.**
**Correct for it **
**A****true**** = A****meas****/(1-2fq)**
**So, make fq small and measure it.**
**MC predicts fq ~ 1%.**
**But MC has no residual mis-alignments, etc-->**
**We must measure fq in data.**
**Measured fq(eta) with Z->e+ e-**

- Cigdem Issever, UCSB

## Baseline electron selection with COT or Phoenix Track and Et>25GeV.
Phoenix Track selection optimized for small fq
# SiRPhiHits >= 4
Chi2 < 8
Delta Chi2 > 0.5
Pull < 0.4   
              (Chi2_Seed/dof for track with lesser Chi2_total/dof)
              (Chi2_Seed/dof for track with greater Chi2/dof)
80 < Mee<100 GeV and compare central Qtag

- Phoenix Track selection optimized for small fq
- # SiRPhiHits >= 4
- Chi2 < 8
- Delta Chi2 > 0.5
- Pull < 0.4
-               (Chi2_Seed/dof for track with lesser Chi2_total/dof)
-               (Chi2_Seed/dof for track with greater Chi2/dof)
- 80 < Mee<100 GeV and compare central Qtag

**Z Event Selection **

- Cigdem Issever, UCSB

## Mee Distribution

***Data (******west******, ******east******)***
***MC***

- CDFII Preliminary ∫Ldt=170/pb

**Central**

**Plug**

- CDFII Preliminary ∫Ldt=170/pb

- Corrected energy scale in MC

- Cigdem Issever, UCSB

## Charge Mis-ID Rate

**Charge Mis-ID Rate**

**fq****COT**

**fq****PHX**

- Errors calculated with Bayesian prescription; CDF5894

- CDFII Preliminary ∫Ldt=170/pb

- Cigdem Issever, UCSB

## Baseline electron selection w/ PHX track. 

-    ET>25 GeV
-    Missing ET > 25 GeV
-    50 < MT < 100 GeV/c2
- No other EMO with ET>25 GeV
-    to suppress QCD and DY

**W Event Selection **

- Cigdem Issever, UCSB

## Kinematic Distributions: MT and ET

- CDFII Preliminary ∫Ldt=170/pb

- Plug

- Central

- Plug

- Central

***Data (******west******, ******east******)***
***MC***

- Cigdem Issever, UCSB

## Kinematic Distributions: MET and 

**Kinematic Distributions: ME****T ****and ******

- CDFII Preliminary ∫Ldt=170/pb

- Plug

- Central

***Data (******west******, ******east******)***
***MC***

****

- Cigdem Issever, UCSB

## Kinematic Distributions: 

**Kinematic Distributions: ******

- CDFII Preliminary ∫Ldt=170/pb

- Plug

- Central

***Data ***
***MC***

****

****

- Cigdem Issever, UCSB

## Raw Asymmetry

**Raw Asymmetry**

- CDFII Preliminary ∫Ldt=170/pb

- Curve is just a fit to guide the eye.

- Cigdem Issever, UCSB

## Raw Asymmetry

- CDFII Preliminary ∫Ldt=170/pb

- Curve is just a fit to guide the eye.

- Cigdem Issever, UCSB

## Background

-  W    etrippled statistic)
-       Asymmetric, measured from MC
-  Z e+e-
-       Asymmetric, measured from MC
-  QCD
-       Symmetric, measured from data  CDF 6412.
-              Use Iso vs MET.

**Background**

- Cigdem Issever, UCSB

##     PEM 3x3 2 or 5x9 cuts (they are correlated with Iso)

- small systematic, as long as we don’t use the
-     PEM 3x3 2 or 5x9 cuts (they are correlated with Iso)
-       upper limit by about a factor of 2.

**QCD Background systematic**

- Cigdem Issever, UCSB

## QCD fraction

***QCD fraction***

******

- We use 0.5 ± 0.25.  Becomes significant for >1.8

- CDFII Preliminary ∫Ldt=170/pb

**QCD Background**

- Cigdem Issever, UCSB

## Corrected Asymmetry

**Corrected Asymmetry**

- CDFII Preliminary ∫Ldt=170/pb
- outer error bars: total error
- inner error bars: statistical error

**Band**: correlated error from Energy scale uncertainty

- Cigdem Issever, UCSB

## CP Check

- CDFII Preliminary ∫Ldt=170/pb

- Cigdem Issever, UCSB

## A

**A******

- CDFII Preliminary ∫Ldt=170/pb

- Cigdem Issever, UCSB

## A

**A******

- CDFII Preliminary ∫Ldt=170/pb

***Compared to ******Run1****** e+*********

***FMU***

- Cigdem Issever, UCSB

## Getting more sensitivity to AW

**Getting more sensitivity to A****W**

- Cigdem Issever, UCSB

## 25 < ET < 35

***25 < E******T****** < 35***

***35 < E******T****** < 45***

**Getting more sensitivity to A****W**

- Cigdem Issever, UCSB

## AW for 25 < Et < 35 GeV

**A****W ****for 25 < Et < 35 GeV**

- CDFII Preliminary ∫Ldt=170/pb

**Band**: correlated error from Energy scale uncertainty

- Cigdem Issever, UCSB

## AW for 35 < Et < 45 GeV

**A****W ****for 35 < Et < 45 GeV**

- CDFII Preliminary ∫Ldt=170/pb

**Band**: correlated error from Energy scale uncertainty

- Cigdem Issever, UCSB

## AW() with 25 < ET < 35 GeV

- CDFII Preliminary ∫Ldt=170/pb

- Cigdem Issever, UCSB

## AW() with 35 < ET < 45 GeV

**A****W****(********) with 35 < E****T**** < 45 GeV**

- CDFII Preliminary ∫Ldt=170/pb

- Cigdem Issever, UCSB

## AW() for different ET ranges

**A****W****(********) for different E****T**** ranges**

- CDFII Preliminary ∫Ldt=170/pb

- Cigdem Issever, UCSB

## Conclusion

- We measured the W Charge Asymmetry
- Provides new PDF constraints

- Joey Huston, CTEQ6.1 (ResBos NLO,NLL)

**Higher Pt prediction indicates that data has more pdf discrimination**

- CDFII Preliminary ∫Ldt=170/pb

- CDFII Preliminary ∫Ldt=170/pb

- Cigdem Issever, UCSB