1. Trang Hoang Florida State University - Dzero
A measurement of Charge Asymmetry in W→ decay using Dzero detector at FermiLab
Trang Hoang
Florida State University - Dzero
11/11/2018
E06 Meeting - Saskatoon

2. Outline Motivation Wmunu Asymmetry Tevatron – Dzero detector
My first steps
11/11/2018
E06 Meeting - Saskatoon

3. Motivation
A measurement of W+/- boson rapidity (yW) distributions can give a useful information about the Parton Distribution Functions (PDFs) of the u and d quarks in the proton
Contribute to decrease the systematic uncertainties in the measured mass of W boson and Top quark
A test of Standard Model
11/11/2018
E06 Meeting - Saskatoon

4. W Production Asymmetry
W production process
85% cross section of W production comes from the valence-valence and valence-sea interactions
11/11/2018
E06 Meeting - Saskatoon

5. W Asymmetry
W+ boson is boosted along proton’s direction and W- is boosted along anti-proton’s direction because u valence quarks carry more proton’s momentum than d valence quarks
W Asymmetry:
Missing energy can’t be measured in the z direction, therefore W boson is reconstructed with some certain assumptions
The Asymmetry can be extracted from that of the lepton in the decay of W boson .
11/11/2018
E06 Meeting - Saskatoon

6. W→ Charge Asymmetry
The muon charge asymmetry is the composition of the W asymmetry and the asymmetry from the (V-A) decay.
with (y) is muon identification efficiency for positive/negative muons in a rapidity bin y
Luminosity L is charge independent .
In the relativistic limit, y is the same as pseudo-rapidity
y   = - ln[tan(/2)]
11/11/2018
E06 Meeting - Saskatoon

7. Backgrounds Z →  W → ,  →  Z → , one  →  QCD 11/11/2018
E06 Meeting - Saskatoon

8. Current result at Dzero done by Sinjini Sengupta and Sunsan Blessing, FSU
√s = 1.6 TeV, || < 2.0, < x < 0.3,
11/11/2018
E06 Meeting - Saskatoon

9. √s = 1.98 TeV, peak Luminosity  8.5 1031 cm-1 s-1
Tevatron in RunIIb
√s = 1.98 TeV, peak Luminosity  cm-1 s-1
11/11/2018
E06 Meeting - Saskatoon

10. Dzero detector Central tracking system:
Silicon microstrip tracker (SMT)
Central fiber tracker (CFT)
Calorimeter:
Central section
Two end caps
Muon detector: Three layers of scintillators and drift tubes
One layer inside 1.8T magnet
Two layers outside the magnet
11/11/2018
E06 Meeting - Saskatoon

11. My First Steps
11/11/2018
E06 Meeting - Saskatoon

12. Event Selection
SAM data set: muon inclusive events taken before May 1, 2007 in RunIIb
Muon Selection good single muon criteria
Kinematical cuts:
Muon pT > 20.0 GeV
MET > 20 GeV
W Transverse Mass > 40.0 GeV
11/11/2018
E06 Meeting - Saskatoon

13. MET of Wmunu Candidates
11/11/2018
E06 Meeting - Saskatoon

14. Muon pT Distribution, Wmunu Candidates
11/11/2018
E06 Meeting - Saskatoon

15. W Transverse Mass
11/11/2018
E06 Meeting - Saskatoon

16. W pT Distribution
11/11/2018
E06 Meeting - Saskatoon

17. Muon Eta Distribution
11/11/2018
E06 Meeting - Saskatoon

18. Muon Charge Asymmetry, |eta| < 1.6
11/11/2018
E06 Meeting - Saskatoon

19. Things to Do Study trigger efficiencies
Study charge misidentification of the tracking system
Estimate background by MC …
11/11/2018
E06 Meeting - Saskatoon

20. Thanks for your attention !
11/11/2018
E06 Meeting - Saskatoon