Transcript Neutrino-Nucleon sin2theta_W-part 2

PHYS 5326 – Lecture #8
Monday, Feb. 17, 2003
Dr. Jae Yu
1. Interpretation of Sin2qW results
2. The link to Higgs
Move Wednesday’s class and the makeup class to
Friday 9am-12pm in rm 200, this week only!!
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
1
Last Week’s Homework Assignments
• Process the transferred TMB data files and
convert them into TMBtree for root analysis
– You can work together on this one
– One person can produce TMBtree for all
– Due next Monday, Feb. 17
• Produce an electron ET spectrum of the highest
ET electrons in your samples
– Due next Wednesday, Feb. 19
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
2
MC to Relate Rnexp to Rn and sin2qW
• Parton Distribution Model
– Correct for details of PDF model  Used CCFR data for PDF
– Model cross over from short nm CC events
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
3
MC to Relate Rnexp to Rn and sin2qW
• Neutrino Fluxes
 nm,ne,`nm,`ne in the two
running modes
 ne CC events always look
short
• Shower length modeling
– Correct for short events that
look long
• Detector response vs
energy, position, and time
– Continuous testbeam
running minimizes
systematics
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
4
sin2qW Fit to Rnexp and R`nexp
• Thanks to the separate beam  Measure Rn’s separately
• Use MC to simultaneously fit Rnexp and Rnexp to sin2qW and
mc, and sin2qW and r
Rn (n ) 
σnNC(n )
σnCC(n )
n (n )  


σ
1
5
 ρ 2   sin2 θ W  sin4 θ W  1  nCC(n )  
2

9
σ
CC  


• Rn Sensitive to sin2qW while R`n isn’t
Rn is used to extract sin2qW and R`n to control systematics
Why???
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
5
sin2qW Fit to Rnexp and R`nexp
• Single parameter fit, using SM values for EW parameters
(r0=1)
sin θ W  0.2277  0.0013 (stat)  0.0009 (syst)
2
m c  1.32  0.09 (stat)  0.06 (syst) w/ m
2
c
 1.38  0.14 GeV/c as input
•Two parameter fit for sin2qW and r0 yields
sin θ W  0.2265  0.0031
2
ρ 0  0.9983  0.040
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
Syst. Error dominated
since we cannot take
advantage of sea quark
cancellation
6
NuTeV sin2qW Uncertainties
Dominant
uncertainty
d sin2qW
Source of Uncertainty
Statistical
0.00135
ne flux
0.00039
Event Length
0.00046
Energy Measurements
0.00018
Total Experimental Systematics
0.00063
CC Charm production, sea quarks
0.00047
Higher Twist
0.00014
Non-isoscalar target
0.00005
n /n
0.00022
RadiativeCorrection
0.00011
RL
0.00032
Total Physics Model Systmatics
0.00064
Total Systematic Uncertainty
0.00162
DMW (GeV/c2)
Monday, Feb. 17, 2003
1-Loop Electroweak Radiative
Corrections based on Bardin,
Dokuchaeva JINR-E2-86-2 60 (1986)
2 (On  shell)
W
δsin θ
0.08
PHYS 5326, Spring 2003
Jae Yu
 M 2t  175GeV 2 

 0.00022  
2

 50GeV 

 MH 
 0.00032  ln

150GeV


Mhiggs
Term
Mt
Term
7
NuTeV vs CCFR Uncertainty Comparisons
}Beamline worked!
}Technique worked!
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
8
Comparison of New sin2qW
 Shell
sin2 θ On
 0.2277  0.0013 (stat)  0.0009 (syst)
W
2
sin θ
 MW
On Shell
On shell
W
M 2W
 1 2
MZ
 80.14  0.08 GeV/c 2
Comparable precision but value smaller than other measurements
2.5 
deviation!
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
9
SM Global Fits with New Results
Without NuTeV
c2/dof=20.5/14: P=11.4%
With NuTeV
c2/dof=29.7/15: P=1.3%
Confidence level in upper
Mhiggs limit weakens slightly.
LEP EWWG: http://www.cern.ch/LEPEWWG
Monday, Feb. 17, 2003
PHYS 5326, Spring 2003
Jae Yu
10