Current SM studies
CMB
Reports at last meeting
• W/Z cross-section (CSC)
• W-mass (CSC)
• Dibosons (CSC)
• Minimum bias (CSC)
• W+charm
W/Z cross-section
Around 18 people?Covering• Electron and muon trigger
efficiency• Muon trigger efficiency• Particle ID and
reconstruction for electrons and muons
• Missing Et• Event selection with 1pb-1
and 1fb-1
• Cross-sections for Zee,,lldN/dy, dN/dpt
muons
electrons
Earlyresults
Di-bosons
• 10 institutesDiboson mode Signal Background S/√B Analysis
W e 3780±61 1186±34 110 BDT (ε=50%)
W 5864±77 1752±42 140 BDT (ε=50%)
Z e+e- 289±17 160±13 23 BDT (ε=60%)
Z +- 650±25 343±19 35 BDT (ε=60%)
W+W- e+e- 72.6 36.2 12 BDT>220
W+W- +- 90.0 20.1 20 BDT>290
W+W- e+- 406±3.4 103±18.5 40 BDT >220
W+W- l+l- 103.1±2.6 16.6±2.0 25 Straight cuts
W Z l l+l- 152.6±1.7 16.1±2.5 38 BDT >200
53.4±1.6 6.7±1.2 20 Straight cuts
ZZ 4l 11.0±0.1 2.2±0.1 7.6 Straight cuts
ZZ l+l- 10.2±0.2 5.2±2.0 4.5 Straight cuts
~10 institutes
Lepton Trigger Efficiency
mu20i : isolated muon PT>20 GeVe25i : isolated electron ET>25 GeV
Evaluated with Z decay leptons Single particle loses to geometrical gap, multiple particles reaches 100%
Lepton Reconstruction Efficiency
Leptons of W, Z decayReconstruction efficiency of
o IsEM 0x7FF with a track matchingMuID
PT distributions η distributions
9Summary
Physicists from ten institutes contributed to Di-Boson Physics CSC note. First draft is ready.
Analysis tools, such as BDT, are developed and tested in our studies.
With fully simulated MC events (both signal and background) we show that ATLAS will establish the WW, WZ, Wγ and Zγ signals with significance better than 5 with the first 100 pb-1 data. ZZ signal will be established with the first 1 fb-1 integrated luminosity.
Cross-section measurements, with 5-10 fb-1 integrated luminosity, the systematic errors will be the dominant uncertaintites.
Charged TGC sensitivity will be significantly improved with 100 pb-1 data to the Tevatron limits; and with 30 fb-1 data it is orders of magnitude improvement to LEP/Tevatron.
Neutral TGC sensitivity will be much tight compared to the limit from LEP and Tevatron for 1 fb-1 data.
Z-asymmetry
• Small number of people
• Looking at forward electron reconstruction
M. Aharrouche page 11SM meeting
Method Multivariate analysis Inputs variables
Topo cluster moments
+other variables Optimal set of variables
Iterative method Discriminante analysis
Distinguish two eta bins : EMEC (2,5<||<3,2) and FCal (3,2<||<4,9 )
Signal and background: Full sim. (CSC) Electrons from Z->ee Jets QCD
M. Aharrouche page 12SM meeting
Variables
Fraction of the energy in the
most energetic cell
Moment of order 2 M(di ) of the
distance di of each cluster cell i to the
shower center
Ma(di)/ [Ma(di)+Mb(di)]
Condition a: distance of the two most
energetic cells = 0Condition b: distance
of the two most
energetic cells = 10cm and the distance of the
other cells = 0
EMEC FCal
signalbkg.
CELLMAXFRACCELLMAXFRAC
SECONDLAMBDANSECONDLAMBDAN
LONGITUDINALLONGITUDINAL
M. Aharrouche page 13SM meeting
Iterative Method
EMEC FCal
Principle: At each step i, the combination of i (in N-i)
variables leading to the good efficiency for a given rejection is choosen, and the i-1 variables from the step i-1 are kept.
Step 1: energy fraction in the most energetic cell
Step 2: + variable 3 Step 3: + variable 5 ...
M. Aharrouche page 14SM meeting
Discriminant analysis
likelihood
signalbkgd
EMEC FCal
Results
M. Aharrouche page 15SM meeting
2.4 1.4e-4 0.9e-4
1.13 2e-4 2.6e-4
Others
• W-mass– Focus detailed systematics– Energy/momentum scale and linearity– Pt(W) for pt(l)– Efficiency– Get to Mw~6GeV with 10fb-1
• Min bias – known