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 Z ee, ,ll dN/dy, dN/dpt muons electrons Early results
Di-bosons 10 institutes Diboson modeSignalBackgroundS/√BAnalysis W e 3780±611186±34110 BDT ( ε=50%) W 5864±771752±42140 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 12BDT>220 W + W - + - 90.0 20.1 20BDT>290 W + W - e + - 406±3.4 103±18.5 40BDT >220 W + W - l + l - 103.1±2.6 16.6±2.0 25Straight cuts W Z l l + l - 152.6±1.7 16.1±2.5 38BDT >200 53.4±1.6 6.7±1.2 20Straight cuts ZZ 4 l 11.0±0.1 2.2±0.1 7.6Straight cuts ZZ l + l - 10.2±0.2 5.2±2.0 4.5Straight cuts ~10 institutes
Lepton Trigger Efficiency mu20i : isolated muon P T >20 GeV e25i : isolated electron E T >25 GeV Evaluated with Z decay leptons Single particle loses to geometrical gap, multiple particles reaches 100%
Lepton Reconstruction Efficiency Leptons of W, Z decay Reconstruction efficiency of oIsEM 0x7FF with a track matching MuID P T distributions η distributions
9 Summary 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 11 SM 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 12 SM meeting Variables Fraction of the energy in the most energetic cell Moment of order 2 M(d i ) of the distance d i of each cluster cell i to the shower center M a (d i )/ [M a (d i )+M b (d i )] Condition a: distance of the two most energetic cells = 0 Condition b: distance of the two most energetic cells = 10cm and the distance of the other cells = 0 EMEC FCal signal bkg. CELLMAXFRAC SECONDLAMBDAN LONGITUDINAL
M. Aharrouche page 13 SM 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 14 SM meeting Discriminant analysis likelihood signalbkgd EMEC FCal
Results M. Aharrouche page 15 SM 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