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 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 BDT>220 W + W -   +  BDT>290 W + W -  e +  - 406± ± BDT >220 W + W -  l + l ± ±2.0 25Straight cuts W Z  l l + l ± ±2.5 38BDT > ± ±1.2 20Straight cuts ZZ  4 l 11.0± ± Straight cuts ZZ  l + l ± ± Straight 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 e-4 0.9e e-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