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