Now Detector commissioning Calibrations Early physics SUSY/Higgs Preparing for LHC physics in ATLAS Ivo van Vulpen Complex SM

Now

Detector commissioning

Calibrations

Early physics

SUSY/Higgs

Preparing for LHC physicsin ATLAS

Ivo van Vulpen

Complex SM

1 fb–1

100 pb–1

10 pb–1

Integrated luminosity

TimeLHC startup

0 Understand ATLAS Testbeam/cosmics

1 Understand SM+ATLAS in simple topologies

Understand SM+ATLASin complex topologies

2

Look for new physicsin ATLAS at 14 TeV

3

LHC start-up programme

W/Z

Top quark pairs

Higgs/SUSY

Andreas Hoecker

ECAL uniformity 1-2% Ze+e-, minimum biase/γ scale 2% Ze+e-

HCAL uniformity 3% jets, single pionsJet scale <10% γ/Z+jet, Wjj in tt events

Tracking alignment 10-200 μm Rφ tracks, isolated μ, Zμ+μ-

ECAL uniformity 1-2% Ze+e-, minimum biase/γ scale 2% Ze+e-

HCAL uniformity 3% jets, single pionsJet scale <10% γ/Z+jet, Wjj in tt events

Tracking alignment 10-200 μm Rφ tracks, isolated μ, Zμ+μ-

Performance Expected day-1 Physics samples to improve Performance Expected day-1 Physics samples to improve

Expected detector performance from ATLAS (based on testbeam, cosmics-data and simulations)

The ATLAS detector at day-1

First job is to get a combined ATLAS detector operational

ATLAS preliminary, 1 pb-1

J/

Y

Nu

mb

er

of

even

ts

Nu

mb

er

of

even

ts

Mμμ (GeV)

First SM peaks & an early discovery

Mμμ (GeV)

Reconstruction efficiencies, Muon spectrometer alignment,Detector and trigger performance, Tracking momentum scale, ECAL uniformity, E/p scale, …

Events per day at day 1 (L=1031):

4200 (800) J/ (У) +- 160 Z +-


Maaike LimperCaroline MagrathEgge van der Poel

e+e-

+-

Mμμ (GeV)

Early discoveries:

Heavy resonances lepton pairs


J/

Y


Nu

mb

er

of

even

ts

Nu

mb

er

of

even

ts

Mμμ (GeV)

First SM peaks & an early discovery

Mμμ (GeV)

Drell-Yan (SM)

10%

90%

Top quark pair-production: σtt(LHC) ~ 833 ± 100 pb

1 top quark pair per second

Focus on semi-leptonic decays (4/9)

t

t

Top quark physics

Top analyses: SM: Top, single-top non-SM: Mtt, FCNC (tZc), H+/-

Top quark physics

“Top quark pair production has it all”: ≥ 4 jets, b-jets, neutrino, lepton

a) Early cross-section measurement b) Unique calibration opportunities Background to many new physics signals

“Top quark pair production has it all”: ≥ 4 jets, b-jets, neutrino, lepton

a) Early cross-section measurement b) Unique calibration opportunities Background to many new physics signals

Mjjj (GeV)

Commissioning analysis:

- Missing ET > 20 GeV - 1 lepton PT > 20 GeV - 3(4) jets PT > 40(20) GeV

Top = 3-jet combination with highest sum PT

Note: No b-tag information used

100 pb-1 muon analysis

~ 500 events

Martijn GosselinkAlexander Doxiadis

1) Extra/Fake isolated leptonsEstimate rate for arbitrary event-topology (multi-jet QCD)

2) Calibrate ET-miss scale:

MT(W) using constrained fits

3) Extra jets: tt+jets

Low mass Higgs boson: tt+h(bb)

Top quark physics(understanding ATLAS in complex topologies)

Rate/jet Non-prompt Fake

Muon 1.3·10-3 97% 3%

Electron 1.0·10-3 62% 38%

Alexander DoxiadisManuel KaylErik van der Kraaij Manouk RijpstraMartijn Gosselink Menelaos Tsiakiris

Num

ber

of

events

W-boson transverse mass (GeV)

Direct: mh >114.4 GeV at 95% CL

EW-fit+direct: mh< 182 GeV at 95% CL

Direct: mh >114.4 GeV at 95% CL

EW-fit+direct: mh< 182 GeV at 95% CL

The Higgs boson

LEP

dir

ect

searc

h

Higgs decay

Higgs boson mass (GeV)

Hig

gs

bra

nch

ing

fra

ctio

n

ZZ

WW

bb

Gluonstau’sLu

min

osi

ty n

eeded f

or

dis

covery

(fb

-1)

Higgs boson mass (GeV)100 200 300 500 1000

- 5σ discovery

- 95% CL exclusion

ATLAS + CMS

LEP

dir

ect

searc

h- LHC reach (ATLAS+CMS): 5 fb-1 needed for 5σ discovery - mh < 130 GeV: tth(hbb). Difficult.

> 130 GeV: hWW(*) and hZZ(*)

1 fb-1

Note: to prove we see the SM Higgs boson requires (much) more data

Martijn GosselinkManuel Kayl

- In combination with gg hWW- Less statistics, but clear signature 5-dimensional fit… based fully on background control samples

The Higgs boson(vector boson fusion: W+W-hW+W- l+vl-v)

Transverse Higgs boson mass (GeV)

Num

ber

of

events

mh = 170 GeV

-- background signal +

bkg

1 fb-1 data: ~2.5 sigma

Max BaakGijs van den Oord


Sta

t. S

ignifi

cance

[S

D]

•“No-lose” theorem: W-W scattering:No lose approach:

Something should regularize vector boson scattering in SM

W.Z

W.ZW.Z

W.Ztheory + experiment

Supersymmetry

SUSY: - boson/fermion symmetry, SM particles have partners, LSP - broken many models/topologies (GMSB, AMSB, NUHM, mSUGRA)

(WMAP)

m1/2 (GeV)

m0 (

GeV

)

g-2

Mass spectrum

Part

icle

mass (

GeV

) 800

700

600

500

400

300

200

100

0

gluino

Higgs boson(LEP) LSP (ΩDM)

m0 = 100 GeVm1/2 = 250 GeVtan = 10

stau LSP

mSUGRAtan(β)=10

ATLAS 100 pb-1

Supersymmetry(decay chains and event topologies)

l ~

l ~

q ~

q ~

~

01

02

l

q

g

SUSY events look like top events

SUSY events look like top events

0,1,2 leptons

≥4 jets

(a lot of) missing ET

Mass spectrum

Part

icle

mass (

GeV

) 800

700

600

500

400

300

200

100

0

Inclusive search (1 lepton)

ATLAS’ inclusive SUSY searches

Effective mass (GeV)

Nu

mb

er

of

even

ts

ATLAS reach: ~ 1 TeV for 1 fb-1

Note: Much more data required to: - is excess sign of supersymmetry ? - reconstruct (part of) particle spectrum and underlying parameters

SUSYmissT

4

1ijet

iTeff MEpM

Data-driven background estimates(Nikhef’s main contribution to ATLAS SUSY search)

Determine SM background in signal region:

a) Extrapolate three SM backgrounds separately to signal regionb) Account for SUSY signal events in sidebands

ET-miss (GeV) ET-miss (GeV) ET-miss (GeV) ET-miss (GeV)

SUSYSM:W+jetsSM: tt(lvlv)SM: tt(lvqq)

sideband sideband sidebandsideband

MT (G

eV

)

Alex KoutsmanFolkert KoetsveldNicole Ruckstuhl

MT (G

eV

)

MT (G

eV

)

MT (G

eV

)

More exotic scenario’s

• Extra space-dimensions:

- Kaluza-Klein excitations: G(n) ,Z(n)

- Mini black holes

• Z’, ZH, W’, WH

• Little/Twin Higgs

• …

“An experimentalist cannot afford to have a theoretical predjudice”

Calabi-Yau

Great collaboration between experiment and theory ahead

Manouk Rijpstra

WH tbtt

mass (GeV)

Num

ber

of

events

Little Higgs300 fb-1

Summary and outlook

2007:

o ATLAS Detector paper o Update ATLAS analysis potential (CSC Notes, focus on early data)

2008:

o Detector commissioning o Full dress rehearsal Simulate chain with mock data (data transfer, trigger, Grid-analyses)

o Focus on first data: J/ψ, top-cross-section … Higgs, SUSY

Back-up slides

The Higgs boson

Sig

nal si

gnifi

cance


Higgs production


cross

-sect

ion

(pb

)

ΔM/M = 0.1% for 130<mh<450 GeV

ΔΓ/Γ < 10% for mh>300 GeV

Couplings SM-like ? Scalar ?Higgs self-coupling (λ) ~3000 fb-1

Simplest SM extension (MSSM):2 complex Higgs Doublets 5 Higgs bosons (3 neutral)

)(cos

)(sin

)bb(h

bbh2

2

SM

Higgs boson properties:

The Higgs boson(properties and extensions to SM)

Extensions to SM:

MSSM searches:

- Entire MSSM parameter space covered by at least one Higgs boson- Sometimes more Higgs bosons observable [link to SUSY]

MSSM searches:

- Entire MSSM parameter space covered by at least one Higgs boson- Sometimes more Higgs bosons observable [link to SUSY]

)(sin WW)(h

WWh 2

SM

Higgs boson mass (GeV)Pre

cisi

on c

ouplin

g r

ati

o

ATLAS 300 fb-1

Bosons: Γz/ΓW & Γγ/ΓW ~ 10-20%Fermions: Γτ/ΓW & Γb/ΓW ~ 40-50%

Supersymmetry

mSUGRA: (5 parameters)

- A0, sign(μ), tan (β) - m0: universal scalar mass - m½: universal gaugino mass

mSUGRA: (5 parameters)

- A0, sign(μ), tan (β) - m0: universal scalar mass - m½: universal gaugino mass

R-parity is conserved - Stable Lightest Supersymmetric Particle: LSP

R-parity is conserved - Stable Lightest Supersymmetric Particle: LSP

10Log(Energy scale) (GeV)

1016

Evolution of masses

mass (

GeV

)

m0 = 100 GeVm1/2 = 250 GeVtan = 10

Num

ber

of

events

ATLAS mSUGRA reach

Supersymmetry(exclusive searches)

1) Exclusive search (end-point spectra)

ATLAS 300 fb-1

2~

2~

2~

2~

~max

01

02

02

11R

R

l

χ

χ

l

χll m

m

m

mmm

cleaned SUSY signal

Standard model

Di-lepton mass (GeV)

Num

ber

of

events

Documents

Now Detector commissioning Calibrations Early physics SUSY/Higgs Preparing for LHC physics in ATLAS Ivo van Vulpen Complex SM