Prsentation PowerPoint

1
From the ATLAS EM Calorimeter to Supersymmetry
Universität Bonn 12/07/2007 Dirk Zerwas LAL Orsay

• Introduction
• ATLAS EM-LARG
• Electrons and Photons
• Supersymmetry
• Reconstruction of fundamental Parameters
• Summary

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Introduction

• The standard model
• Matter quarks and leptons (Fermions)
• forces mediated by bosons
• Masses via Higgs mechanism

Strong interaction g Electromagnetic
interaction Photon weak interaction W, Z

• Search for the Higgs boson
• LEP (ee-) MH gt114GeV
• electroweak obs top mass, W mass
• radiative corrections depend on MH
• MH lt153GeV

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LHC

• Proton-Proton collisions
• Center of mass energy
• 2008 14 TeV
• BX 40.08MHz
• Low luminosity
• 10fb-1 per experiment (3 years)
• High luminosity
  10x low (N years)
• SLHC
• 10x high (2015 and later)

2 multi-purpose detectors ATLAS, CMS

• Experimental challenges at the LHC
• bunch crossing every 25ns
• 22 events pro BX (quick selection/readout, 40MHz
  ? 200Hz, 1.6MB per event)
• High radiation ?FE electronics difficult (space
  technology)
• with all that precision physics!

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45 of nominal I
25 of nominal I
L1032cm-2s-1 1fb-1 p.a. end 2008 ?
43/156 Bunches
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The ATLAS Detector
Detection and Measurement of electrons and
photons energy and direction
Definition ? -ln tan?/2 ? polar angle ? 900
? 0

• Track reconstruction (?lt2.5, B2T)
• Si Pixels and Strips (12 precision points)
• Detector for transition Radiation (TRT 40points)
  
• Calorimeter (?lt5)
• EM Lead-LiquidArgon
• HAD Fe/Scintillator (central), Cu-W-Lar (fwd)
• Myonchambers (?lt2.7)
• Luftcore toroids with muon chambers

Jörn Grosse-Knetter Christoph Rembser
Length 45m Radius 12m Weight
7000Tonnen Channels 108 3000km cable
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Higgs Boson decay to two photons requirements on
the calorimeter

• Higgs Bosons at the LHC
• short lifetime ? immediate decay
• Example MH120GeV, Higgs ? ??
• calorimeter!

H ?WW()
H ?ZZ()
1000000 Higgs Bosons 2000 Higgs??? 1013
Jets 150x106 W ? e? 15x106 Z ? ee
H ???
Cross section, Branching ratios Photon-ID, Jets
Mass Energy resolution Energy scale (Direction)
measured by the calorimeter
Djouadi
MH
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The electromagnetic Calorimeter of ATLAS

• Characteristics
• passive Lead(St.St.) absorber (1.1mm)
• active LiquidArgon 2.2mm (cryostat 90K)
• Accordion structurr ? no dead regions in f
• easy to calibrate

granularity (?? X ?f) presampler 0.025x0.1 (up
to ?1.8) strips 0.003x0.1 middle
0.025x0.025 Back 0.05
x0.025
FE electronics Z3.2m, R2m
f
R 2m
R 1.4m
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Signal and Elektronics
GLINK
SCA Analog pipeline 16 channels 2µs (Trigger
LVL1) Delagnes/Breton Digitalosziloskop (Metrix,
CAEN)
LV
TID 170kRad NIEL 2x1013 n/cm2 SEE 8x1012 h/cm2
450ns -gt 50ns (bipolar) (BX 25ns)
Detector
FEB 128 channels functional prototype 1998 Test
beam 1998-2002 (40 boards) Rad tol (DMILL,
DSM) ATLAS 1527 FEB Production 1year/2
hours/board 50 repairs 10 expected ? and its
not finished yet..
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Reconstruction of electrons and photons

• calibration of elektronics
• cluster of about 50 cells
• energy position corrections
• global 0.7
• local (??X?f0.2x0.4) lt 0.5
• corrections inspired and tested
• ATLAS simulation
• test beam data 1998-2002
• 6 ATLAS EM modules (15)

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Energy scale
Between PS and calo
in front of PS
Longitudinal leakage
Simultaneous optimisation of energy resolution
AND Linearity
s/E 10/?E ? 0.2
Linearity test beam 0.1 (20-180 GeV) ATLAS
simulation ok up to 1TeV
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Uniformity and Z?ee

• uniformity 0.2x0.4 ok in test beam
• energyscale 0.13
• Good agreement Data/MonteCarlo

Module P13
245.6 GeV
0,44

• Z?ee Monte Carlo and Data in ATLAS for
  intercalibration of 448 regions
• Z Masse (well) known
• Eireco Eitrue(1ai)
• Mijreco Mijtrue(1(aiaj)/2)
• fit to a reference distribution
• Low luminosity
• 0.3 intercalibration 1week! Global constant Term
  0.7 is achievable!

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Electron and Photon Identification
Dijet cross section 1mb Z ? ee 1.5 10-6
mb W ? e? 1.5 10-5 mb electrons and
photons shower shape in calorimeter against jet
background
Shower width 40 Strips
electrons calorimeter and track reconstruction
e.g. Pixel detector April 5, 2007 Jörn
Grosse-Knetter
Cuts electron (photon) efficiency 75-80
background rejection 105 (7000) multivariate
analyses (neuronal nets, loglikelihood, boosted
decision tree etc)
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e/p separation using the TRT
5.5 keV
TR threshold electron/pion separation
0.2 keV
MIP threshold precise tracking/drift time
determination
CTB 2004 _at_low energy 2-9GeV
Bd0?J/? Ks0
May 10, 2007 Christoph Rembser
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?/p0 separation

• need a separation factor of at least 3
• use finely segmented first CALO compartment and
  search for secondary minima,
• shower width etc

E2nd max - Emin
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Position/Angular measurements
? mid
550 µm at ?0
245 GeV Electrons
? strip
?
250 µm at ?0
sZ20mm
H? ?? vertex reconstructed with a precision of
2-3 cm in ATLAS in z Precision of theta
measurement 50mrad/?E
sZ5mm
Good agreement of Monte Carlo and Data!
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Higgs-Boson Reconstruction
Energy resolution
nat. width
Higgs
10/?E ? 0.7 ? 0.004GeV/E
uniformity
1.5 ? 7x10-7 The smaller s more signal, less
background
irreducible

• Background
• irreducible 0.125pb/GeV
• reducible 0.03pb/GeV
• OK

H ? ZZ ? 4e MH129.7GeV (130GeV) energyscale
OK
ATLAS preliminary
H??? MH119.8GeV (120GeV) energyscale OK
ATLAS preliminary
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Supersymmetry

• fermion ?boson
• has no problems with radiative corrections
  (quadrat. div.)
• has a light Higgs Boson (lt150GeV)
• interesting pheno at the TeV scale

3 neutral Higgs bosons h, A, H 1 charged Higgs
boson H and supersymmetric particles

• Many different models
• MSSM (minimal supersymmetric extension of the
  standard model)
• mSUGRA (minimal supergravity)
• GMSB
• AMB
• NMSSM

• R-Parity
• Production of SUSY particles in pairs
• (Cascade-) decays to the lightest SUSY particle
• LSP stable, neutral and weakly interacting
  neutralino (?1)
• experimental signature missing ET

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Supersymmetry
Unification of the coupling constants
Allanach et al
Supersymmetry breaking
mSUGRA 5 parameters GUT scale
MSSM 24 parameters EW scale
GUT 1016GeV
EW-scale 102GeV

• Status of the search for supersymmetry
• LEP
• sleptons gt95GeV
• charginosgt104GeV
• neutralino1 (LSP) gt45GeV
• TeVatron
• squarks, gluinos gt 300/400GeV

April 19 2007 Marc Hohlfeld
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SPS1a
m0 100GeV m1/2 250GeV A0 -100GeV
tanß 10 sign(µ) good for LHC and ILC!
gluinos and squarks (not too heavy)
Physics Interplay of the LHC and ILC G.
Weiglein et al
heavy and light gauginos

• t1 lighter than the lightest ?
• ? BR 100 t?
• ?2 BR 90 tt
• cascade
• qL ? ?2 q ? lR l q ? l l q?1

Higgs boson mass at the LEP limit
light sleptons
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Edges and Masses
S. Asai
Xsection for squarks and gluinos pb sum jet-PT
and ET ?effective mass
hard jets with leptons Invariant mass Jet-Lepton,
Lepton-Lepton-Jet, Lepton-Lepton
SUSY
SM

LHC Leptonen 0.1 LHC Jets 1

• Linear collider
• ee- collisions
• up to 1TeV
• decision around 2010

June 2007 Jochen Kaminski, Michael Hauschild
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Determination of Supersymmetric Parameters
In the Lions den LionsKlausPeter
from edges, masses (etc) to fundamental
parameters e.g. mSUGRA M(Smyon) f(m0, m1/2,
tanß) M(Chargino) f(m1/2, tanß,) ? global
Ansatz necessary
Beenakker et al

• mass spectra SOFTSUSY, SUSPECT, ISASUSY
• 2-loop RGEs, radiative corrections to particle
  masses
• Branching ratios Sdecay
• 2, 3, 4 body decays (transition 2-3), QCD
  corrections and electroweak corrections, 1-loop
  SUSY-QCD
• NLO cross sections from Prospino2.0
• MICROMEGAS

Error calculation, search for minima with GRID
(both senses of the term) Markov chains
etc FITTINO P. Bechtle, K. Desch, P. Wienemann
with W. Porod SFITTER R. Lafaye, T. Plehn, M.
Rauch, D. Z. (GDR SUSY, Les Houches 2003)
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Lagrangian_at_GUT scale mSUGRA
1TeV (100GeV)

• find the right parameter set?
• with which precision?

1TeV (250GeV)

• errors LHC
• errors ILC 0.1
• LHCILC small improvement
• mTop important
• even more important
• theory errors!

50 (10)
0GeV (-100GeV)
sign(µ) fest
300 toy experiments convergence OK!
Important contribution of the SPA project
precision of the theoretical calculations
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MSSM

ILCLHC

ILC
LHC
24 parameters at the EW scale no unification of
the 1st and 2nd generation

• LHC or ILC alone
• parameters fixed
• LHCILC
• all parameters determined
• several parameters improved

Running up to the GUT scale SFitterJ.L. Kneur
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Connection LHC-Cosmology

• The Universe
• dark energy 73
• atoms 4
• cold dark matter (CDM) 23

NASA/WMAP science team

• LSP
• massive
• weakly interacting
• SPS1a ?1 ideal candidate for CDM

• SUSY breaking parameters (determined)
• Spectrum and couplings (deduced)
• micrOMEGAs (Bélanger et al.) OCDMh2nLSPmLSP
  (relic density)

Temperature range 200µK

• Measurement of the fluctuations of the cosmic
  microwave background
• WMAP
• OCDMh20.1270.01 (astro-ph/0603449)
• Planck
• OCDMh2 2

• LHC Oh2 0.1906?0.0033
• LHCILC Oh2 0.1910?0.0003
• improvement by an order of magnitude (theory
  errors!)

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Summary

• EM Calo and Electronics ready

• Electrons and Photons can be identified

ATLAS preliminary

• with LHC,ILC, Supersymmetry and SFitter (and
  Fittino we will go to the GUT scale!

• and are well calibrated