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Ivo van Vulpen

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2) Even if we do: hierarchy problem, or 'Why is MEW ' MPL ? ... Conspiracy' to get mh ~ MEW (' MPL) Biggest troublemaker is the top quark! predicted observed ... – PowerPoint PPT presentation

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Title: Ivo van Vulpen


1
Looking beyond the horizon using top quark
physics at the LHC
Ivo van Vulpen
2
Layout talk
1) Motivation the SM and beyond
2) Roadmap to discovery ? SM Top quark
physics at vs 14 TeV ?Beyond Anomalies in
top quark events
VIDI proposal
3) Workplan
3
The Standard Model the Higgs boson
  • The Standard Model - Combines the EM, weak and
    strong force - Describes all measurements down
    to distances of 10-19 m
  • Electro-Weak Symmetry Breaking (Higgs
    mechanism)- Weak gauge bosons and particles have
    mass- Regulate WW/ZZ scattering

4
All measurements in HEP can be explained using
the SM
The Higgs boson will be discovered at the LHC at
150 GeV
NO !
Many open questions in SM. but also things we
do not understand Gravity, Cold Dark Matter,
Why 3 families, Why mt me m? Higgs
1) Higgs has not been discovered 2) Even if we
do hierarchy problem, or Why is MEW MPL ?
5
The hierarchy problem
  • Success of radiative corr. in the SM

predicted observed
?
Hierarchy problem ? Conspiracy to get mh
MEW ( MPL) ? Biggest troublemaker is the top
quark!
6
Solutions to the hierarchy problem
Extra Dimensions
Little Higgs
Higgsless
SUSY
Standard Model
?
mSUGRA
GMSB
AMSB
7
Main idea / approach
  • Idea 1 Do not concentrate on a specific model
    (model 1,2, ) Look for
    fingerprint of new physics in specific topology

SM
model 1
model 2
model 3
Data
model 4
model 5
model 6
8
The ATLAS detector at the LHC
Process events events
sec-1 10 fb-1
The LHC collider
T - 500 days
Luminosity per year 2007 100 pb-1
Nominal 10 fb-1
The ATLAS detector
First year Enormous reach for new physics.
Need to understand detector and
SM at vs 14 TeV.
9
Top physics at the LHC
  • Top production at the LHC

85
7.5 million events/year
NLO Monte Carlo
2) Measure top properties Charge, couplings,
mass, cross section, . 3) Use tt events as a
calibration tool Complex topology with
multiple constraints
10
Top physics at the LHC
Top quark pair production has it all
4 jets, b-jets, neutrino, lepton several
mass constraints for calibration
Note the 4 candles - 2 W-bosons Mw 80.4
GeV- 2 top quarks Mt Mt-bar
11
LHC day 1 See the top
  • Standard-analysis 2 b-jets ? S/B 80
  • Commissioning-analysis no b-tag (robust cuts)

Hadronic 3-jet mass
ATLAS
Events / 4.15 GeV
L100 pb-1
mtop
Mjjj (GeV)
12
LHC day 2 Resonances ?
  • Structure in Mtt
  • Resonances in Mtt

Interference from MSSM HiggsesH,A? tt (6-7
effect)
Resonance of 1600 GeV
?s/s 6
events
Cross section (a.u.)
Mtt (GeV)
Mtt (GeV)
13
LHC day 2 First to discover SUSY
In R-parity conserving models the LSP is stable
and escapes detection (mSUGRA)
Topology 4 jets missing ET
(large) leptons/photons
SUSY events are in top sample!
14
Plan of research
Commissioning analysis 4 jetslepton missing ET
Investigate leptonic side
InvestigateHadronic-side
  • Improve lepton identif. and trigger in
    multi-jet events
  • Calibrate missing ET
  • Reconstruct total tt-system. Measure
    differential cross section.
  • Calibrate Jet energy scale
  • Select clean b-jet sample

Develop constrainedfittingpackage
Extra leptons in tt-like events SUSY
Resonances in
15
Rediscover the topconfidence!
1) Prepare for first data - Calibration
strategy trigger - Constrained fitting
- Weltmeister!
2) SM Top physics - Cross section
(leptons) - Jet energy scale
3) Beyond the SM - Structure in Mtt -
SUSY with leptons - ?
BONUS
Possibility to divert interest quickly if anomaly
appears in unexpected topology
16
Summary
Base scenario
Top physics Important scientific program!
Great scenario
Hint of new physics elsewhere extra information
from top sector
Perfect scenario
New physics strong in top sector ? discovery!
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