Transcript The top quark

Top quarks and
physics at 100 zeptometer
Ivo van Vulpen
Particle physics
Study nature at distance scales < 10-15 m
10-15 m
atom
nucleus
A quantum theory describes all measurements down to 10-18 m
2/10
Building blocks of
proton/neutron
Particles
Forces
1) Electromagnetism
Quarks
2) Weak nuclear force
Leptons
electron
3) Strong nuclear force
neutrino’s
3/10
The big questions:
What is dark matter made of ?
Why is gravity so different ?
What explains the required (extreme) tuning of parameters ?
4/10

Model is an ‘approximation’ of
a more fundamental one.

Model breaks down below 10-19 m
Extra dimensions ?
New phenomena will appear
at distances ~ 10-19 m
2006
Super-Symmetry ?
String theory ?
Edward Witten’s
latest insight ?
5/10
The LHC collider: ‘proton-microscope’
- proton-proton
- high energy / intensity
- start summer 2007
ATLAS detector
LHC tunnel
6/10
What will LHC events look like?
Problem: new distance scale and new detector
“Before claiming you have observed something ‘new’
you need to understand what ‘old physics’ looks like”
Most complex ‘old physics’: top quark pairs
quark
Simulated top quark pair in detector
quark
quark
proton
electron
proton
neutrino
quark
1 event/s
7/10
Why look at top quarks ?
• The top quark
- Discovered in 1994
(few 100 events)
- Mass ~175 x proton mass
• My current research:
Number of events
‘Old’ physics, but not ‘known physics’!
Expected top quark mass
distribution (end of 2007)
At LHC top quarks copiously
produced (high energy)
- We can identify top quarks
in early LHC data
Mass of top quark (GeV)
8/10
100 zeptometer frontier: discover ‘new’ physics
• What do new phenomena look like ?
New ?
- Depends strongly on theoretical model
?
- Many models include a signature that looks
a lot like top quarks, but not quite …
• My strategy:
Focus on this single signature rather than
on a single theoretical model
Top quarks
- Single source of known physics that can
mimic this is top quark production
(which we understand !)
9/10
Why am I doing this ?
Data-Analysis
(search + measurement)
PhD thesis
Research group
VIDI !
1)
2)
3)
4)
Leptons: Identification and Trigger
Quarks: Jet energy scale and top cross section
Kinematic fit
Top characteristics and Model interpretation
Detector
commissioning
CERN fellow
Top quark physics
in ATLAS
NIKHEF post-doc
10/10
Time-line
Phase 1:
Prepare and study
first LHC collisions
Phase 2:
Re-discover top quark
2008
2007
2006
2009
Plan of work
2010
2011
2012
Phase 3:
First to observe and study
new phenomena
Discover super-symmetry ?
Discover extra dimensions ?