frontiers of particle physics iischwanen/fpp2_top1.pdf · 2016-11-24 · 2nd term 2012 frontiers of...
TRANSCRIPT
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 1
Christian SchwanenbergerChristian SchwanenbergerTel.: +44 161 306-6466Tel.: +44 161 306-6466 +1 630 840-6565+1 630 840-6565
[email protected]@cern.ch .ch
22ndnd term 2012 term 2012
Frontiers of Particle Physics IIFrontiers of Particle Physics IITop Quark Physics (1)Top Quark Physics (1)
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 2
ContentContent
1.1. Introduction Introduction
2.2. History of the Top Quark History of the Top Quark
3.3. The Top Quark Today The Top Quark Today
4.4. Top Quark Pair Production Cross Section Top Quark Pair Production Cross Section (ATLAS)(ATLAS)
5.5. Top-antitop Spin Correlation Top-antitop Spin Correlation (ATLAS)(ATLAS)
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 3
1.1. Introduction Introduction
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 4
Objective of Elementary Particle PhysicsObjective of Elementary Particle Physics
“So that I may perceive whatever holds the world together in its inmost folds.”
Goethe, Faust
from the smallest dimensions in microcosm from the smallest dimensions in microcosm to the largest dimensions in the universeto the largest dimensions in the universe
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 4
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 5
Big Bang in the Lab?Big Bang in the Lab?
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 5
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 6
The Tevatron at FERMILAB: pp CollisionsThe Tevatron at FERMILAB: pp Collisions
Main In jec t or & Recyc ler
Tevat ron
Boost er
p p
p sourc e
Chic ago
_
_
CDF DØ
6 0 km6 0 km
p
√s =1.96 TeV ∆t = 396 ns
Run I 1987 (92)-95Run I 1987 (92)-95Run II 2001-11: 100x larger dataset Run II 2001-11: 100x larger dataset at increased energyat increased energy
p _
__1010-12-12s after big bang!s after big bang!
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 6
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 7
The Large Hadron Collider (LHC)The Large Hadron Collider (LHC)
ATLASATLAS
CMSCMS
The Large Hadron Collider: proton-proton collider high energy: √s = 7 TeV soon: √s = 8 TeV 2014-2030??: √s = 14 TeV
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 7
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 8
The Standard Model of Particle PhysicsThe Standard Model of Particle Physics
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 8
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 9
Fundamental InteractionsFundamental Interactions
pp
nn
nn
p
ppp
p
n
nnp
pnp n
p
Abst oßend Anziehend
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 9
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 10
Mass (GeV)Mass (GeV)protonproton
leptonsleptons
quarksquarks
neutrino masses neutrino masses ≪≪ 1 eV 1 eV
Particle MassesParticle Masses
(1976)
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 10
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 11
What is a Cross Section?What is a Cross Section?
diferential cross section: ddiferential cross section: dσ/dΩ:σ/dΩ: - - probability of a scattered particle in a given quantum probability of a scattered particle in a given quantum state per solid angle dΩ state per solid angle dΩ - e.g. Rutherford scattering - e.g. Rutherford scattering experimentexperiment
integrated cross section: σ= ∫ integrated cross section: σ= ∫ ddσ/dΩ dΩσ/dΩ dΩ
Geiger and Rutherford in Manchester
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 11
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 12
Quark Flavours and ColourQuark Flavours and Colour
R=ee−hadrons
ee−−=3∑ quarkcharge2
12
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 13
Hadron ProductionHadron ProductionHadron ProductionHadron Production
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 14
Quark Flavours and ColourQuark Flavours and Colour
R= ee− hadrons ee−−
=3∑ quarkcharge2
12
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 15
Mass (GeV)Mass (GeV)protonproton
leptonsleptons
quarksquarks
neutrino masses neutrino masses ≪≪ 1 eV 1 eV
Particle MassesParticle Masses
(1976)
?
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 15
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 16
2.2. History of the History of theTop QuarkTop Quark
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 17
Historic Top Quark SearchHistoric Top Quark Search
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 18
1984/85: Tevatron collider commissioned and dedicated
October 1985: First collisions recorded by CDFDØ: still in construction
1987: CDF Run-0●
1992: First collisions by DØ
Run I (1.8 TeV): 1992-19961995: Discovery of the top quark!In total ~120pb-1 per experimentDØ: more focused on calorimetryCDF: more focused on tracking
Brief History of the Top QuarkBrief History of the Top Quark
DØ in 1985
Run I Tevatron
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 18
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 19
Cross Section in Hadron Hadron ScatteringCross Section in Hadron Hadron Scattering
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 19
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 20
Top Quark Pair ProductionTop Quark Pair Production
tt gg
qq--
85%85%
qq tt
tt--
tt-- tt-- tt--
gg gg
gg gg gg
tt tt
15%15%
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 21
Top Pair SignaturesTop Pair Signatures
all jetall jet46%46%
dilepton (e/dilepton (e/μ)μ) 6%6%
top decay:top decay:
tt
bb
qq ν,ν,
e/e/μ μ + jet+ jet34%34%
~100%~100%
τ'τ'ss14%14%
q'q'--ll++,,
WW++
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 21
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 22
Lepton+jets SignaturesLepton+jets Signatures
qq--
tt
tt--WW++
WW--
bb
bb--
νν
ℓℓ++
q 'q '-- qq
e/μ + jet
signalsignal
IP
SV
Jet 1
IP
SV
Jet 2
SV
IP
IP
SV
Jet 1
Jet 2
μ-
B hadron lifetime B hadron lifetime ττ ~ 1 ps ~ 1 ps B hadron travel LB hadron travel L
xyxy ~ 3 mm ~ 3 mm
before decaybefore decay
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 22
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 23
Lepton+jets SignaturesLepton+jets Signatures
qq--
tt
tt--
WW++
WW--
bb
bb--
νν
q'q'--
e/μ + jet
signalsignal
IP
SV
Jet 1
IP
SV
Jet 2
SV
IP
IP
SV
Jet 1
Jet 2
μ-
W + jets
3000 times higher rate backgroundbackground
q'q'
qq-- νν
gg
WW++
qq--
bb
bb--
1010 times higher rate
gg qq
qq-- qq--
bb
bb--
ggmultijets
ℓℓ++
ℓℓ++
“ℓ“ℓ””
qq--
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 23
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 24
Dilepton SignaturesDilepton Signatures
qq--
tt
tt--
WW++
WW--
bb
bb--
νν
νν
signalsignal
Z + jets
300 times higher rate
backgroundbackground
less statisticsless background
ee, eμ, μμ
ZZ
qq--
qq gg bb
bb--
ℓℓ++
ℓℓ--
ℓℓ++
ℓℓ--
--
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 24
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 25
Observation of the Top QuarkObservation of the Top Quark
1995, CDF and D1995, CDF and DØ Ø experimentsexperiments, Fermilab, Fermilab
17 events17 events
19 events19 events
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 25
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 26
Observation of the Top QuarkObservation of the Top Quark
1995, CDF and D1995, CDF and DØ Ø experimentsexperiments, Fermilab, Fermilab
17 events17 events
19 events19 events
March 2nd, 1995:First announcement of Top Discovery in public seminar at Fermilab
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 26
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 27
Observation of the Top QuarkObservation of the Top Quark
1995, CDF and D1995, CDF and DØ Ø experimentsexperiments, Fermilab, Fermilab
17 events17 events
19 events19 events
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 27
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 28
The Top Quark at the TevatronThe Top Quark at the Tevatron
2011, CDF and D2011, CDF and DØ:Ø:thousands of eventsthousands of events
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 28
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 29
The Top Quark at the TevatronThe Top Quark at the Tevatron
2011, CDF and D2011, CDF and DØ:Ø:thousands of eventsthousands of events → → in agreement with the Standard Modelin agreement with the Standard Model
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 29
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 30
2011, CDF and D2011, CDF and DØ:Ø:thousands of eventsthousands of events
The Top Quark at the TevatronThe Top Quark at the Tevatron
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 30
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 31
2011, CDF and D2011, CDF and DØ:Ø:thousands of eventsthousands of events
The Top Quark at the TevatronThe Top Quark at the Tevatron
0.5% accuracy!0.5% accuracy!
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 31
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 32
Single Top Quark ProductionSingle Top Quark Production
VVtbtb
direct measurement of |Vdirect measurement of |Vtbtb||
s-channel:s-channel: σtb = 1.04 ± 0.04 pb
NNNLOapprox
, mtop
= 172.5 GeV
t-channel:t-channel: σtb = 2.26 ± 0.12 pb
NNNLOapprox
, mtop
= 172.5 GeV
Vtb
tt missing Emissing ETT
leptonlepton
jetsjets
b-jetsb-jets
Vtb
PRD 74, 114012 (2006)
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 33
Single Top Quark ObservationSingle Top Quark Observation
|Vtb| = 1.07 ± 0.12 |V
tb| = 0.91 ± 0.11
5.05.0σσ
5.05.0σσ
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 34
Single Top Quark ObservationSingle Top Quark Observation
2009
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 35
Mass (GeV)Mass (GeV)protonproton
leptonsleptons
quarksquarks
neutrino masses neutrino masses ≪≪ 1 eV 1 eV
Particle MassesParticle Masses
(1976)
?
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 35
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 36
Particle MassesParticle Masses
Mass (GeV)Mass (GeV)protonproton
leptonsleptons
quarksquarks
W ZW Z goldgold
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 36
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 37
Particle MassesParticle Masses
Mass (GeV)Mass (GeV)protonproton
leptonsleptons
quarksquarks
W ZW Z goldgold
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 37
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 38
Particle MassesParticle Masses
Mass (GeV)Mass (GeV)electroweak symmetry breakingelectroweak symmetry breaking
protonproton
leptonsleptons
quarksquarks
W ZW Z goldgold
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 38
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 39
Search for the Higgs BosonSearch for the Higgs Boson
2nd Term 2012 Frontiers of Particle Physics II – Christian Schwanenberger – University of Manchester 40
BackupBackup
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 41
The DThe DØ Exper imentØ Exper imentThe DThe DØ Exper imentØ Exper iment
protons
antiprotons
Electronics
Tracker Solenoid Magnet
3 LayerMuon System
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 42
The DThe DØ Exper imentØ Exper imentThe DThe DØ Exper imentØ Exper iment
every396 ns …
Electron
Muon
Jet(experimental signatureof a quark or gluon)
2 nd Term 20 08 The Standard Model of Particle Phys ics – Chris tian Schw anenberger – Univers ity of Manches ter 43
The DThe DØ Exper imentØ Exper imentThe DThe DØ Exper imentØ Exper imentMissing transverse energy(experimental signatureof a non-interacting particle)