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Preparing for first physics at the LHC“th l f th t k”“the role of the top quark”
Complex SMEarly tops
SUSY
Extra dimensions
Early physics
NowCalibrations
Detector commissioning
Ivo van Vulpen (Nikhef)
The famous top quark
Paris Hilton Top Quark
… everybody constantly talking about them… they are troublemakers, famous, important … buy why again ?
2/57
Complex SM
SUSY
Complex SMEarly tops
Early physics
Extra dimensions
Now[6 slides]Calibrations
Early physics
[6 slides]
Detector
Calibrations
The Standard Modelcommissioning The Standard Model… and what’s wrong with it
Particles Forces
Quarks 1) Electromagnetism
2) Weak nuclear force
Leptons 3) Strong nuclear force
The Standard Model:Describes all measurements down to distances of 10-19 m
4/57
•4/52
Electroweak Symmetry breakingElectro-Weak Symmetry Breaking: (Higgs mechanism)
- Weak gauge bosons and particles have massR l t WW/ZZ tt i- Regulate WW/ZZ scattering
eV
)
“We know everything about the Higgs boson except its mass”
mass
(G
e
Limits on mh from theory
Limits on mh from exper.
Hig
gs
m
Triviality
V t bilit4222V Φ+Φ−= λμ
Λ (GeV)
Vacuum stability
5/57
The standard model … boring ?
“All measurements in “The Higgs boson will All measurements in HEP can be explained using the SM”
The Higgs boson will be discovered at the LHC at ~ 140 GeV”
No. … there are many mysteries left!
6/57
Wh t l i ( t ) t i f t hi h bl ?
The big questions:
What explains (extreme) tuning of parameters: hierarchy problem ?
What is dark matter made of ?
Why is gravity so different ? Why is gravity so different ?
The mysteries of the SM
Why is gravity not a part of the Standard Model ?
What is the origin of particle mass ? (Higgs mechanism)What is the origin of particle mass ? (Higgs mechanism)
In how many dimensions do we live ?
Are the quarks and leptons really the fundamental particles ?Are the quarks and leptons really the fundamental particles ?
Are there new symmetries in nature ?
Wh th l 3 f ili f f i ?Why are there only 3 families of fermions ?
Are protons really stable ?
Why is electric charged quantized ?
Why is there more matter than anti‐matter in our universe ?
What is the nature of dark matter and dark energy ?
Do quantum corrections explode at higher energies ?
8/57Why are neutrino masses so small ?
Standard Model is an ‘approximation’ ppof a more fundamental one.
Model breaks down at 1-10 TeVExtra dimensions ?
New phenomena will appear at distances ~ 10-19 mat distances 10 m
2009
Super-Symmetry ? String theory ?
Ed a d Witten’s Edward Witten’s latest insight ?
Complex SM
SUSY
Complex SMEarly tops
Early physics
Extra dimensions
NowCalibrations
Early physics
Detector
Calibrations
Th LHC l tcommissioning[9 slides]
- The LHC accelerator- The ATLAS detector
(testbeam, cosmics, beam)
The LHC machineThe LHC machine
Center-of-mass energy: 14 TeVCenter-of-mass energy: 14 TeV 7 x Tevatron
Energy limited by bending power dipoles1232 dipoles with B= 8.4 T working at 1.9k
Search for particles with mass up to 4 TeV
Energy limited by bending power dipoles1232 dipoles with B= 8.4 T working at 1.9k
Search for particles with mass up to 4 TeVSearch for particles with mass up to 4 TeV
Luminosity: 1033 1034 cm-2s-1
Search for particles with mass up to 4 TeV
Luminosity: 1033 1034 cm-2s-1 100 x LEP & Luminosity: 1033-1034 cm-2s-1
Phase 1: (low luminosity) 2009-2010Integrated luminosity ~ 10 fb-1/year
Luminosity: 1033-1034 cm-2s-1
Phase 1: (low luminosity) 2009-2010Integrated luminosity ~ 10 fb-1/year
100 x LEP & Tevatron
Integrated luminosity 10 fb /yearPhase 2: (high luminosity) 2010-20xx
Integrated luminosity ~ 100 fb-1/year
Integrated luminosity 10 fb /yearPhase 2: (high luminosity) 2010-20xx
Integrated luminosity ~ 100 fb-1/year
11/57
•11/52
Search for rare processesSearch for rare processes
Towards physics: LHC’s point of viewP. Jenny, SUSY2009
2009 2010 20112009
j f m a m j j a s o n d j f m a m j j a s o n d j f m a m j j a s o n d
2010 2011
Weltmeister !
shutdown
physics
- Start LHC operation Oct. 2009- Run over winter shutdown
physics- 10 TeV collisions first year
LHC operators: “44 days from first injection to physics run”
ATLAS/CMS: Analysis potential with ~100 pb-1 (ATLAS’ CSC note)
12/57
ATLAS/CMS: Analysis potential with ~100 pb 1 (ATLAS CSC-note)
The ATLAS detectorThe ATLAS detector
Tracking (|η|<2.5, B=2T) :Silicon, pixels and stripsTransition Radiation DetectorTransition Radiation Detector(e/π separation)
Calorimetry (|η|<5) :EM : Pb-LArHAD: barrel: Fe/scintillator
forward: Cu/W-LAr
Muon Spectrometer (|η|<2.7) : air-core toroids with muon chambers~1000 charged particles produced
over |η|<2.5 at each crossing.
Towards physics: ATLAS’ point of view
Testbeam Subdetector Installation Cosmics commissioningCosmics commissioning Single beams
First LHC collissions
First physics runs
2005 2006 2007 2008 2005 2006 2007 2008
14/57
Muons in the ATLAS cavern
~ 20 million muons enter cavern per hour
Simulation ATLAS cavern 0.01 seconds
Collected statistics:
ATLAS Preliminary Cosmics : tracks in Pixels+SCT+TRT
Debugging, first alignment studies
15/57
Muons in the ATLAS cavern
~ 20 million muons enter cavern per hour
Simulation ATLAS cavern 0.01 seconds
origin
Collected statistics:
ATLAS Preliminary
16/57
Cosmics: alignments & checks
Energy loss in calorimeterAlignment SCT barrel
After alignment
Before alignmentg
E t d 3 G V l
p(ID) – p(MS) [GeV/c]x residual [mm]
17/57
M Aleksa, P. Jenny, O. Jinnouchi SUSY2009
Expected 3 GeV loss
Cosmics: EM Calorimeter
Energy [GeV]
Entri
es
0
200
400
600
800
1000
1200
1400
1600
-0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Electromagnetic calorimeter Electromagnetic calorimeter
Energy [GeV]
Entri
es
0
200
400
600
800
1000
1200
1400
1600
-0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Test-beam dataATLAS Preliminary
En
trie
s
Muons
Test-beam data
nerg
y
Energy [GeV]
Entri
es
0
200
400
600
800
1000
1200
1400
1600
-0.4 -0.2 0 0.2 0.4 0.6 0.8 1
E
lati
ve E
Energy [GeV]
Entri
es
0
200
400
600
800
1000
1200
1400
1600
-0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Noise Re
Energy [GeV]
Entri
es
0
200
400
600
800
1000
1200
1400
1600
-0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Energy GeV Eta (module)
Check (+ correct) ECAL responseuniformity vs η to ~ 0.5%
A muon deposit ~ 300 MeV in ECAL cell (S/N~ 7)
18/57
Single beams in LHC
Beam gas + beam halo:- 5 TeV protons on residual gas in vacuum
- tracks accompanying the beam
19/57First beam event in ATLAS
Complex SM
SUSY
Complex SMEarly tops
Early physics
Extra dimensions
NowCalibrations
Early physics
[4 lid ]
Detector
Calibrations
- Planning road to new physics
[4 slides]
commissioning- Simple SM topologies(collecting pieces of the puzzle)
LHC start-up programme
Integrated luminosity
Look for new physics3
1 fb–1
Look for new physicsin ATLAS at 10 TeV
3
100 pb–1 Understand SM+ATLASin complex topologies
2
Higgs/SUSY
1
in complex topologies
Top quark pairs
10 pb–1
1 Understand SM+ATLAS in simple topologies
W/Z
p q p
0 Understand ATLAS Testbeam/cosmics
W/Z
Andreas Hoecker
21/57
TimeLHC startup
ATLAS detector performance on day-1
- Reconstruct (high-level) physics objects:
Electrons/photons: Electromagnetic Energy scale
Quarks/Gluons: Jet Energy scale + b-tagging
Expected detector performance from ATLAS
Neutrino’s/LSP?: Missing Energy reconstruction
Performance Expected day-1 Physics samples to improve
Expected detector performance from ATLAS(based on Testbeam and simulations)
ECAL uniformity 1% Min. bias, Z e+e- (105 in a few days)e/γ scale 1-2% Z e+e-
HCAL uniformity 2-3% single pions, QCD jetsJet scale <10% γ/Z (Z l+l-) + 1 jet or W jj in tt
22/57
Tracking alignment 20-500 μm Rφ Generic tracks, isol. muons, Z μ+μ-
Plan-de-campagne during first year
First year:Process #events
10 fb-1
A new detector AND a new energy regime
8
12
10W10 bb
U d d ATLAS
7
7-
8
10tt10 μ/μeeZ10 eνW
−++→
→ 1
21 U d t d SM+ATLAS
0 Understand ATLAS using cosmics
7
7
7
10G V150PjQCD10 bias Min.10 tt 21 Understand SM+ATLAS
in simple topolgies
d d2
4
5GeV) 130h(m
7T
10~~10 h
10 GeV150PjetsQCD
=
>
3
Understand SM+ATLASin complex topologies
2
3 4 TeV) 1g~(m 10 g~g~ = 3Look for new physics
in ATLAS at 10 TeV 3
23/57
Early SM peaks: di-lepton resonancests ts
J/ψ→ μμ
Y→ μμr o
f eve
nt
r o
f eve
nt
4200160
Y→ μμ
Nu
mb
er
Nu
mb
er
800
ATLAS preliminary, 1 pb-1 ATLAS preliminary, 10 pb-1
Mμμ (GeV) Mμμ (GeV)
E t d t L i it f 1031
Reconstruction efficiencies Muon spectrometer alignment Detector and trigger
Events per day at a Luminosity of 1031
24/57
Reconstruction efficiencies, Muon spectrometer alignment, Detector and trigger performance, Tracking momentum scale, ECAL uniformity, E/p scale, …
Top quarks:- As weird member of SM family- As a calibration tool in complex topologies
Complex SM
As a calibration tool in complex topologies- As a window to new physics
SUSY
Complex SMEarly tops
Early physics
Extra dimensions
NowCalibrations
Early physics
Detector
Calibrations
25/57
commissioning
The top quark: ‘old-physics’
We know already a lot about the top quark
u c t
d s b
Mass(difference), Electric charge (⅔), Spin, Isospin, Br(t Wb), V-A decay, FCNC Top Width Yukawa coupling
The LHC offers an opportunity for precision measurements
FCNC, Top Width, Yukawa coupling, ...
26/57
pp y pThe top quark is a trouble maker
Top quark production at the LHC
Cross section LHC = 100 x Tevatron
400,000/800,000 tt events per year at 10/14 TeV
90%Cross section LHC = 100 x TevatronBackground LHC = 10 x Tevatron
10%
tt
t
bbqqqq 4/9bbqqlv 4/9bblvlv 1/91) Top most complex SM candle bblvlv 1/9) p p
Clear signal on early data
2) Top signal important background
27/57
for most new physics searches
Top cross-section (theory)
aint
yna
l unc
erta
Frac
tion
mtop (GeV)
Uncertainty due to PDF’s similar to W/ZUncertainty due to PDF s similar to W/Z
28/57
Jianming Qian: http:// indico.cern.ch/conferenceDisplay.py?confId=54025
Scale dependence: NLO (approxNNLO): μF and μR varied separately (together)
Top cross-section (theory)
Dependence on √s
Factor 2
883 pb
401 pb
bbqqqq 4/9bbqqlv 4/9
√s (TeV)bbqqlv 4/9bblvlv 1/9
mt = 172 5 GeVm CTEQ 6 6
Topology: ‐ high‐PT (b‐) jets, ‐ isolated leptons
mt = 172.5 GeVm CTEQ 6.6
√s = 14 TeV: σapproxNNLO = 883 pb√s = 10 TeV: σapproxNNLO = 401 pb
29/57
‐missing energy
Top quark physics (with b-tag information)
Top physics is ‘easy’ at the LHC
Systematic errors on Mtop (GeV)in semi-leptonic channel
Selection: Lepton + multiple jets + 2 b-jetskills the dominant background from W+jets
Source Error10 fb-1
b-jet scale (±1%) 0.74 G
eV
j ( )
ISR/FSR Radiation 0.3
Light jet scale (±1%) 0.2
Top signal
f Evt
s/ 4
b-quark fragmentation 0.1
TOTAL: Stat ⊕ Syst ~ 1 GeVW+jetsN
r o
f
Mjjb (GeV)
30/57Could we see top quarks when selection is not based on b-tag ?
Di-lepton cross-section measurement (μμ)
Trigger: Single muon, PT > 17 GeV
nts
Lepton ID: Two, isolated, opposite chargePT > 20 GeV
of
eve
n
Jets: ≥2 jets with PT > 20 GeV
Missing ET: ET-miss > 35 GeV (+ cleaning)
Nu
mb
er
MZ-cut: |Mμμ–MZ| > 5 GeVNumber of jets
N
200 pb-1
tt signal = 327bckg = 87
31/57
S/√(S+B) = 16.1
Single-lepton Top quark events (no b-tag information)
• Robust selection cuts
Effi (%) # i l #b kMissing ET > 20 GeV1 lepton PT > 20 GeV3 jets PT > 40 GeV4 jets with P > 30 GeV
Effic (%) # signal #bckg
Muon 23.6 3274 1497
Electron 18.2 2555 11444 jets with PT > 30 GeV
W CANDIDATE
Electron 18.2 2555 1144
A i j t t t dHadronic 3-jet mass
TOP CANDIDATENote: In 70% of events there is an
extra jet with P > 30 GeV
• Assign jets to top decays
L=200 pb-1
j
extra jet with PT > 30 GeV
jet pairings ?
Hadronic top: three jets with highest vector-sum pT
32/57
Extra: Require a jj-pair in top quark candidate with |Mjj-80.4| < 10
Mjjj (GeV)
200 pb-1: few days of low-lumi LHC operation
Single lepton cross-section measurement (μ)
Data-driven estimate for W+jets from Z+jetsj j
20% uncertainty reachable
33/57
Top phase space
‘clean’
Top quark phase space
Top precision measurements
34/57
Top precision measurementsCalibrating ATLAS in multi-jet events
Top physics at the LHC
“Top quark pair production has it all”:
≥ 4 jets b jets neutrino lepton
4/9
≥ 4 jets, b-jets, neutrino, leptonseveral mass constraints for calibration
4/9
Calibrate light jet energy scale
A candle for complex topologies:
Obtain enriched b-jet sample
Calibrate missing ET
Calibrate light jet energy scale
Obtain enriched b jet sample
Leptons & Trigger Note the 4 candles:
- 2 W-bosons M = 80 4 GeV
35/57
- 2 W-bosons Mw = 80.4 GeV- 2 top quarks & Mt = Mt-bar
Jet energy scale
(1) Abundant source of W decaysinto light jets
Determine Light-Jet energy scale
– Invariant mass of (light-) jets should add up to well known W mass (80.4 GeV)
Light jet energy scale calibration (1% for 1 pb-1)
t
MW = 78.1±0.8 GeV MW(had)
1 G
eV
t
nts
/ 5
.
P
Eve
Pro:- Large event sample- Small physics backgrounds
Con:
36/57
S/B = 0.5Con:- Only light quark jets- Limited Range in PT and η
Using top quark events to obtain a clean sample of b-quarks
(2) Abundant clean source of b-jets Calibrate/test b-tagging in complex event topology
– 2 out of 4 jets in event are b-jets ~50% a-priori purity( t ISR/FSR j t )(extra ISR/FSR jets)
– The 2 light quark-jets can be g q jidentified (should form W mass)
t
t
Conventional:
- Rejection in di-jet sample
37/57
Rejection in di jet sample- Efficiency using semi-lept. decays
Estimating b-tag efficiency
Jet counting Likelihood / Topological selection
# jets with 0,1,2,3, 4 jets b-tags
Configuration depends on εb, εc εl
Fit templates to event characteristics
Co gu a o depe ds o εb, εc εl
100 pb-1: Δεb ~5%
38/57
Can also measure tt cross-section
Top group (all) ttH ttH
Extra jets
‘clean’low ‘ISR-FSR’ High-P
Exotics, SUSYTop group:
Top massCross-section
PTor
LargeET-
miss
Top quark phase space
SUSY
- Intro to SUSY
- SUSY parameter space( l di t ti l)
Complex SM
(early discovery potential)
- ATLAS’ SUSY reach
SUSY
Complex SMEarly tops
[11 slides]
Early physics
Extra dimensions
NowCalibrations
Early physics
Detector
Calibrations
commissioning
The hierarchy problemThe hierarchy problem in the SM
predicted observed t
Success of radiative corr. in the SM:
4532
129
91 boson Higgs
9.2 172.7 179 quark top+
+− ±
?
predicted observedW W
b32-ggb
mh =
Failure of radiative corr. in Higgs sector:Radiative corrections from top quark
h h
t
λt λt150 = 1354294336587235150
–1354294336587235000
mh p q
Hierarchy problem:
‘Conspiracy’ to get mh ~ MEW (« MPL)
t t
Λ241/57
p y g h EW ( PL)Biggest troublemaker is the top quark!
Λ
A new symmetry: supersymmetry
Standard model particles New ‘partner’ particlesStandard model particles
Bosons Fermion‐partners
New partner particles
BosonsW,Z,photon
e o pa e swino’s, zino’s, fotino’s
Fermionsquarks/leptons
Boson‐partnerssquarks/sleptons
SUSY: - Regulates quantum corrections (‘solves’ hierarchy problem)- Gauge Unification and dark matter candidate
42/57
- a-priori not very predictive (many parameters)- many constraints from data (no sparticles, cosmology, … )
A model: mSUGRA
R-parity conserved : - Stable Lightest Supersymmetric Particle: LSP
- m0: universal scalar mass (sfermions)- m : universal gaugino mass- m½: universal gaugino mass- A0: trilinear Higgs-sfermion coupling- sgn(μ): sign of Higgs mixing parameter- tan(β): ratio of 2 Higgs doublet v.e.v
mSUGRA
V)
Evolution of masses
ass
(G
eV
Fixing parameters at 1016 GeV, the renormalization group equations will give you all sparticle masses at LHC!
m0
m½
nn
ing
ma
Radiative EW symmetry breaking 1016 GeV
Ru
n
43/57
Radiative EW symmetry breaking(thanks to top quark)
Energy scale a.u.
mSUGRA parameter space
Allowed mSUGRA space m0 = 100 GeVm1/2 = 250 GeVtan β = 10
0(G
eV)
mSUGRAtan(β)=10
ATLAS 100 pb-1
(GeV
)
β
Mass spectrum800
700
600 gluino
m0
g-2
e m
ass
( 600
500
400
gluino
(WMAP)
Part
icle
300
200
stau LSP 100
0
Allowed mSUGRA space
m1/2 (GeV) Higgs boson(LEP) LSP (ΩDM)
Constraints:LEP: m > 114 4 GeV
44/57
pVery different exper. signatures
- LEP: mh > 114.4 GeV - Cosmology: LSP neutral- Cosmology: limits on mLSP
Cosmology and SUSY
WMAP III: 0.121 < Ωmh2 = nLSP x mLSP < 0.135
dark matter
ρ = Relic LSP density x LSP massρLSP = Relic LSP density x LSP mass
The relic LSP density depends on LSP mass:LSP stable, but they can annihilate, so density decreases when LSP annihilation cross section increases.
22~
2201
01 )/()( fmmmff +∝→ χχχχσ
01χ lepton
fχχ
3
22~
2 /)( χχρ
m
mmm fLSP
≈
+∝
0 lepton
slepton(NLSP)
45/57
χm≈01χ lepton
Upper AND lower limitson LSP mass
mSUGRA space: ATLAS reach
Allowed mSUGRA space (post WMAP)
ATLAS reach in mSUGRA space (1-lepton)
½(G
eV
)
0(G
eV)
mSUGRAtan(β)=10
ATLAS 100 pb-1
M½m
0
g-2
(WMAP)
stau LSP
M0 (GeV)m1/2 (GeV)
Allowed mSUGRA space
46/57
pVery different exper. signatures
Production of SUSY particles at the LHC
• Superpartners have same gauge quantum numbers as SM particles interactions have same couplingsas S pa t c es te act o s a e sa e coup gs
q q q~ qq
αS
gq q
αS
g~
• Gluino’s / squarks are produced copiouslyGluino s / squarks are produced copiously(rest SUSY particles in decay chain)
47/57
Event topology
jet jet lepton
lepton
Missing energyenergy
Missing
Topology: ≥4 jetsmissing ET (large)
energy
leptons/photons
SUSY events look like top eventsjetjet
48/57
LHC day 2: First to discover SUSY Common signature large fraction SUSY events
j t
SUSY event topology Sensitive to hard scale
jet
jet/lepton
jet
jet
jet/lepton
jet/lepton
b-1j / p
nts
/1
fb
# e
ven
SUSY SM
Meff (GeV)
SU(1) 232 tt 36SU(2) 40 total 42SU(3) 364
49/57tt production dominant background
SU(4) 896SU(5) 148
Estimate tt background in SUSY region: big fit
Top (sl)Top (sl)
Top (fl)
W+jets
SUSYSUSY
ET-miss MT mtop
50/5720% uncertainty on W+jets and ttVital for early claims of signs of breakdown SM
T T top
Complex SM
SUSY
Complex SMEarly tops
Early physics
Extra dimensions [6 slides]
NowCalibrations
Early physics
Detector
Calibrations
- New physics in the top sample(focus on resonances/high-PT)
commissioning- 2-slide intro to extra dimensions
Differential cross-section: structure in Mtt
Gaemers, Hoogeveen (1984)
n (
a.u
.)
500 GeV
s se
ctio
600 GeV
Cro
s
400 GeV
Mtt (GeV) Mtt (GeV)
Interference from MSSM Higgses H,A tt (can be up to 6-7% effect)
What about anomalous tt production ?ttXpp →→
52/57Z’, ZH, G(1), SUSY, ?
High PT-tops & anti-KT jetsTop Top
W)
Top Top
dR
(b
-W
Large boost: overlapping jets
pT top (GeV)
Large boost: overlapping jetstop algorithms break down
Use jet mass & look for sub-structure in jets (clustering)
Sociological side remark: - anti-KT jet clustering (thanks Gavin et al.)
53/57
- event weights in MC (thanks Max)- Fitting algorithms (thanks Göttingen)- … Δε and many many many others
The 3+1 forces of nature
reng
th
Quantum theories
strong force
Str
no quantum theoryt i th ?
Weak forcegravitation
1
string theory?Electromagn. force
1~Quantum gravity: gravitons
~1040 2~r
nr +2and mini black holes
Energy (GeV) ∝ distance-1
54/57
Planck scaleElectroweak scale
Kaluza-Klein excitations
Each particle that can ‘enter’ the extra dimension (bulk) will appear in our 4 dimensions as a set of massive states (Kaluza-Klein tower)
(Mreal)2 = E2 – px2 – py
2 – pz2 – pxd
2
= (m4d)2 – pxd2
Momentum quantized in the extra dimension. Pxd = i x ΔP , with i = 1,2,3,4,5, …
(m4d)2 = (Mreal)2 + pxd2
Depends on size/shape XD
massless graviton Gmomentum p0 p1, p2, …, pi in extra dimension
(4+n)-dim. R largeR small
tion
(a.u
)massive gravitonswith mass m0, m1, m2, …. miwith name G(0), G(1), G(2), …G(i)
(4)-dim.C
ross
sec
t
55/57
, , ,
Me+e- (GeV)
Drell-YanC
Resonances in Mtt
Z’, ZH, G(1), SUSY, ?
Resonanceat 1600 GeVn
ts
Resonances in Mtt
at 1600 GeV
# e
ven
Δσ/σ ~ 6 %
tt
Mtt (GeV) M (GeV)
56/57
Mtt (GeV) Mtt (GeV)
Complex SM
SUSY
Complex SMEarly tops
Early physics
Extra dimensions
NowCalibrations
Early physics
Detector
Calibrations
- Great journey ahead of uscommissioning- top plays an important role
- Plenty of early discoveries possible
Backup slides
Lepton trigger in multi‐jet eventsExtra (fake) muons
1) Apply all‐Jet Trigger (4J23)2) Look for events that pass muon
selection
Rate & origin
selectionFull Sim Fast Sim
extra/jet 100±4 107±8
from b / b-jet 250±10 268±21
•vfrom light / l-jet 6.3±1.3 9.1±3.0
fake / jet 3.5±0.7 0
M [GeV]
prob.for b‐jet (PT) to produce isolatedmuon Mjjj [GeV]
3) look at muon trigger performancei.e. an orthogonal trigger
muon
59/571 fb-1: εEF_mu20 = 0.801 ± 0.011 (stat)
g ggUse jet PT spectra and b/light rates
to get QCD estimates from data
A new symmetry: supersymmetry
SUSY: regulates quantum corrections (‘solves’ hierarchy problem)only works if the masses of the SUSY particles are close to that of SM partner
[ ]|| 2λ
y p p
[ ]K+Λ+Λ−=Δ )/ln(6216
|| 222
2fUVfUV
fH mmm
πλ
Notice minus sign
[ ]|| 2λ
Notice minus signNote 2 bosonic partners per fermion
[ ]K+Λ−Λ=Δ )/ln(16
|| 222
2SUVSUV
SH msmm
πλ
bosons
SUSY: - a-priori not very predictive (many parameters)- many constraints from data (no sparticles cosmology )
60/57
- many constraints from data (no sparticles, cosmology, … )
Commissioning the muon detectors
Full chain of muon reconstruction in ATLASStandalone tracking using cosmic rays
Large shaftsmall shaft
61/57origin cosmic rays
Flavour changing neutral currents
ATLAS 5σ sensitivityu (c,t)Z/γ
• No FCNC in SM:
u
L k f FCNC i t d
SM: 10-13 , other models up to 10-4
u,ct
• Look for FCNC in top decays
γ/Z( e+e-)
Expected limits on FCNC for ATLAS:- Results statistically limited- Sensitivity at the level of SUSY
62/57
- Sensitivity at the level of SUSY and Quark singlet models
