BSM at the LHC

Dirk ZerwasLAL Orsay

• Lecture I: • LHC and the Detectors• Standard Model

• Lecture II:• The standard model Higgs boson• The supersymmetric Higgs bosons

• Lecture III:• Supersymmetry• Exotics

• proton-proton collisions• Ebeam=7TeV• s = 14TeV• 0.15-20*s effective• tunnel circumference: ~27km

2 Multi-purpose detectors: ATLAS, CMS

B-Physics: LHCb

Heavy-ion physics: ALICE

Totem

LHC

LHC

ILC

LHC

ALL Dipoles installed

R=p/(B q c)

B=8-9TsupraconductingP=7TeVc=3*108m/s

R=2.7km LHC: 4.3km

Straight sections

1600 superconducting magnets….Preparations started in 1990…Installation started in 2001…

standard refrigerator: 276KLHC: a 27 km fridge at 1.9K

37000 tons of equipment1 year of cooldown120 tons of Helium (1 truckload=5t)!

• energy in beams: a Boeing 737 at landing speed • 60 kg of TNT (beam dump)

LHC: 2008/2009

III

No beam

Beam

ShutdownMachine checkout

7TeV

Beam setup

25ns ops I Shutdown

Stage I II III

No beam

Beam

Hardware commissioning

5TeV

Machine checkout

5TeV

Beam commissioning

5TeV

43 bunch operatio

n75ns ops 25ns ops I Shutdown

2008

2009

2008:• Goal 5TeV (Magnets)• 43/156 bunches per beam (of 2800)• 75ns (13.3MHz)• 25ns (nominal: 40MHz)

We are here

~ 25% of nominal I

~ 45% of nominal I

Evolution of beam levels and luminosity

0

20

40

60

80

100

120

140

160

180

1 2 3 4 5 6 7 8 9 10 11 12

Operational phase

Inte

ns

ity

(101

2 ), s

tore

d e

ne

rgy

(MJ

), e

ve

nt

pil

eu

px

10

0.00E+00

5.00E+32

1.00E+33

1.50E+33

2.00E+33

2.50E+33

Lu

min

os

ity

Beam intensity Stored energy Event pileup Luminosity

Stage I Stage II Stage III

11

m,

43

bu

nc

h,

4 1

010

2m

, 4

3 b

un

ch

, 4

101

0

2m

, 1

56

bu

nc

h,

4 1

010

2m

, 1

56

bu

nc

h,

9 1

010

11

m,

75

ns

, 4

101

0

2m

, 7

5n

s,

4 1

010

2m

, 7

5n

s,

6 1

010

1m

, 7

5n

s,

9 1

010

11

m,

25

ns

, 4

101

0

2m

, 2

5n

s,

4 1

010

1m

, 2

5n

s,

5 1

010

0.5

5m

, 2

5n

s,

5 1

010

1.00E+32

kb N * 1,5

(m)

IBeam

proton

Luminosity

(cm-2s-1)

Events/

BC

43 4 1010 11 1.7 1012 7 1028 << 1

156 9 1010 2 1.4 1013 1.1 1032 3.9

2808 5 1010 0.55 1.4 1014 1.9 1033 3.6

43/156 Bunches 75ns

2007/2008 25ns PhaseI

End 2008

LHC: integrated Luminosity

L=1032cm-2s-1

1fb-1 p.a.

L=1033cm-2s-1

10fb-1 p.a.

• bunch 1011 protons • every 8m• 40Mhz • reality ~ 32MHz(empty bunches)

L: luminosityN=σ∫Ldtt typically 107s

LHC: comparison to other Machines

Beam (L=1034, 1.1x 1011 p/bunch)• 60 kg TNT• fully loaded Airbus 320 at landing speed

Rule of thumb:• around 2010 ~10fb-1 p.a.• well after 2010 ~100fb-1 p.a.

ATLAS and CMSLength: 45mRadius: 12mWeight: 7000TonnenReadout Channels: 108

3000km cables

Track Reconstruction (|η|<2.5, B=2T)• Si Pixels and Strips• Detector for Transition Radiation (TRT) for PIDCalorimeter (|η|<5)• EM: Pb-LArgon 10%/E0.7%, long. Segm.• HAD: Fe/Scintillator (central), Cu-W-Lar (fwd)Muon chambers (|η|<2.7):• Toroids with Muon chambers (MDT)

Length: 22mRadius: 7mWeight: 12500Tonnen

Track reconstruction (|η|<2.5, B=4T)• Si Pixels and StripsCalorimeter (|η|<5)• EM: PbWO4 2%/E0.7%• HAD: Brass/Scint., Fe/Quartz (fwd)Muon chambers (|η|<2.7):• Solenoid Return Yoke instrumented with Muon chambers

CMS = Compact Muon Solenoid

Length: 22mRadius: 7mWeight: 12500 tons

Length: 45mRadius: 12mWeight: 7000tons = 100 Boeing 747Readout channels: 100Million3000 km cables

ATLAS= A Toroidal Lhc ApparatuS

building 40at CERN6 stories

Event reconstruction

Electrons and Photons:

Tracks: InnerDetector(with lifetime information for b-tagging)

Electrons/photons: EM Calorimeter

Jets: Calorimeters

Muons: InnerDetector and muon detectors

Before Physics: Calibration

Trigger

Calibration and Alignment of the detectors:Electronic Calibration

In situ Calibration and Alignment:• Zee, Z μμ : Alignment, Calibration ECAL (Z mass), Particle-ID, muon chambers• W lν : Energy/Momentum Calorimeter/Tracker • tt bWbW blν bjj : Reconstruction W from hadronic decay • Z ττ: tau-Lepton Reconstruction (Z mass, Efficiency),ETmiss• γ+Jets, Z(ll) +Jets: Jet Calibration (Recoil against Z,γ)

108

107

105

103

10

10-1

10-3

Events per Second 1033 cm-2s-1

Events for 10fb-1:W eν, μν 150 MZ ee, μμ, ττ je 15 Mtt 8 MJets (>200GeV pT) 1000 M

JES: 1%LES: 0.1%ETmiss: (0.5-1)/ET

Particle Reconstruction: electrons/photons

The reconstruction sequence for electrons and photons:• Calibration of Electronics and Alignment• Clustering (Sliding Window)• Corrections at the cluster level:

• position corrections • correction of local response variations• corrections for losses in upstream (Inner detector) material and longitudinal leakage

• Matching with Tracks • Identification• 2nd stage reco:

• Refinement of corrections depending on the particle type (e/γ) • Bremfit/Gaussian Sum Filter

• uniformity 0.7% with a local uniformity in ΔηXΔφ=0.2x0.4 better than 0.5% • inter-calibrate region with Zee

Energy calibration for electrons and photons

Optimize Energy resolution AND linearity!

0.1%-0.2% spread from 10GeV to 1TeV over all eta!Essential to mesure particle masses correctly with the best precision

100GeV

impactcellbremleaki

caloi

visVisPS

VisPS

rec fEfdepthfEEdEEEcEEbEaE 3,1

5.01 ).()).(1).().().)(().()((

E loss upstream of PS E loss PS and calo

calo sampling fraction+ lateral leakage E dependent

Longitudinalleakage

Systematics at low energy ~0.1 %

Testbeam: Achieved better than 0.1 % over 20-180 GeV

Uniformity and Identification

rms0.62%

0.45%

0.49%

Uniformity: ensure same energy response Higgs (later)

Identification: differentiate electrons from jets Large QCD cross section

Jets and ETmiss

Calibration e/pi response Jet clustering

Jet resolution: 60%/E 3%Jet energy scale: 1%

Typical signature of SUSY

compensation for dead matter etc

ETMiss at 2000GeV:ATLAS σ=20GeVCMS σ=40GeV

ETmiss

Trigger@LHC

Trigger@LHC: Example of a typical menu

Luminosity Measurements at the LHC

100fb-1 25 interactions per beam crossingInstantaneous luminosity decreases with beam lifetimeIntegrated Luminosity: N = σ * L (every rate/Xsection measurement depends on it)

1.Online measure events in 3<|η|<5Counting zero ET towers (ET<0.5GeV):

2. Measure elastic cross section at small anglesTOTEM at 150m, 200m

Deviation at High Luminosity

Use optical theorem to relate total Xsection to elastic cross section extrapolated to 0

Measurements done at 1028cm-2s-1

Extrapolation of beam optics necessaryPrecision on σtot ~1%

3.Standard Candles:W production: 300HzZ production: 30Hz (PDF uncertainty)

Minimum Bias

A glossary:Minimum Bias: Trigger thresholds “minimal”, measures the total XsectionUnderlying event:= “rest” when subtracting “hard process”, e.g. production Z

Minimum Bias: Large uncertainties for the extrapolation from TeVatron to LHC

Standard Model: W production

ss 3

1

2

1

Tevat

ron

x: fraction of proton momentum

Q2 :

sq

uar

e of

mom

entu

m t

ran

sfer

z

zW pE

pEy ln

2

1

-6 -4 -2 0 2 4 60

1

2

3

4

5

x1 = 0.0003

x2 = 0.12

x1 = 0.12

x2 = 0.0003

x1 = 0.006

x2 = 0.006

yW

MRST2002-NLO LHC

dW

/dy W

. B

l

(nb)

W±

WW ys

Mx exp2,1

Pseudo-rapidity: -ln (tan θ/2)(polar angle)Masses neglected

Rapidity:

Parton collisions (ex quark):

The LHC is a gluon-collider!

gluon pdf

Standard Model: QCD

CMSCMS Jet-Production• with 10fb-1

• compare with NLOBUT:• E-Calibration• prediction for PT >1TeV

large errors above 1TeV• energy scale• PDFs

The Standard Model: W Mass

Sensitivity to mW (leptonic decays, hadronic case hopeless)

The Standard Model: W Mass

Scale Method:Treat Z as W and shift spectra

electron

muon

Selection:PT(lepton)>25GeVETmiss> 25GeVJet Veto PT>30GeV

Statistics

10fb-1

15

<20Tot. Exp.

BSM: Di-boson Production

TripleGaugeCouplings (TGC): WW+γ ou WZ(ll)300fb for PT(γ)>100GeV

Selection: • PT(γ)>100GeV• PT(Lepton)>40GeV• mT>35GeV• isolation of Photon and Lepton• Jet Veto

λγ=0.01

W rest frameWγ frame

D0 (2005) (162pb-1): -0.93<Δκγ<0.97|λγ|<0.22

LEP: g1

Z=0.984±0.02κγ=0.973±0.045λγ=-0.028 ±0.021

The top quark

Indirect sensitivity to the Higgs boson mass

TeVatron 2008: 172.4 ± 1.2 GeV (0.7%)

Production and decay of top quarks

Decay (before hadronization):

• short lifetime : top ~ 410-25 s

• decay channels:

– t W+b because mtop > MW

– with W+ e+e, + (, +)

– or:

– W+ ud, us, cs

g

gg

t

t

q

q

t

t

au Tevatron: 10% 90%

au LHC: 90% 10%σLHC = 833 pb = 100σTeV

Final states (classified according to W decays, excluding taus):

• fully leptonic channel 5% 450000evts/year low bg

• semi-leptonic channel 30% 2,700,000evts/year good sg/bg

• fully hadronic channel 44% 4,000,000evts/year large bg QCD

ttb+jjb in ATLAS

Missing energy

muon

Hadronic jet

Hadronic jets

NNbtag btag = 2= 2

• Reconstruct the W bosons

– select (jj) minimizing |mjj – mW|

– W purity: 66%

– efficiency : ~80%

• Light jet calibration of W

– Energy calibration 1-2%

Measurement of the top quark mass: semi-leptonic channel

σ = 7.4 GeV

• Reconstruction of hadronic top quark top

– association of b jets with W boson:

– largest pTtop

– maximize ∆R(l,b)

– minimize ∆R(b,Wjj)

purity top : 69%

efficiency : 1.2%

• Number of events

• ~30K (80K) events in 2 b-tag (≥1b-tag)

• physics background ~ 100 events !

• resolution : σ ≈ 11 GeV

Measurement of the top quark mass: semi-leptonic channel

σ = 10.6 GeV

• fully hadronic channel:

– 6 central jets (high pT) 2 b

– ~ 100,000 evts in 10 fb-1

• combinations and selections:

– W jj (2W)

– t Wb (2t)

– 130 < |mjjb| < 200

– pTtop ≥ 200 GeV/c

– resolution 13 GeV/c^2

– S/B: 18/1

Measurement of the top quark mass

Δmt(GeV)

light jet energy scale 0.8

b-jet energy scale 0.7

Initial State Radiation

Final State Radiation

0.4

2.8

b-quark fragmentation 0.3

Background 0.4

Total SYSTEMATIC 3.1

Total STATISTICAL 0.2

δmt

b-jet energy scale (1%) 0.6

b-quark fragmentation 0.7

ISR / FSR modeling 0.6

Parton Distr. function 1.2

Total SYSTEMATIC 1.6

STATISTICS & method 0.3

fully leptonic performance with 10 fb-1

– Evt/evt: mt solve system weight

– all evts: mean weight per m

– mtfit = mt w/ highest <weight>

σ ≈ 13 GeV/c2

• Polarisation of the W boson in top decays: search for deviations from the standard model

– Decay t W+b

– 3 helicity states possible for a W boson: -1,0,+1

“Left” “Longitudinal” “Right”

FL=mt2/(mt

2+2mW2) F0=2mW

2/(mt2+2mW

2) FR= 0.00

= 0.703 = 0.297 = 0.00

b

t

W

b

t

W

W

t

b

Coupling

Limit 2 (statsyst)

0.31 0.14 0.07

Rf1Lf2

Rf2

(standard model: f1L = Vtb1 , f1

R = f2L = f2

R=0)

W Polarisation and the Wtb coupling

lepton: sign and direction wrt Wreco of decay angle possible

..)(2

)(2

2211 chtPfPfbWg

tPfPfbWg

L RR

LL

RR

LL

Determine FL, F0, FR and translate to fiL,R

mecanisms:

The final standard model topic: single top production

t channels channel W+t channel

• Backgrounds: tt, W+jets, QCD-jets

NLONLO= 231± 9 pb= 231± 9 pb NLONLO= 10.1 ± 0.7 pb= 10.1 ± 0.7 pb LOLO= 60 ± 15 pb= 60 ± 15 pb

Clear signal