05/11/2006Prof. dr hab. Elżbieta Richter-Wąs Physics Program of the experiments at L arge H adron...

05/11/2006Prof. dr hab. Elżbieta Richter-Wąs

Physics Program of the experiments at

Large HadronCollider

Lecture 5


Outline of this lecture

Physics programme: Higgs boson in SM and MSSM model


“Theoretical” basics

FermionsFermions SymmetriesSymmetries Bosons, InteractionsBosons, Interactions

Three families,Three families,with with leptons

and and quarks

1) 1) Poincaré GroupPoincaré Group

2) 2) Gauge Symmetries:

U(1)U(1)Y Y

SU(2)SU(2)LL

SU(3)SU(3)cc

: QED, : QED, g’

Z, W : Weak, : Weak, g

(electroweak unification)(electroweak unification)

8 gluons : QCD, : QCD, gs

uL

dL

, uR, dR.

eL

eL

, R, eR,

g

gW

tan

Only known solution: the Higgs Mechanism

c

s

t

b


“Theoretical” basics

+ Self-interaction via V():

432

2

22

!4!3

v

3

v

2

1

2/v!3

)(

HHH

V

mf/v

m2 /v

m2 /v

m2 /v2

W,Z

H

m2 = v2/3H

(unknown)

All couplings predicted

Mass unknown

22 2/v!3

)( V

--vv44/24/24

Empty vacuum

(Our vacuum)

Matter interacts with the quantum fluctuationsof the vacuum as well as with the vacuum itself

Ad hoc coupling


“Theoretical basics”: are there bounds on mH?

Triviality bound

2

H

22

H m34

expmv 22

2F2

H /logF8

2G3m v

=mH2/v2

As for any other coupling constant, the particle content of the standardmodel determines the running of up to a scale , at which the model is no longer valid. )(0

Vacuum stability


Higgs: Introduction


Higgs: Present status of knowledge


Higgs: production at hadron colliders


Higgs boson branching fractions


How can one claim a discovery?


Maximising significance


H


Simulated H


H backgrounds


H irreducible backgrounds


H expected performance


Tile Calorimeter

Forward calo

EM LAr EndcapEM LAr Barrel

Had. endcap

H

H needs mass resolution ~ 1%

response uniformity ≤ 0.7%e.m. calorimeter energy

m(GeV)105 135120

over | | < 2.5

As example : LAr electromagnetic calorimeter


End-cap wheel in vertical position (End-cap wheel in vertical position (24/6/0324/6/03))

• Thickness of 1536 plates for EM endcap

measured with ultrasounds during construction

thickness of Pb absorber plates must be uniform to ~ 0.5%(~ 10 m)

• To keep energy response uniform to ~ 0.2-0.3%

LArPb

Pb+

-+ +

--

absorber

absorber

~ 9 m=2.2 mm

e

EM Endcap EM Endcap : Construction requirements: Construction requirements


• Test of 4(Test of 4(out of 32out of 32) barrel, 3() barrel, 3(out of 16out of 16) end-cap final modules ) end-cap final modules

BC1BC1 BC2BC2 BC3BC3 BC4BC4

S1S1

pionpion counter countermuon countermuon counter

FeFeS3 ,4 PbPb

Barrel module scan with high E electrons

=0

=46

=0

=15

• Required uniformity in regions of size x = 0.2 x 0.4 ~ 0.5% (440 regions in the full ECAL)

H8 beam line

EM BarrelEM Barrel: 1999-2002 test beam: 1999-2002 test beam


x

z

y

Geant4 simulation of test-beam set-up

~ O(1%) of ATLAS tested on CERN H8 beam line

•«final» electronics

•«final» detectormodules

monitoring

• ATLAS softwareto analyze data.

Toward PhysicsToward Physics: 2004 ATLAS : 2004 ATLAS CCombined ombined TTestest B Beameam


TRT LAr

Tilecal

MDT-RPC BOS

Pixels & SCT

TRT LAr

xz

y

• 90 millions events collected( ~ 4.5 TB)• e±, ±, ±, @ various energies, B=01.4 T

beam

Toward PhysicsToward Physics: 2004 ATLAS : 2004 ATLAS CCombined ombined TTestest B Beameam


Ece

ll(G

eV)

Linearity

E/E

bea

mconstant term~0.7%

E(GeV)

Energy resolution(1 cell)

/E

(%)

Ebeam (GeV)100 200 100

points well within 1%

• Work in progress to understand the material in the beam line

200

Uniformity (e- 180 GeV) over 22 spots

0 0.62

9 GeV beam energy pb?

Electronics calibration pb

Uniformity~ 0.5%

CTB: CTB: electron studies electron studies(preliminary results)(preliminary results)


H ZZ(*) llll


Simulated H ZZ(*) llll


Simulated H ZZ(*) llll


H ZZ(*) llll: control of reducible background


H ZZ(*) llll: analysis


Vector boson fusion


Forward jet tagging


Example: qqH qqWW* qqll


Overall SM Higgs discovery potential


Overall SM Higgs discovery potential


Determination of Higgs boson parameters


Higgs mass determination


Higgs width determination


Determination of couplings


Determination of couplings


Measurement of partial widths ratios


Higgs pair production and self couplings


MSSM Higgs sector


Production cross-section


Higgs decays


h , bb


A/H


A/H : mass reconstruction


A/H : lepton-hadron analysis


A/H


Charged Higgs


Summary 30fb-1


LHC discovery potential for SUSY Higgs bosons


What can we do in one year?


Conclusions

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05/11/2006Prof. dr hab. Elżbieta Richter-Wąs Physics Program of the experiments at L arge H adron...

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