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Searches for Physics Beyond the Standard Model at LEP . Andre Tilquin CPPM Marseille. What is the Standard Model Why to go beyond and how Supersymmetry Higgs sector Exotica Summary. Is it working ?. One principle. Gauge symmetry or local invariance. ,Z 0 ,W  ,g. Exact symetry.

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Searches for physics beyond the standard model at lep l.jpg
Searches for Physics Beyond the Standard Model at LEP

Andre Tilquin

CPPM Marseille

  • What is the Standard Model

  • Why to go beyond and how

  • Supersymmetry

  • Higgs sector

  • Exotica

  • Summary

DIS2003 A.Tilquin


What is standard model l.jpg

Is it working ?

One principle

Gauge symmetry or local invariance

,Z0,W,g

Exact symetry

Yukawa

m=0

Broken with a Higgs SU(2) doublet

One observable H0

What is Standard Model

Three families

Three groups

DIS2003 A.Tilquin


Sm results and predictions l.jpg

Not so far….

SM results and predictions

DIS2003 A.Tilquin


Higgs mass constraint l.jpg

Higgs is needed by SM

Higgs mass constraint

DIS2003 A.Tilquin


Why to go beyond l.jpg
Why to go beyond ?

The NuTeV measurement:

-ratio of neutral current to charged current reactions in neutrino-nucleon scattering.

-When interpreted as a measurement of the mass of the W boson, a 2.9 standard deviations, from the other direct constraints is found.

Why not ?

DIS2003 A.Tilquin


How to go beyond sm l.jpg
How to go beyond SM

  • New symmetries:

    • -Super Symmetry

    • -New Gauge bosons

  • News Higgs fields: Doublets/triplets

  • New fermions

  • Anomalous coupling, contact interaction

  • Compositeness

  • More exotica:

    • Technicolor

    • Extra dimensions

DIS2003 A.Tilquin


Lep data set l.jpg

ALEPH

DELPHI

L3

OPAL

LEP data set

Per experiments:

LEP1: L175 pb-1

LEP2: L700 pb-1

Energies:

90209 GeV

DIS2003 A.Tilquin


The word of susy l.jpg

~

~ ~

h,H

~

Z

In exact SUSY no new parameters

}

~

~

01-4

~

}

~

g

~

~

lL,R

±1,2

=

~

L

~

q L,R

~

G

SUSY should be broken

The word of SUSY

  • Additional symmetry between bosons and fermions

    • Associates a SUSY partner to each SM particle

New multiplicative quantum number:

h,H,A

Z0

Rp=1 for SM particle

Rp=-1 for SUSY particle

g

Conserve

lL,R

L

LSP stable

Pair production

G

q L,R

DIS2003 A.Tilquin


Breaking down susy l.jpg
Breaking down SUSY

  • Its mechanism is unknown: Many models

    • SUGRA (Super Gravity)

      • LSP=neutralino

    • GMSB (Gauge mediated Super symmetry breaking)

      • LSP=gravitino

    • AMSB (Anomaly Mediated Super Symmetry breaking)

      • LSP=wino-like

Standard MSSM

DIS2003 A.Tilquin


Standard mssm l.jpg

All final states characterised by missing energy

Standard MSSM

  • Supergravity inspired minimal models with R parity

    • Heavy gravitino and gluino

    • Stable, neutral and weakly interacting LSP 10

  • Low energy parameters:

  •  Higgs mixing mass term

    tan() v.e.v

    mA CP odd higgs mass

    m1/2 Common gaugino masse at GUT scale

    m0 Common sfermion mass at GUT scale

    A0 Common trilinear mass at GUT scale (mixing)

    Production at LEP:

DIS2003 A.Tilquin


Slepton searches l.jpg

e+

,Z*

e+

e-

e-

Slepton searches

2 acoplanar leptons + missing energy

Main background from WWll

DIS2003 A.Tilquin


Squark an gluino l.jpg

Squark missing angle

Squark an gluino

qL and qR are mixingq1,q2

e+

,Z*

e-

To compare with Tevatron,LEP results are translated into an exclusion limit in gluino an squark masses

DIS2003 A.Tilquin


Chargino and neutralino l.jpg

e+

,Z*

e-

W(*)

Z(*)

Chargino and neutralino

Production at LEP:

Decay:

DIS2003 A.Tilquin


Neutralino l.jpg
Neutralino

Chargino, neutralino slepton and Higgs results are combined.

LSP mass limit obtained at high tan()

DIS2003 A.Tilquin


Mssm higgs l.jpg

e+

Observed limit in the mhmax scenario:

mh>91.0 GeV (94.6)

mA>91.9 GeV (95.0)

,Z*

e-

e+

,Z*

e-

MSSM Higgs

  • Two Higgs doublets:

  • 5 physical states:

  • h,H,A and H

  • Two free parameters at tree level: mA,tan=v2/v1

  • Searches by combining two complementary processes

Dominant at low tan()

Dominant at high tan()

DIS2003 A.Tilquin


Flavor independent higgs search l.jpg

Observed limit for:

=SM

Br(h hadrons) = 100%

mh>112.9 GeV/c2

Flavor independent Higgs search

  • Some extension of standard model:

  • Two Higgs doublet (type II models), the mixing angle in the CP-even Higgs sector is a free parameters

  • standard decay hbb or  could be suppressed w.r.t hcc or gg

  • Searches for hadronic decay without b tagging.

DIS2003 A.Tilquin


Charged higgs l.jpg

e+

,Z*

e-

mH>78.6 GeV/c2

Charged Higgs

Predicted by 2 HDM models.

Decays:H/cs

B(H) free parameter

Main background WW

DIS2003 A.Tilquin


Invisible higgs l.jpg

For =SM and B(hInv.)=100%

Mh>114.4 GeV/c2

Invisible Higgs

  • Predicted in different models:

  • In MSSM:

    • h00

  • Majoron

    • hJJ

  • Cross section can be different from standard model.

  • Search for acoplanar jets and leptons from Z decay

DIS2003 A.Tilquin


Fermiophobic higgs h l.jpg

Fermiophobic:

mh>109.7 GeV/c2

h

W(*)

Fermiophobic Higgs:h

  • In some models:

    • Type I 2HDM

  • No couplings to fermions. Coupling to photons through W loop:

    • Anomalous couplings

DIS2003 A.Tilquin


Double charged higgs l.jpg

OPAL: mH>98.5 GeV/c2

Double charged Higgs

Predicted by LR super symmetric model (Higgs triplet):

Decay in two charged leptons, mainly in tau’s. Yukawa coupling to lepton is free parameter.

h>10-7 : look for 4 ’s close to interaction point

h<10-7 : search for kick of charged tracks

h<10-8 : search for anomalous ionisation

DIS2003 A.Tilquin


Anomalous top quark coupling sm 10 9 fb l.jpg

l,q

W

,q

e+

t

b

e-

Anomalous top quark coupling SM10-9fb

Single top production at LEP (FCNC)

R-parity violation

kZ ,kg

Delphi

DIS2003 A.Tilquin


Excited fermions l.jpg

f/

,Z,W,g

e+

e*

e-

Excited fermions

In composite models, fermion & boson are composite with and associated energy scale .

gauge group weights factor

Lot of decay channel at LEP:

From differencial x-section

DIS2003 A.Tilquin


Lepto quark l.jpg

e+

,Z

LQ

LQ

e-

I3

OPAL Preliminary

OPAL

e+

LQ

e-

Lepto-quark

  • Very similar to excited leptons:

    • New color triplets bosonic fields mediating interaction between quark and leptons (LQ)

DIS2003 A.Tilquin


Heavy leptons l.jpg

L+(N)

e+

,Z

e-

L-(N)

l,L(stable)/l+

L±/N

f

W*

Heavy Leptons

  • One way to explain the  mass in the see-saw mechanism

    • New heavy leptons with

DIS2003 A.Tilquin


Technicolor l.jpg

e+

e+

e-

e-

Technicolor

Alternative mechanism of Electro-weak Symmetry Breaking:

  • Breaking of global chiral symmetry of technifermions generates Golstone boson used for longitudinal polarisation of massive W and Z bosons.

  • Techniquark condensate replace non zero VEV of Higgs field

  • Need a large number of technidoublets (ND=9)

  • Vector states r0T, w0T p+T p-T or g p0T

    • Technipions couple to quarks and leptons µmass

DIS2003 A.Tilquin


Extra dimensions l.jpg

Number of ED

Planck mass

Planck mass in ED

Radius of extra dimensions

Extra dimensions

  • Trying to solve the hierarchy problem:

    • Weakness of Gravity at electroweak scale

  • Our word confined to four dimensions

  • Gravity propagates in extra dimensions (ADD)

By choosingMDEWNo hierarchy problem

Small but large number of states (GKK)

1/MPl

f,V

d=1 R=1013 m Excluded

d=2 R=1 mm

d=3 R=1 nm

….

d=7 R=1 fm Max in M-theory

G

f,V

DIS2003 A.Tilquin


Extra dimensions cont l.jpg

For n=2

MD>1.36 TeV

Extra dimensions (cont)

Direct search: missing energy

LEP average:

MS>1.2 TeV (=+1)

MS>1.09TeV (=-1)

Indirect: look for deviation from (d/d)SM

DIS2003 A.Tilquin


Conclusions l.jpg
Conclusions

Lot of searches performed by the 4 LEP experiments

SUSY: No evidence at LEP and CMSSM fully covered

Chargino: m>94 GeV

Neutralino: m>45 GeV

Sparticles:m>100 GeV

Higgs sector: No evidence of non standard Higgs

mHiggs 100 GeV/c2

Exotica:

New particles: m>100 GeV/c2

New scales > 1 TeV

New coupling < 10% SM couplings

No deviation from standard model, and no evidence of new physics.

Hope that something will happened at LHC

DIS2003 A.Tilquin


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