F. Richard Feb 2003

A Z’ within the ‘Little Higgs’

Scenario

The LHC/LC Study group meeting

CERN

F. Richard Feb 2003

Introduction

2 examples of LHC/LC complementaritycan be imagined: Assume that a mass peak is

observed at LHC in l+l- : which interpretation can be given (Extended groups, KK, Little Higgs…) Assume that LHC finds a Higgs massincompatible with LEP/TevatronpredictionCan FLC solve the puzzle ?Could this new input have an impact on LHC or Super-LHC ? In this talk, I will illustrate these ideas within the ‘Little Higgs’ scenario

F. Richard Feb 2003

LEP1/SLD results

With LEP1/SLD leptonic asymmetries mH ~40 GeV Same is true from W mass Correlated effects through mt

~2 significance (Tevatron can improve)

AbFB gives mH ~600 GeV 3 discrepancy

New physics (mixing with new heavy fermions) or experimental bias ?

This result will be ignored Speculative ideas for ALR and mW :

G. Altarelli et al. SUSY V.A. Novikov New generation T. Takeuchi -N mixing + mH + U

contrib What about a Z’ ?

F. Richard Feb 2003

F. Richard Feb 2003

A Z’ Scenario

Extended GUT groups like E6 or SO(10) predict Z’/ or ZR WR

Several other motivations like R, parameter, LR symmetry restoration…

TeV xtra-dimensions with KK excitations

of Z/ (Antoniadis et al), String models ‘Deconstruction’ (Arkani-Hamed et al)

A Z’ at 1 TeV + mixing allows for a heavy Higgs boson(Peskin and Wells)

Could explain an apparent light H at LEP1/SLD

With so many competing models it might be difficult to interpret a Z’ signal at LHC (LHC/LC Complementarity)

F. Richard Feb 2003

Deconstruction

Bottom up approach: cancel quad divergences

Top bottom approach More dimensions ~ more symmetries->Theories with replicated symmetries which create the right low energy structure (reminiscent of QCD) ->Higgs is a pseudo-goldstone boson, with its mass stabilized without SUSY->Perturbative theory which becomes strong at 4f~10-100 TeV

F. Richard Feb 2003

Little Higgs

Phenomenology requires that there be extra gauge bosons, extra quarks,extra scalars

‘Littlest Higgs’ the minimal version is used here (JL Hewett et al. C. Csaki et al.)

There are 3 parameters : 2 couplings Bh xg’(Q-I3) Zh ygI3 1 mass scale f

No mixing for x=1 but then interference operates at LEP2

Contribution to finite at x=0

LEP/SLD ‘prefers’ f~5 TeV and low x with a 115 GeV Higgs

F. Richard Feb 2003

F. Richard Feb 2003

N. Arkani-Hamed et al hep-ph/0202089

F. Richard Feb 2003

mH=115 GeV

F. Richard Feb 2003

LEP/SLD prefers low x -> Bh heavy

FT problem with mH=115 GeV f=5 TeV

f < 1 TeV (mH/200 GeV)2

No problem with mH > 300 GeV 3 < f < 5 TeV at LEP/SLD Very distinct behavior from other Z’

models (x fixed) or from SUSY (mH)

LEP/SLD cannot predict accurately masses mBh ~ f (0.1/x) mZh > 3 TeV

m > 7 TeV mt’ > 9 TeV out of reach

(weak contribution to LEP/SLD)

Interpretation

F. Richard Feb 2003

mH=500 GeV

F. Richard Feb 2003

LEP/SLD + FT

Forbidden

Allowed

F. Richard Feb 2003

F. Richard Feb 2003

F. Richard Feb 2003

Predictions from FLC

With mBh~f (0.1/x)

-> Close to the LHC limit ~4 TeV

GigaZ would give adequate precision on Bh M/M ~(M/7 TeV)2

Interference at FLC can tell if Zh within LHC reach ~(M/6 TeV)4

-> FLC can tell if these masses within the LHC range

F. Richard Feb 2003

Stephen Godfrey hep-ph/0201093

F. Richard Feb 2003

UED Scheme

LH with x -> 0 behaves like the Universal Extra Dimension model

In UED each particle has KK partner but ZKK not coupled to e+e- (no interference with Z)

Weak isospin violation measurable: ~ (mtopR)2 (Appelquist et al.)-> mKK > 300 GeV with mH=115 GeV

If H at 500 GeV mKK ~ 200 GeV-> Accessible at TeVatron and FLC

GigaZ can predict mKK with good accuracy ~ (mKK/3 TeV)2

F. Richard Feb 2003

K. Matchev (Arlington)

F. Richard Feb 2003

F. Richard Feb 2003

LH Scenario at LHC/FLC

‘A Higgs with mH> 300 GeV has been seen at LHC and nothing else’ (Bh and Zh too heavy)

‘LEP/SLD inconsistent with SM’

MSSM or standard Z’ cannot help

Within LH, GigaZ can predict the mass of Bh and tell if it can be reached at LHC with increased Luminosity

Synergy LHC-LC

F. Richard Feb 2003

UED Scenario

Scenario 1: ‘a light Higgs has been seen and nothing else’

No signal at FLC but GigaZ disagrees with SM (unclear with just LEP/SLD)

GigaZ can predict if KK observable at LHC

Synergy LHC-LC

Scenario 2: ‘a heavy Higgs has been seen and many indications of ‘SUSY’ particles’

Confusing/interesting situation FLC should see these particles and give

the correct interpretation

Complementarity LHC-LC

F. Richard Feb 2003

Conclusions

LEP/SLD data indicate that the gauge bosons predicted by the ‘Littlest Higgs’ model should be heavy

FT + LEP/SLD suggest that LH prefers a Higgs > 300 GeV

LHC will need full luminosity for direct observation of Bh

FLC can predict the mass of Bh and lower limits on Zh t’ masses

LEP/SLD data are also compatible with a heavy Higgs and UED

This scenario would result in a confused/exciting situation at LHC and would be ideal at FLC