1. Higgs and SUSY at future colliders
Yasuhiro Okada (KEK)
Hiroshima Univ. January 17, 2006

2. Why TeV?, Why New Physics?
LHC will start in the next year, which will explore TeV scale physics.
Main objectives are Higgs physics and search for New physics.
These two are closely related because the dynamics behind the electroweak symmetry breaking is “New Physics”.

3. Other reasons to believe physics beyond the Standard Model
Neutrino masses
Dark Matter
Baryon number in the Universe.
Solutions to these questions may or may not
lie in the TeV region.

4. Contents of this talk (1) Higgs Physics (2) Supersymmetry
(3) Dark Matter and collider physics.

5. (1) Higgs Physics
Finding the mass-generation mechanism for gauge bosons, quarks and leptons the most urgent question of the present particle physics.
Discovery of the Higgs boson is the first step
(1) Discovery of a Higgs boson
(2) Higgs coupling measurements.
(3) Physics behind the EW symmetry breaking

6. Higgs mass Large Higgs mass  Large self-coupling  Strong dynamics
If we require that the SM is valid
up to 10^19 GeV,

7. Higgs mass in SUSY models
SUSY models include at least two Higgs doublets.
In the minimal SUSY Standard Model (MSSM), the lightest CP-even Higgs boson mass has theoretical upper bound.
Possible vacuum instability is saved by supersymmetry.

8. Possible range of the lightest Higgs boson mass for the Planck scale cutoff
As long as theory behaves weakly-coupled up to the Planck scale,
the Higgs bosom mass is les than ~200 geV.

9. Precision EW test and the Higgs Mass
In the SM, the global fit suggests a light Higgs boson.
M.Peskin and J.Wells
mt= GeV
mh=100,200,300,500,1000 GeV
Additional new physics is needed
to accommodate a heavy Higgs boson.

10. Higgs search at LHC LHC： 2007 14 TeV pp collider
Discovery of the Higgs boson is a main target.
Higgs boson search depends on the Higgs boson mass
Production:　gluon fusion, WW fusion
Decay: decay to heavier particles if kinematically allowed. p p Ｗ
gluon
Higgs boson
Higgs boson Ｗ p
gluon p

11. SM Higgs boson decay branching ratios
Higgs discovery at ATLAS
At LHC, a SM-like Higgs boson can be
discovered independent of its mass.

12. ILC (International Linear Collider)
Highest energy e^+e^- collider
　　500 GeV (1st stage) -> ~ 1 TeV (2nd stage)
High luminosity, 10^34/cm^2/s　
　　　(~10^5 light Higgs boson =Higgs factory
Startin mid-2010’s　

13. Higgs physics at ILC Determination of spin and parity.
Precise mass determination .
Detection of the Higgs boson independent of its decay property. (Recoil mass distribution in the HZ mode)
Coupling measurement
-> Mass generation mechanism of elementary particles.
TESLA TDR
GLC report

14. Higgs coupling LHC 0(10)% for ratio of the coupling constants ILC
A few % for absolute values
of various coupling

15. Indirect constraint on the heavy Higgs boson mass in MSSM
Direct search
at LHC
Direct search
at 1TeV LC
ACFA Higgs WG
S. Kiyoura, et al
ACFA report

16. SUSY loop contributions to the hbb Yukawa coupling
B(h->bb)/B(h->tt) is sensitive to
the SUSY loop correction to the
bottom Yukawa coupling for a
large tanb region.
B(h->bb)/B(h->tt) nomalized by SM value LC
LHC
K.S.Babu, C.Kolda:
M.Carena, D.Garcia, U.Nierste, C.E.M.Wagner
J.Guasch, W.Hollik,S.Penaranda

17. Higgs self-coupling measurement
Access to the Higgs potential.
Precision at 1/ab for 120 GeV Higgs boson
~20% for 500GeV ILC
~10% for 1 TeV ILC
Y.Yasui, et al, LCWS 02

18. Electroweak baryogenesis and Higgs potential
First order phase transition
Extension of the Higgs sector
The Higgs potential at zero temperature is also modified.
=> Self coupling measurement
Model with dim 6 potential
2HDM
S.Kaenmura, Y. Okada, E.Senaha
C.Grojean,G.Servant, J.D.Wells

19. Higgs and physics beyond the SM
Even if one Higgs doublet model is a good description,
What is f?
What physics determines –m^2?
What physics determines l?
Different scenarios provides different answers.
SUSY, String Theory
Composite model, Little Higgs model
TeV scale extra dimension

20. Composite model
~10 TeV a
SUSY GUT
Gravity
Gauge force
Extra dimension
Various new physics signals
are expected in the TeV
region, depending on different
signals.

21. (2) Supersymmetry Symmetry between bosons and fermions
Discovery of SUSY is a revolution of physics similar to relativity. (extension of relativity, generalization of the space-time concept)
A solution to the hierarchy problem.
The coupling unification in SUSY GUT

22. Hierarchy problem and SUSY
String and GUT unification -> A cutoff scale ~ Planck scale (10^19 GeV).
SUSY is the only known symmetry to avoid the fine tuning in the renormalization
of the Higgs boson mass at the level of O(10^34).
Three possibilities:
Some new dynamics associated with the electroweak symmetry breaking exists just above the TeV scale.
SUSY exists.
Fine-tuning is realized by unknown reason.
=> LHC will provide a hint on which is the correct direction.

23. SUSY models
A SUSY model is not a single model, rather collection of models.
The number of free parameters of the minimal supersymmetric standard
model (MSSM) is about 100.
Low energy SUSY models = SUSY extensions of the SM
R-parity conserving
model
R-parity violation
MSSM
NMSSM,
Extra U(1),
etc.
SUSY Breaking scenarios
(mSUGRA, AMSB,
GMSB, etc.)
SUSY GUT, See-saw neutrino, String unification
No strong motivations to consider beyond the MSSM.

24. MSSM
The particle content of MSSM = Two Higgs doublet SM + scalar SUSY partners
and fermionic SUSY partners
Two Higgs doublets are necessary for fermion Yukawa couplings.
H1: down-type-quark and lepton Yukawa couplings
H2: up-type-quark Yukawa couplings

25. ＳＵＳＹ phenomenology Discover SUSY particles
Establish the symmetry property.
Determine SUSY breaking mechanism.
Clarify the meaning in unification and the cosmological connection.

26. SUSY at LHC LHC experiments will provide a crucial test for SUSY.
Mass reach of squark and gluino search is about 2 TeV.
A light Higgs boson below 135 GeV must exist for MSSM.
Higgs search:
At least one Higgs boson can be found.
SUSY search: Cascade decay.
~gluino
2 TeV
m1/2(GeV)
mSUGRA
MSSM

27. LC studies on SUSY
Determine mass, spin and quantum numbers of SUSY particles. Beam polarization and energy scan are very useful tools.
Determine chargino and neutralino mixings.
Test SUSY coupling relations.
Test the gaugino GUT relation.
Determine properties of the dark matter candidate.
Search for lepton flavor violation in slepton production and decays.

28. Smuon production and decay
Test of a SUSY relation
Smuon production and decay　
Selectron production
Dark matter candidate?
M.M.Nojiri, K. Fujii and T. Tsukamoto

29. SUSY breaking scenario
Combined analysis of LHC and LC provide a hint on
a SUSY breaking scenario.
LHC: Squark and gluino
production and cascade
decay
LC: Slepton, neutlarino, and
chargino pair-production
SUSY particle masses
Combined analysis
Energy scale
SUSY breaking scenario
G.A.Blair, W.Porod,and P.M.Zerwas

30. SUSY Seesaw model
Large Lepton flavor violation processes are expected.
m->eg in SU(5) SUSY GUT
with seesaw neutrino
Slepton flavor mixing
J.Hisano, M.M.Nojiri, Y.Shimizu, M.Tanaka
MEG experiment
T.Goto,Y.Shimizu,T.Shindo,M.Tanaka and Y.Okada.

31. (3) Dark matter and collider physics
Energy composition of the Universe
Dark energy 73%
　 Dark matter 23%
　 Baryon　　　　　4%
Dark matter candidate
WINP （weakly interacting massive particle)
　Stable, neutral

32. Relic abundance of dark matter
A larger pair annihilation cross section
-> Smaller relic abundance
Candidates of dark matter
　 SUSY neutralino, gravitino
　 KK-photon in the universal extra dimension model,
Heavy photon in the little Higgs model with a T parity
Collider physics
(1) Discovery of the dark matter candidate
(2) Identify a correct model.
(3) Determine the mass and couplings and compare the relic abundance.

33. Identification of the dark matter at LC
　Even if a dark matter candidate is found at LHC by missing energy signals,
many possibilities can exist. Ex. SUSY and KK model can be distinguished
at LC.
Threshold behaviors for smuon and
KK muon productions
neutralino
sneutrino
KK photon
M.Peskin

34. SUSY Dark matter at LC SUSY mass and coupling measurements
ALCPG cosmology subgroup
SUSY mass and coupling measurements
=> Identification of dark matter
PLANCK
WMAP

35. Conclusions
Discovery of the Higgs boson is the first step to understand the dynamics of the electroweak symmetry breaking.
In order to confirm the mass generation mechanism of elementary particles, coupling constants related to the Higgs boson have to be measured precisely.
SUSY, if it exists, has far-reaching consequences in particle physics and cosmology.