1. Yasuhiro Okada (KEK) April 17, 2003, CAT, Indore, India
Physics at ACFA LC
Yasuhiro Okada (KEK)
April 17, 2003, CAT, Indore, India
April 17, 2003
CAT, Indore, India

2. Fundamental questions in elementary particle physics
What are the elementary
constituents of matter?
What are forces acting between them?
How did the Universe begin and evolve?
April 17, 2003
CAT, Indore, India

3. Our current understanding = The Standard Model of elementary particle physicsb t s c d u
quark nt t nm m ne e
lepton
Matter ：　
gauge force
Forces:
April 17, 2003
CAT, Indore, India

4. Developments of the Standard Model (SM)
quark
lepton
gauge principle
Higgs mechanism
(Mass generation)
u,d,s
e,m,n
photon
1970
“ Proposal of the Standard Model “
charm
(SPEAR,AGS)
t (SPEAR)
bottom
(FNAL)
gluon
(PETRA)
1980
W, Z bosons
( )
1990
gluon-coupling
(TRISTAN)
gauge-interaction
top
(TEVATRON)
(SLC, LEP)
2000
KM mechanism for
CP violation
(KEKB, PEP-II)
No experimental
confirmation
April 17, 2003
CAT, Indore, India

5. Quest for physics beyond the SM
Time
Energy
Temp.
SUSY GUT
Superstring
See-saw neutrino
Electroweak phase transition
Inflation
100 GeV
Strong int.
EM int.
Gravity
Planck energy
Weak int.
Unification
Supersymmetric grand unified theory, Superstring.
Neutrino mass
SuperKamokande, Cl,Ga, exp., K2K, SNO, KamLAND, …
Cosmology
Dark matter, Baryogenesis, Inflation,…
Need a higher energy
than 100 GeV.
April 17, 2003
CAT, Indore, India

6. Two types of accelerators: Electron-positron collider & Hadron machine
Discovery of new particles
J/y (charm), t, gluon
J/y (charm), b, W, Z, t
Establishment of new
mechanisms/principles
Gauge principle
CP violation
JLC
LHC (2007- )
Future machine
April 17, 2003
CAT, Indore, India

7. Worldwide consensus on construction of an electron-positron linear collider (LC)
A worldwide consensus in the high energy physics community has been reached to construct an electron-positron LC which can operate concurrently with CERN LHC.
Physics and experiments for LC with the center-of-mass energy of up to 500 GeV have been examined.
JLC-I (1992)
ACFA LC report (2001)
TESLA TDR (2001)
LC physics resource book for Snowmass 2001
April 17, 2003
CAT, Indore, India

8. Goals of JLC physics
Higgs physics ( Electroweak symmetry breaking and mass-generation)
Direct signals for new physics (SUSY, extra-dimensions, …)
Precision study on top and gauge bosons
“Unexpected” new signals
April 17, 2003
CAT, Indore, India

9. Higgs physics Higgs Field “Higgs boson”
Fills everywhere in the Universe.
Breaks the electroweak symmetry.
Provides masses to quarks,
leptons and gauge bosons.
A new particle is predicted.
Studio R
“Higgs boson”
April 17, 2003
CAT, Indore, India

10. Higgs boson search The Higgs boson: Not yet found experimentally.
114 GeV < Mh < 193 GeV (95%CL)
for the SM Higgs boson.
The Higgs hunting will be continued at TEVATRON and LHC.
TEVATRON Higgs search
LHC Higgs search
April 17, 2003
CAT, Indore, India

11. Luminosity = 500 /fb, Ecm=300 GeV
JLC = A Higgs factory
Higgs boson signal
Over 100,000 Higgs bosons can be
produced at JLC.
Luminosity = 500 /fb, Ecm=300 GeV
April 17, 2003
CAT, Indore, India

12. Higgs coupling measurements
Top Yukawa coupling
Higgs boson branching ratios
Coupling-mass relation
The Higgs vacuum-expectation-value
Particle mass
Higgs coupling constant
(Ecm >500 GeV) c b t
Mass-generation mechanism
April 17, 2003
CAT, Indore, India

13. Higgs potential = Origin of EW symmetry breaking
The first access to the Higgs potential
through double Higgs-boson production.
Need a higher energy for a precise
measurement of the self-coupling constant.
April 17, 2003
CAT, Indore, India
ACFA Higgs working group

14. More than one Higgs boson?
ACFA Higgs working group
Direct and indirect searches for heavy Higgs bosons at JLC.
April 17, 2003
CAT, Indore, India

15. Photon-photon collider
Laser
e- beam
a few mm g
JLC can have an additional interaction point with photon-photon collisions.
The heavy Higgs boson can be produced up to 400 GeV for 500 GeV LC. g
H/A
April 17, 2003
CAT, Indore, India

16. SUSY-partner particles
Supersymmetry (SUSY)
　SUSY
= Extension of the Einstein’s relativity
(Extension of space-time concept.)
SUSY-partner particles
Ordinary particle
Super-particle
W,Z,g,H
gluon
lepton
quark
neutralino,
chargino
gluino
slepton
squark
Studio R
April 17, 2003
CAT, Indore, India

17. SUSY particle search Smuon production and decay Dark matter candidate?
Smuon and neutralino masses are determined
to 1% or better.
April 17, 2003
CAT, Indore, India

18. Proving a new principle
Test of a SUSY relation
Test of the gaugino GUT relation
Selectron production
From selectron and chargino
productions
April 17, 2003
CAT, Indore, India

19. Determining SUSY breaking mechanism
LHC: Squark and gluino
production and cascade
decay
JLC: 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
April 17, 2003
CAT, Indore, India

20. Large extra-dimensions
Inspired by superstring theory,
a scenario with large extra-dimension is proposed.
graviton
quark, lepton,
gauge boson
Studio R
Quarks, leptons, and gauge bosons live in a 3-dimensional wall.
Gravity can propagate in 3+n dimensional space.
April 17, 2003
CAT, Indore, India

21. Search for extra-space at JLC
K.Odagiri
Graviton emission to extra-space
# of extra-dimensional space
The size and number of the extra-space may be determined at JLC.
April 17, 2003
CAT, Indore, India

22. Precision study on Top and W boson
Top quark threshold scan
Top: The heaviest particle discovered
so far.
Top production threshold scan
Precise determination of mass and width
Anomalous coupling measurements of
top and W boson production.
Physics beyond the SM
April 17, 2003
CAT, Indore, India

23. Detector of JLC The state-of-the-art detector
Very precise determination of
momentum and energy of
out-going particles
Heavy quark flavor tagging.
Identifying “invisible” particles.
Good timing resolution.
Much cleaner environment compared
to the LHC experiment.
April 17, 2003
CAT, Indore, India

24. Jet chamber test module
Detector R&D for JLC
Jet chamber test module
Vertex detector test module
12 ton test module of the calorimeter
Present Framework; ACFA working group.
(Work by 15 institutes of Japan, Korea and the Philippines)
Collaboration with Europe is developing (UK, Germany, Russia)
Collaboration with North America, under discussion.
April 17, 2003
CAT, Indore, India

25. Summary of physics goals
Higgs physics Determination of Higgs couplings Origin of masses Higgs potential Dynamics of the electroweak symmetry breaking.
Direct signals for new physics Discovery of SUSY or extra-dimensions Change of the space-time concept.
Precision study on top and gauge bosons Measurements of basic parameters of physics.
“Unexpected” new signals Advantage of an energy-frontier electron-positron collider.
April 17, 2003
CAT, Indore, India

26. Concurrent operation of JLC and LHC
Establishing
new principles
Particle discovery
Higgs boson
mass-generation
mechanism
Spin/parity
Coupling measurements
Higgs self-coupling
LHC
JLC
Higgs physics
TEVATRON
Squark/gluino
cascade decays
Slepton/chargino/
neutralino
JLC
SUSY breaking
mechanism
Proof of SUSY
LHC
Supersymmetry
spin/coupling
measurements
TEVATRON
April 17, 2003
CAT, Indore, India

27. Physics research covered by JLC
1st stage: Ecm = GeV, Luminosity = ~ 200/fb x several years .
2nd stage: Ecm = 1 TeV or more.
April 17, 2003
CAT, Indore, India

28. Conclusions
Goals of research at JLC are to open a new era of elementary particle physics through critical discoveries which lead to new fundamental principles of Nature.
(Origin of mass, new concept on space-time structure, vacuum structure of the Universe, etc.)
Rich physics programs are expected for the first stage of the JLC experiment with the center-of-mass energy of up to 500 GeV.
Energy upgrade to 1TeV or more is important.
April 17, 2003
CAT, Indore, India