CP Violation and Flavor Mixing Makoto Kobayashi KEK and JSPS Plan

1. Introduction to the Standard Model 2. Sakata and His Group 3. The CP Paper with Maskawa 4. Experimental Verification at B-factories 5. Lepton Flavor Mixing Introduction to the Standard Model

u d u Electron p Proton（p）

n

Nucleus d d u Atom Neutron（n） Introduction to the Standard Model

Fundamental Particles u c t Quark d s b

e μτ Lepton

νe νμ ντ

Fundamental Interactions

• Strong Interaction QCD • Electro‐Magnetic Interaction • Weak Interaction Weinberg‐Salam‐Glashow Theory Introduction to the Standard Model

Established in 1970’s ・ Development of gauge theory 1971 ‘t Hooft Electro‐Magnetic Interaction Strong Interaction Weak Interaction ・ Discoveries of new flavors u c t 1964 Gell‐Mann quark model d s b u, d, s

e μτ 1973 Kobayashi Maskawa

νe νμ ντ Six‐Quark Model

After 1970 Sakata and His Group

1947∼ Discovery of Strange Particles

Hadron : strongly interacting particle np π±0 Λ

±0 ΞΣΛ ± KK 0 Λ Courtesy of Sakata Memorial Archival Library Strange Particles Shoichi Sakata 1911-1970 1956 Sakata Sakata Model

All the hadrons are composite states of np ,, Λ : Fundamental Triplet Sakata and His Group

Weak Interaction in the Sakata Model

β decay- epn − ++→ ν paticle strange paticle Λ ep − ++→ ν

p ν

n Λ e μ

1959 Gamba, Marshak, Okubo B‐L Symmetry 1960 Maki, Nakagawa, Ohnuki, Sakata Nagoya Model : +ν + ,, =Λ== BeBnBp +μ Sakata and His Group

1962 Discovery of Two Neutrinos

ν e ν μ Lepton Flavor Mixing e μ MNS Matrix 1962 Maki, Nakagawa, Sakata + + + + p = B ν1 , n = B e , Λ = B μ , p'= B ν 2

ν1 = cosθ ν e + sinθ ν μ

ν 2 = −sinθ ν e + cosθ ν μ

Neutrino Oscillation 4th Fundametal Particle (GIM scheme) 1962 Katayama, Matumoto, Tanaka, Yamada Sakata and His Group

Cosmic Ray Events

1971 Niu et al. Evidence for the 4th element?

Some Japanese groups began to investigate the four-quark model

Emulsion Technique • Applied to accelerator exp. • Life time measurement of the new flavors CP Paper with Maskawa

1971 ‘t Hooft : Renormalization of Non-Abelian gauge theory Renormalizable Electro-Weak Theory (Weinberg-Salam-Glashow ) CP Violation 1964 Cronin et al. 1973 Kobayashi, Maskawa K L → ππ Essential difference How to accommodate CP violation between particles and anti-particles

What we found • Not possible in four-quark models • Existence of unknown particles • A possible candidate is six-quark model CP Paper with Maskawa

Flavor Mixing

Mismatch between gauge symmetry and particle spectra

⎛u ⎞ ⎛c ⎞ ⎛d′⎞ ⎛ VV ⎞ ⎛d ⎞ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ = ⎜ usud ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ′ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝d′⎠ ⎝ s′⎠ ⎝ s ⎠ ⎝ VV cscd ⎠ ⎝ s ⎠

CP Violation

Complex elements not removable by the phase convention

⎛e −iδu 0 ⎞⎛ VV ⎞⎛e iδd 0 ⎞ ⎛ − sincos θθ ⎞ ⎜ ⎟⎜ usud ⎟⎜ ⎟ = ⎜ ⎟ ⎜ −iδc ⎟⎜ ⎟⎜ iδ s ⎟ ⎜ ⎟ ⎝ 0 e ⎠⎝ VV cscd ⎠⎝ 0 e ⎠ ⎝ cossin θθ ⎠ CP Paper with Maskawa

6-Quark Model ⎛d′⎞ ⎛ VVV ⎞ ⎛d ⎞ ⎛u ⎞ ⎛c ⎞ ⎛t ⎞ ⎜ ⎟ ⎜ ubusud ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ′ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ s ⎟ = ⎜ VVV cbcscd ⎟ ⎜ s ⎟ ⎝d′⎠ ⎝ s′⎠ ⎝b′⎠ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝b′ ⎠ ⎝ VVV tbtstd ⎠ ⎝b ⎠

VVV ⎛ − λ2 21 3 ( − iA ηρλλ)⎞ ⎛ ubusud ⎞ ⎜ ⎟ ⎜ VVV ⎟ ≈ − λ − λ2 21 Aλ2 ⎜ cbcscd ⎟ ⎜ ⎟ ⎜ VVV ⎟ ⎜ 3 2 ⎟ ⎝ tbtstd ⎠ ⎝ A ()1 −−− Ai ληρλ1 ⎠

• An imaginary number parameter violates CP CP Paper with Maskawa

• 1974 Discovery of J/ψ c-quark • 1975 Discovery of τ -lepton

1975 S. Pakvasa, H. Sugawara 1976 J.R Ellis, M-K Gaillard, D. Nanopoulos

• 1977 Discovery of Υ b-quark • 1995 Discovery of t-quark Large CP violation in the B-meson system

1980 Carter, Sanda Bd : db Bd : bd 1981 Bigi, Sanda

B : B-Factory u ub Bu: bu

B-Mesons E(e−)=8GeV, E(e−)=9GeV, E(e+)=3.5GeV Feature E(e+)=3.1GeV Finite angle beam crossing Zero angle beam crossing 1994 1993

May 1999 – May 1999 – still running Apr. 2008

L = 1.7×1034/cm2/s Friendly competition of two peak experiments over a decade

34 2 Lpeak = 1.2×10 /cm /s PeP-II BaBar Belle: 14 countries, 59 institutes, about 400 researchers Experimental Verification at B-Factories Experimental Verification at B-Factories

Present Status of CP Violation

B-factory results show that quark mixing is the dominant source of CP violation

B-factory results allow room for additional source from new physics

Matter dominance of the Universe seems requiring new source of CP violation Lepton Flavor Mixing

Discovery of neutrino oscillation at Super-Kamiokande using atmospheric neutrinos

Atmospheric Neutrino Multi-GeV μ-like + PC Super-K 1996～ θ

Earth ν

C.R. Courtesy of KEK Yoji Totsuka 1942-2008 J.Raaf, Talk at Neutrino 2008 Lepton Flavor Mixing

K2K experiment KamLAND experiment

νμ : KEK-PS νe： reactor fit_out.0x03.cmb.free.1.shape 18

] Entries 58 GeV

[ 16 1R-μ spectrum 14 events/0.25 12

10 No oscillation

8 Oscillation

6

4 Number of events

2

0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 [GeV] 1 234Eνrec

νμ disapearance νe disapearance Lepton Flavor Mixing

T2K experiment

νμ created at JPARC Super-K

Aiming to discover

νe appearance