The Nobel Prize in Physics 2008 Kobayashi Maskawa
The Nobel Prize in Physics 2008: Kobayashi & Maskawa A. Pich IFIC, Valencia To the memory of our friend PACO
l C , P: interactions Violated maximally in weak l CP : Symmetry of nearly all observed phenomena l Slight (~ 0. 2 %) CP l Sizeable CP in in decays (2001) l Huge Matter Antimatter Asymmetry in our Universe Baryogenesis CP CPT Theorem: T Thus, CP requires: § Complex Phases § Interferences (1964)
Scientific Context • Z. Maki, M. Nakagawa, S. Sakata, PTP 28 (1962) 870 • N. Cabibbo, PRL 10 (1963) • S. L. Glashow, J. Iliopoulos, L. Maiani, PRD 2 (1970) • M. K. Gaillard, B. W. Lee, PRD 10 (1974) 897 • J. J. Aubert et al. , PRL 33 (1974) 1404 • J. E. Augustin et al. , PRL 33 (1974) 1406 n m , UL q. C GIM mc J/y
Quartet Model q Pre-Quark Quartet Model • Triplet Model: (p, n, L) Sakata 1956 • Lepton-Baryon symmetry: (n, e, m) • (ne, nm, e, m) (p, p’, n, L) Gamba-Marshak-Okubo 1959 Kyoto / Nagoya groups 1962 q Quark Quartet Model • Quark-Ace Triplet: (p, n, L) • Quark Quartet: (p, n, l, p’) , Charm Gell-Mann, Zweig 1964 Glashow-Iliopoulos-Maiani 1970 q Japanesse Cosmic Ray Events • X± x± p 0 (1 evt) , MX≈1. 8 -3 Ge. V , t. X ≈ 10 -14 s Niu-Mikumo-Maeda 1971 • Further events (1973 – 1975) from cosmic rays and proton beams • Interpretation of X± as a p’ flavoured hadron Hayashi et al
Starting Points q Weinberg’s EW model for leptons: • SU(2)weak U(1) gauge group • Doublet scalar field q Quartet field: j = (j+, j 0) q = (p , n , z , l) • Electromagnetic charges (Q, Q-1, Q, Q-1) q Hadronic chiral SU(4)L SU(4)R invariance q Possible SU(2)weak assignments for q. L, R: A: 4 = 2+2 ; B: 4 = 2+1+1 ; C: 4 = 1+1+1+1
Possible SU(2)weak assignments for q. L, R: A: 4 = 2+2 ; q 9 possibilities: B: 4 = 2+1+1 ; C: 4 = 1+1+1+1 (q. L, q. R) = (A, A) , (A, B) , (A, C), . . . q All q components should have weak interactions. FCNC bounds (B, C) , (C, B) , (C, C) excluded q (B, A) and (C, A) “equivalent” to (A, B) and (A, C) (up to relative signs between vector and axial currents) (A, A) , (A, B) , (A, C) , (B, B)
(q. L = 2+2 , q. R = 1+1+1+1) SM SSB Charged-current interactions (2 SM generations)
q (2+2 , 2+1+1) , (2+1+1 , 2+1+1) • CP violation possible • Conflicting constraints from FCNC , mz mp, n, l and baryon octet g. A / g. V q (2+2 , 2+2) • No CP violation • Reduces to an exactly U(4) symmetric model
CP violation requires new fields [ (2+2 , 1+1+1+1) only ] q Model 1: Two scalar doublets q Model 2: scalar SU(4)L SU(4)R field, which mediates the strong interaction and interacts with j q Model 3: 6 -plet model (Q, Q-1; Q, Q-1) (q. L = 2+2+2 , q. R = 1+1+1+1)
(q. L = 2+2+2 , q. R = 1+1+1+1)
Unitarity Triangle
N L MIXING Maki-Nakagawa-Sakata 1962
Cabibbo 1963 N L MIXING
To the memory of our friend PACO
FERMION GENERATIONS Identical Copies Masses are the only difference WHY ? SSB Arbitrary Non-Diagonal Complex Mass Matrices
DIAGONALIZATION OF MASS MATRICES Mass Eigenstates Weak Eigenstates QUARK MIXING
Flavour Conserving Neutral Currents Flavour Changing Charged Currents u d c s t b
QUARK MIXING MATRIX l Unitary l Matrix: parameters arbitrary phases: Physical Parameters: Moduli ; phases
● Nf = 2 : 1 angle, 0 phases (Cabibbo) ● Nf = 3 : 3 angles, 1 phase (CKM)
Unitarity Triangle
FERMION MASSESS Scalar – Fermion Couplings allowed by Gauge Symmetry SSB Fermion Masses are New Free Parameters Couplings Fixed:
LEPTON MIXING l IF Separate Lepton Number Conservation l IF BUT
Standard Model Parameters QCD: 1 EW Gauge / Scalar Sector: 4 Yukawa Sector: 13 18 Free Parameters TOO (+ Neutrino Masses / Mixings ? ) MANY !
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