1. A. Bay Beijing October 20051 Summary 1. Some history 2. Antiparticles 3. Standard Model of Particles (SM) Discrete symmetries, CP violation, Connection with Cosmology Fermionic mass generation mechanism, Why do we think that the SM is not the final word ?

2. A. Bay Beijing October 20052 The Standard Model e   e      u c t d s b Quarks Strong : gluons E.M. : photon Weak : W + W  Z INTERACTIONSMATTER e.m. charge [e] 0  1 2/3  1/3 The SM incorporates: QED: photon exchange between charged particles Weak (Flavour-Dynamics): exchange of W  and Z QCD: gluon exchange between quarks do not forget antiparticles... ! Spin 1/2 Spin 1

3. A. Bay Beijing October 20053 Discrete symmetries Parity: left Charge particle antiparticle conjugation Temporal inversion right

4. A. Bay Beijing October 20054 symmetry violation... suddenly we discover that we can observe a "non - observable". A is discovered. Some symmetries might have a deep reason to exist... other not. The Right-Left symmetry (Parity) was considered an exact symmetry  1956

5. A. Bay Beijing October 20055 Discrete symmetries P and C e.m. interactions are P & C invariant P: (x,y,z) -> (-x,-y,-z). C: charge ->  charge. angular momentum, spin.

6. A. Bay Beijing October 20056 What about T ? If x(t) is solution of F = m d 2 x/dt 2 then x(-t) is also a solution (ex.: billiard balls) Ok with electrodynamics:

7. A. Bay Beijing October 20057 Parity: (x,y,z)  (-x,-y,-z) 1848 L. Pasteur discovers the property of optical isomerism. The synthesis of the lactic acid in the lab gives a "racemic" mixture: N left molecules = N right molecules (within statistic fluctuations) This reflects the fact that e.m. interaction is M (and P) invariant Mirror symmetry Asymmetry =

8. A. Bay Beijing October 20058 Parity violation in biology Humans are mostly right handed: Asymmetry  A = (N R  N L )/(N R +N L ) ≈ 0.9  “90% Parity violation" snif Lemmon and orange flavours are produced by the two "enantiomers" of the same molecule.

9. A. Bay Beijing October 20059 100% P violation in DNA

10. A. Bay Beijing October 200510 Too much symmetry... LLRR LR

11. A. Bay Beijing October 200511 Partial R-L symmetry in Rome MUSEE ROMAIN DE NYON ? Bacchus, Arianna ?

12. A. Bay Beijing October 200512 Some asymmetry introduces more dynamics

13. A. Bay Beijing October 200513 P conserved in e.m. and strong interacctions 1924 O. Laporte classified the wavefunctions of an atom as either even or odd, parity  or . In e.m. atomic transitions a photon of parity  is emitted. The atomic wavefunction must change to keep the overall symmetry constant (Eugene Wigner, 1927) : Parity is conserved in e.m. transitions This is also true for e.m. nuclear or sub-nuclear processes (within uncertainties). H(strong) and H(e.m.) are considered parity conserving.

14. A. Bay Beijing October 200514 Parity in weak interactions * E. Fermi, 1949 model of W interactions: P conservation assumed * C.F. Powell,... observation of two apparently identical particles "tau" and "theta" weakly decaying tau  3 pions theta  2 pions which indicates P(tau) =  and P(theta) =  If Parity holds "tau" and "theta" cannot be the same particle. * HEP conf. Rochester 1956 Tsung Dao Lee and Chen Ning Yang suggest that some particles can appear as parity doublets. Feynman brought up the question of non-conservation of parity (but bets 50 $ that P is conserved). Wigner suggests P is violated in weak interactions.

15. A. Bay Beijing October 200515 Parity in weak interactions.2 Lee and Yang make a careful study of all known experiments involving weak interactions. They conclude "Past experiments on the weak interactions had actually no bearing on the question of parity conservation" Question of Parity Conservation in Weak Interactions T. D. Lee Columbia University, New York, New York C. N. Yang Brookhaven National Laboratory, Upton, New York The question of parity conservation in beta decays and in hyperon and meson decays is examined. Possible experiments are suggested which might test parity conservation in these interactions. Phys. Rev. 104, 254–258 (1956)

16. A. Bay Beijing October 200516 Co 60 1956 C. S. Wu et al. execute one of the experiments proposed by Lee and Yang. Observables: a "vector" : momentum p of beta particles an "axial-vector" : spin J of nucleus (from B). Compute m = In a P reversed Word: P: Jp   Jp P symmetry implies m = 0 Co60 at 0.01 K in a B field. m was found  0  P is violated Co Jp p J

17. A. Bay Beijing October 200517 152 Sm Polarimeter: selects  of defined helicity 152 Sm  NaI Counter Result: neutrinos are only left-handed Measurement of neutrino helicity (Goldhaber et al. 1958)

18. A. Bay Beijing October 200518 Parity P and neutrino helicity right left P P symmetry violated at (N L  N R )/(N L  N R ) = 100%

19. A. Bay Beijing October 200519 Charge conjugation C left C left  C symmetry violated at 100% C transforms particles  antiparticle

20. A. Bay Beijing October 200520 CP Last chance: combine C and P ! left right Is our Universe CP symmetric ?

21. A. Bay Beijing October 200521 (A)symmetry in the Universe matter antimatter Big Bang produced an equal amount of matter and antimatter Today: we live in a matter dominated Universe time Big Bang

22. A. Bay Beijing October 200522 Baryo genesis Big Bang models are matter/antimatter symmetric Where is ANTIMATTER today? 1) Anti-Hydrogen has been produced at CERN: antimatter can exist. 2) Moon is made with matter. Idem for the Sun and all the planets. 3) In cosmics we observe e + and antiprotons, but rate is compatible with secondary production. 4) No sign of significant of e + e  annihilation in Local Cluster. 5) Assuming Big Bang models OK, statistical fluctuations cannot be invoked to justify observations. No known mechanism to separate matter and antimatter at very large scale in the Univers ! e + e  annihilation in the Galaxy

23. A. Bay Beijing October 200523 sensitivity (0.5 - 20 GeV): He/He ~10  C/C ~10  AMS

24. A. Bay Beijing October 200524 Baryogenesis.2 Today (age of Univers 10-20 10 9 years): no significant amount of antimatter has been observed. The visible Universe is maid of protons, electrons and photons The N of photons is very large compared to p and e  matter =0.1  C =1 10 -6 GeV/cm 3  10 -6 p/cm 3 N protons N photons     

25. A. Bay Beijing October 200525 Baryogenesis.3 N   ( )  412 photons/cm 3 3 kT cc 2  2 This suggests a Big Bang annihilation phase in which matter + antimatter was transformed into photons... Sky T observed by COBE~ 2.7K

26. A. Bay Beijing October 200526 Baryogenesis.4

27. A. Bay Beijing October 200527 Baryo genesis.5 1)  processes which violate baryonic number conservation: B violation is unavoidable in GUT. 2) Interactions must violate C and CP. C violated in Weak Interactions. CP violation observed in K and B decays. 3) System must be out of thermal equilibrium Universe expands (but was the change fast enough ?) Starting from a perfectly symmetric Universe: 3 rules to induce asymmetry during evolution Andrej Sakarov 1967 B(t=0) = 0 B(today)>0

28. A. Bay Beijing October 200528 Baryogenesis.6 Prob(X  qq) =  Prob(X  qe - ) = (1  - - - Prob(X  qq) =  Prob(X  qe + ) = (1  - Requirement:  q ou q e + q ou q e  X X 10 27 °K... forbidden by CP symmetry !  { X  qq - - - X  qq CP mirror

29. A. Bay Beijing October 200529 CP violation K 0 L    e      e   MIRROR CP { CP symmetry implies identical rates. Instead... K 0 L is its own antiparticle K 0 L S. Bennet, D. Nygren, H. Saal, J. Steinberg, J. Sunderland (1967): July 1964: J. H. Christenson, J. W. Cronin, V. L. Fitch et R. Turlay find a small CP violation with K 0 mesons !!!    e   N    e   N     e   N    e   N +    % provides an absolute definition of + charge

30. A. Bay Beijing October 200530 CP violation experiment

31. A. Bay Beijing October 200531 K0K0 K0K0 Processes should be identical but CPLear finds that neutral kaon decay time distribution  anti-neutral kaon decay time distribution CPLear Other experiments: NA48, KTeV, KLOE  factory in Frascati,...

32. A. Bay Beijing October 200532 NA48 decay channel The Kaon decay channel of the NA48 experiment at CERN - the latest study to provide a precision measurement of CP violation.

33. A. Bay Beijing October 200533 CPT Schwinger-Lüders-Pauli show in the '50 that a theory with locality, Lorentz invariance spins-statistics is also CPT invariant. Consequences: * Consider particle  at rest. Its mass is related to:  particle and antiparticle have same mass (and also same life time, charge and magnetic moment) * If a system violates CP  T must be violated,...

34. A. Bay Beijing October 200534 0 T from CPLear (6.6  1.6)10  oscillations s d K0K0 K0K0 s d t t WW

35. A. Bay Beijing October 200535 Electric Dipole Moments Energy shift for a particle with EDM d in a weak electric field E is linear in E:  E = E d. d can be calculated from d =  r i q i which is left unchanged by T: q  q T: r  r Consider a neutron at rest. The only vector which characterize the neutron is its spin J. If a non-zero EDM exists in the neutron: d = k J Under time reversal T: J   J This implies k = 0 if T is a good symmetry:  d = 0

36. A. Bay Beijing October 200536 E D M 2 expt [e cm]SM prediction proton(  4  6 ) 10  10  neutron< 0.63 10  ( 95% CL) 10  electron( 0.07  0.07 ) 10  10  muon( 3.7  3.4 ) 10  10  129-Xe<10  27 199-Hg<10  28 muon measurement in future "neutrino factories"  10  No signal of T violation "beyond the Standard Model" so far !

37. A. Bay Beijing October 200537 CP & T violation only in K 0 system ??? Since 1964, CP and or T violation was searched for in other systems than K 0, other particles decays, EDM... No other signal until 2001. In 2001 Babar at SLAC and Belle at KEK observe a large CP vioaltion in the B0-B0bar system

38. A. Bay Beijing October 200538 Origin of CP violation Hamiltonian H = H 0 + H CP with H CP responsible for CP violation. Let's take H CP = gH + g*H † where g is some coupling. The second term is required by hermiticity. If under CP: H  H † that is CP H CP † = H † then CP H CP CP † = CP (gH + g*H † ) CP † = gH † + g*H CP invariance : H CP = CP H CP CP †  gH + g*H † = gH † + g*H The conclusion is that CP is violated if g  g* i.e. g non real CP violation is associated to the existence of phases in the hamiltonian.

39. A. Bay Beijing October 200539 II III I CP violation and SM SM with 3 families can accommodate CP violation in the weak interactions through the complex Cabibbo-Kobayashi-Maskawa quark mixing matrix V CKM, with 4 parameters. uctuct dsbdsb Up type quark spinor field Q =  Down type quark spinor field Q =  SM does not predict these parameters...

40. A. Bay Beijing October 200540 In the '60... Parameters V ij are used to calculate the transitions quark(i)  quark(j) first introduced by N. Cabibbo for i,j=u, d, s V Cabibbo is real, while CPV implies that some of the V ij  complex ! s u W VusVus V Cabibbo = The quark c was introduced in 1970 (GIM), discovered in 1974.  cabibbo ~ 12° In the 1970 the "flavour mixing" matrix was

41. A. Bay Beijing October 200541 CKM matrix CPV implies that some of the V ij  complex. In 1972 Kobayashi & Maskawa show that, in order to generate CP violation (i.e. to get a complex phase), V must be (at least) 3x3  this is a prediction of the three quark families of the SM: (u, d), (c, s), (t, b) V CKM = In the SM, with 3 and only 3 families of quarks, the matrix must be unitary The last quark, t, was observed 25 years later !

42. A. Bay Beijing October 200542 CKM matrix in the SM L = L W,Z + L H + L Fermions + L interaction L Fermions contains the (Yukawa) mass terms: M U and M D complex matrices, diagonalized by a couple of non-singular matrices, to get the physical mass values:

43. A. Bay Beijing October 200543 CKM matrix.2 After the transformation (idem for D quarks) e.m. and neutral currents unaffected. The charged currents are modified: "mixing matrix" V unitary s u W VusVus

44. A. Bay Beijing October 200544 CKM matrix.3 downstrange beauty up 0.97 0.22 0.002 charm 0.22 0.97 0.03 top 0.004 0.03 1 + O( 4 ) = sin(  Cabibbo ) =0.224 A=0.83±0.02 phase: change sign under CP parametrized by 4 real numbers (not predicted by the SM). Need to measure them. Magnitude ~ Wolfestein (1983)

45. A. Bay Beijing October 200545 CKM matrix.4 downstrange beauty up 0.1% 1% 17% charm 7% 15% 5% top 20% ?% 29%  V ij  )/  V ij  ~ Today precision from direct measurements, no unitarity imposed:

46. A. Bay Beijing October 200546 CKM matrix.5 + O( 4 ) downstrange beauty up 0 0 115° charm 0 0 0 top 25° 0 0 Phase ~ downstrange beauty up 0 0  115° charm 0 0 0 top  25° 0 0 Wolfestein (1983)

47. A. Bay Beijing October 200547 CKM Matrix and the Unitary Triangle(s) SM  Unitarity V ji *V jk =  ik  V ud V ub  + V cd V cb  + V td V tb  = 0 V ud V ub V td V tb * V cd V cb * *          The Unitary Triangle Triangle Re Im

48. A. Bay Beijing October 200548          Re Im  1  CKM Matrix and the Unitary Triangle(s).2 + O( 4 ) SM  Unitarity V ji *V jk =  ik  V ud V ub  + V cd V cb  + V td V tb  = 0 The Unitary Triangle Triangle after normalization by V cd V cb *=A 3

49. A. Bay Beijing October 200549 Experimental program: measure sides and angles * CP violated in the SM => the area of triangle  0 * Any inconsistency could be a signal of the existence of phenomena not included in the SM    ~V ub ~V td ~V cb Use B mesons phenomenology t quark oscillations CP asymmetries b quark decays

50. A. Bay Beijing October 200550 Why do we expect some NEW PHYSICS ? * SM has 18 free parameters (more with massive neutrini), in particular masses and CKM parameters are free. * Some of the neutrinos have masses>0 * Why the electric charge is quantized ? * The choice of SU(2)U(1) is arbitrary. * Gravitation is absent. * Problems in Cosmology: What is the nature of dark matter and dark energy ? Baryogenesis does not work in the SM: The SM amount of CP violation is too low The requirement of non-equilibrium cannot be obtained with heavy Higgs => new light scalar must exist

51. A. Bay Beijing October 200551 Cosmics

52. A. Bay Beijing October 200552 masses & mixings In the SM, CPV is related to the mass generation mechanism for the fermions. The fermionic system is far from being understood. Is there any "periodicity" in the mass spectrum? Similar question for the mixing matrices.

53. A. Bay Beijing October 200553 Any horizontal symmetry ? CPV, mix., baryogenesis: hep-ph/0108216v2 * Neutrino mix and CPV in B: hep-ph/0205111v2 Bs-Bs mixing in SO(10) SUSY GUT linked to    mix. hep-ph/0312145 A. Buras, J. Ellis, M.K. Gaillard and D.V. Nanopoulos, Nucl. Phys. B135 (1978) 66 Lepton-quark mass relations first (?) discussed by V H ( CKM ) ( NMS ) ?

54. A. Bay Beijing October 200554 Models beyond the SM SM is believed to be a low-energy effective theory of a more fundamental theory at a higher energy scale (compare situation of classical mechanics and relativistic). Grand Unified Theory (GUT) theories have been suggested to cope with (some of) the SM problems. They predicts that the coupling constants meet at EGUT~10 15-16 GeV EW SSB: SU(2) L U(1) Y  U(1) em g GUT you are here

55. A. Bay Beijing October 200555 SUSY particle superparticle The Minimal Supersymmetric extension of the SM (MSSM) with gauge coupling unification at E GUT = 10 16 GeV predicts the EW mixing parameter: sin 2  W = 0.2336 ± 0.0017 to be compared with the experiemental value sin 2  W = 0.23120±0.00015. The model predicts the existence of new particles.

56. A. Bay Beijing October 200556 How to detect New Physics ? Direct searches: search for new particles, for instance the supersymmetric partners of particles. New phenomenologies, indirect effects: ex.1: proton decay ex.2: EDM measurement ex.3: Hadronic flavour physics very powerful (think to KM prediction of 3 quark families). It can in principle probe very high energies (think to the Z was "seen" in low energy experiments, as an interference effect). Problem: very often complex underlying theory, with large errors.

57. A. Bay Beijing October 200557 Introducing the B mesons family & processes + antiparticles M (B  ) ≈ M (B 0 ) ≈ ≈ 5279 MeV/c 2 lifetime ≈ 1.5 10  12 s mixing/oscillation bs,dq u,c,t W q B0B0 B0B0 d b W W b d W b u,c direct decay loop decay B factories u,c,t

58. A. Bay Beijing October 200558 Where New Physics can show up ?...may modify rates and inject new phases in the processes. For instance: d b W W b d d b b d New FCNC V ts V tb * B0B0 b d s s d K0K0  s W t ??? b d s s d K0K0  s  squark + ? + ? ( The MSSM has 43 additional CP violating phases ! )