A. Bay Beijing October 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 ?

A. Bay Beijing October 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

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

A. Bay Beijing October 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

A. Bay Beijing October 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.

A. Bay Beijing October 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:

A. Bay Beijing October 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 =

A. Bay Beijing October 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.

A. Bay Beijing October % P violation in DNA

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

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

A. Bay Beijing October Some asymmetry introduces more dynamics

A. Bay Beijing October 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.

A. Bay Beijing October 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.

A. Bay Beijing October 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)

A. Bay Beijing October Co 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

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

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

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

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

A. Bay Beijing October (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

A. Bay Beijing October 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

A. Bay Beijing October sensitivity ( GeV): He/He ~10  C/C ~10  AMS

A. Bay Beijing October Baryogenesis.2 Today (age of Univers 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 = GeV/cm 3  p/cm 3 N protons N photons     

A. Bay Beijing October 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

A. Bay Beijing October Baryogenesis.4

A. Bay Beijing October 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

A. Bay Beijing October 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 °K... forbidden by CP symmetry !  { X  qq X  qq CP mirror

A. Bay Beijing October 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

A. Bay Beijing October CP violation experiment

A. Bay Beijing October 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,...

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

A. Bay Beijing October 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,...

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

A. Bay Beijing October 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

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

A. Bay Beijing October 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 In 2001 Babar at SLAC and Belle at KEK observe a large CP vioaltion in the B0-B0bar system

A. Bay Beijing October 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.

A. Bay Beijing October 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...

A. Bay Beijing October 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  cabibbo ~ 12° In the 1970 the "flavour mixing" matrix was

A. Bay Beijing October 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 !

A. Bay Beijing October 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:

A. Bay Beijing October 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

A. Bay Beijing October CKM matrix.3 downstrange beauty up charm top 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)

A. Bay Beijing October 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:

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

A. Bay Beijing October 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

A. Bay Beijing October          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

A. Bay Beijing October 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

A. Bay Beijing October 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

A. Bay Beijing October Cosmics

A. Bay Beijing October 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.

A. Bay Beijing October Any horizontal symmetry ? CPV, mix., baryogenesis: hep-ph/ v2 * Neutrino mix and CPV in B: hep-ph/ v2 Bs-Bs mixing in SO(10) SUSY GUT linked to    mix. hep-ph/ 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 ) ?

A. Bay Beijing October 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~ GeV EW SSB: SU(2) L U(1) Y  U(1) em g GUT you are here

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

A. Bay Beijing October 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.

A. Bay Beijing October Introducing the B mesons family & processes + antiparticles M (B  ) ≈ M (B 0 ) ≈ ≈ 5279 MeV/c 2 lifetime ≈  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

A. Bay Beijing October 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 ! )