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Matter, Antimatter and CP violation

Matter, Antimatter and CP violation. Aurelio Bay Institut de Physique des Hautes Energies. Séminaire Uni Neuchâtel 27-I-2003. ELECTRON. m. 1. m. 10. -5. QUARKS. The Cosmic Onion. PROTON. NEUTRON. m. -15. 10. }. NOYAU. ATOM. m. 10. -10. m. 10. 7. m. 1. m. 10. 11.

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Matter, Antimatter and CP violation

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  1. Matter, Antimatter and CP violation Aurelio Bay Institut de Physique des Hautes Energies Séminaire Uni Neuchâtel 27-I-2003

  2. ELECTRON m 1 m 10 -5 QUARKS The Cosmic Onion PROTON NEUTRON m -15 10 } NOYAU ATOM m 10 -10

  3. m 10 7 m 1 m 10 11 m 10 20 m 10 22-24 The cosmic onion 2 . Universe

  4. Matter Antimatter and CP violation The Standard Model of particles (and antiparticles) Symmetries Parity (P), Charge Conjugation (C) and Time reversal (T) P and C violation Baryogenesis CP & T violation Experiments Conclusion

  5. MATTER INTERACTIONS Charge [e] n n n The Standard Model Weak : W+ W- Z e m t 0 - - - e 1 m t - E.M. : photon u c t 2/3 Quarks 1/3 d s b - Strong : gluons Spin 1/2 Spin 1 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... !

  6. Oppenheimer, Stückelberg, Feynman suggest to replace E<0 particles with other (anti)particles of opposite charge and E>0 Y describes spin 1/2 particle & antiparticle Antiparticles Paul A. M. Dirac theory of relativistic quantum mechanics in 1927 correctly describes spin 1/2 particle but with a "double" of negative energy...

  7. - e + e B Positrons were observed at CAL-Tech by C. D. Anderson in 1932. Positrons observation Pair creation

  8. Symmetries

  9. In 1915 she links the invariance properties of a Lagrangian to conservation laws Amalie (Emmy) Noether Invariance under: Momentum conserved Translation Rotation Angular mom. conserved Gauge Charge conserved

  10. Symmetries in particle physics Non-observables symmetry transformations conservation law / selection rules difference between permutation B.E. / F.D. statis. identical particles absolute position rr +dp conserved absolute time t  r + t E conserved absolute spatial direction rotation rr'J conserved absolute velocity Lorentz transf. generators L. group absolute right (or left) r-r Parity sign of electric charge q -q Charge conjugation relative phase between states with different charge q y eiqqy charge conserved different baryon nbr B y eiBqy B conserved different lepton nbr L y eiLqy L conserved difference between coherent mixture of (p,n) isospin

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

  12. Discrete symmetries P, C,... P: (x,y,z) -> (-x,-y,-z). C: charge -> -charge. e.m. interactions are P & C invariant

  13. What about T ? If x(t) is solution of F = m d2x/dt2 then x(-t) is also a solution (ex.: billiard balls) Ok with electrodynamics:

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

  15. snif snif Parity violation in biology Humans are mostly right handed: Asymmetry  A = (NR-NL)/(NR+NL) ≈ 0.9  “90%Parity violation" Lemmon and orange flavours are produced by the two "enantiomers" of the same molecule.

  16. 100% P violation in DNA

  17. Too much symmetry... LR LL RR

  18. ? Bacchus, Arianna ? MUSEE ROMAIN DE NYON

  19. P conserved in e.m. and strong 1924 O. Laporte classified the wavefunctions of an atom as either even or odd, parity +1 or -1. In e.m. atomic transitions a photon of parity -1 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.

  20. Parity in weak interactions 6Fermi, 1949 model of W interactions: P conservation assumed 6 C.F. Powell,... observation of two apparently identical particles "tau" and "theta" weakly decaying tau 3 pions theta 2 pions which indicates P(tau) = -1 and P(theta) = + 1 If Parity holds "tau" and "theta" cannot be the same particle. 6 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.

  21. 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)

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

  23. Counter g n 152 Sm NaI Polarimeter: selects g of defined helicity Measurement of neutrino helicity 152 Sm (Goldhaber et al. 1958) Result: neutrinos are only left-handed

  24. P left n Parity P and neutrino helicity n right P symmetry violated at (NL-NR)/(NL+NR) = 100%

  25. C left n - left n Charge conjugation C C transforms particles  antiparticle C symmetry violated at 100%

  26. Last chance: combine C and P ! left right CP Is our Universe CP symmetric ?

  27. matter Big Bang antimatter Big Bang produced an equal amount of matter andantimatter Today: we live in a matter dominated Universe (A)symmetry in the Universe time

  28. Big Bang models are matter/antimatter symmetric Baryo genesisI 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 planet. 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 e+e- annihilation in the Galaxy in the Univers !

  29. sensitivity (0.5 - 20 GeV): He/He ~10-9 C/C ~10-8 AMS

  30. N protons £ 5 10 -8 2.5 10 -10 £ N photons 3 ( ) kT 2 3 N 412 photons/cm  1.202 = 2.7 2 ch p 9 Today (age of Univers 10-20 10 years), Baryo genesisII no antimatter around: the visible Universe contains essentially protons, electrons and photons. The N of photons is very large compared to p and e : This suggests a Big Bang annihilation phase in which matter + antimatter was transformed into photons... -6 3 -6 3 =0.1 =1 10 GeV/cm 10 p/cm r r  matter C

  31. Baryo genesisIII

  32. Starting from a perfectly symmetric Universe: 3 rules to induce asymmetry during evolution BaryogenesisIV 1) $ processes which violate baryonic number conservation: B(t=0) = 0 B(today)>0 B violation is unavoidable in GUT. Andrej Sakarov 1967 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 OK: Universe expands.

  33. q q ou + q e 27 10 { °K q q X ou - q e - + Prob(X qq) = Prob(X qe ) = (1  a  -a) - - - - Prob(X qq) = Prob(X qe ) = (1  b  -b) - - - X qq  Baryogenesis V X CP mirror Requirement: a > b... ... forbidden by CP symmetry ! CP X  qq  a = b

  34. + - e p n { MIRROR provides an absolute definition of + charge CP - + e p n - + + - e N p n e p n - + + - N e e p n p n July 1964: J. H. Christenson, J. W. Cronin, V. L. Fitch et R. Turlay find asmall CP violation with K0 mesons!!! CP violation S. Bennet, D. Nygren, H. Saal, J. Steinberg, J. Sunderland (1967): K 0 L K 0 L 0 K is its own antiparticle L CP symmetry implies identical rates. Instead... - N % 0.3  + N

  35. CP violation experiment

  36. K0 K0 CPLear Processes should be identical but CPLear finds that neutral kaon decay time distribution  anti-neutral kaon decay time distribution Other experiments: NA48, KTeV, KLOE f factory in Frascati, ...

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

  38. CPT Schwinger-Lüders-Pauli show in the '50 that a theory with locality, Lorentz invariance spins-statistics is also CPT invariant. Consequences: * Consider particle y 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,...

  39. oscillations s t d W W K0 s d t K0 0 T from CPLear (6.61.6)10-3

  40. Electric Dipole Moments Energy shift for a particle with EDM d in a weak electric field E is linear in E: DE = E d . d can be calculated from d =  ri qi which is left unchanged by T: q aq T: rar 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: Ja-J This implies k = 0 if T is a good symmetry: d = 0

  41. E D M 2 expt [e cm] SM prediction proton ( - 4  6 ) 10-23 10-31 neutron < 0.63 10-25 ( 95% CL) 10-31 electron ( 0.07  0.07 ) 10-26 10-38 muon ( 3.7  3.4 ) 10-19 10-35 129-Xe <10-27 199-Hg <10-28 muon measurement in future "neutrino factories"  10-24 No signal of T violation "beyond the Standard Model" so far !

  42. CP & T violation only in K0 system ??? Since 1964, CP and or T violation was searched for in other systems than K0, other particles decays, EDM... No other signal until 2001...

  43. 8 GeV electrons 3.5GeV positron BaBar (SLAC) and Belle (KEK) in 2001: observation of CP violation in the B meson system, using "asymmetric collider" B factories. KEKB machine:  production of (4s) (10.58GeV/c2)  = 0.425 (4s)  B0 B0  B+ B-

  44. BaBar and Belle Study of the time dependent asymmetry in decay rates of B0 and anti-B0 CP violated  S ≠ 0 Dm = mass difference of "mass eigenstates" ~ 0.49 1012h/s

  45. (4s) J/Y Ks Dz z1 z2 z fCP region of B0 & B0 coherent evolution CP measurements at Belle Difficult: B0 mean life 1.54 10-12 s Δz  cβγΔt ~ 200 m at Belle B0 and anti-B0 oscillate coherently (QMuntangled state). When the first decays, the other is known to be of the opposite flavour  use the other side to infer the flavour, B0 or anti-B0, of the fCP parent e n D

  46. ACC Silicon Vertex Detector SVD Impact parameter resolution  55m for p=1GeV/c at normal incidence Central Drift Chamber CDC (Pt/Pt)2 = (0.0019 Pt)2 + (0.0030)2 K/ separation : dE/dx in CDC dE/dx =6.9% TOFTOF = 95ps Aerogel Cerenkov ACC Efficiency = ~90%, Fake rate = ~6% 3.5GeV/c , e : CsI crystals ECL E/E ~ 1.8% @ E=1GeV e : efficiency > 90% ~0.3% fake for p > 1GeV/c KL and  : KLM (RPC)  : efficiency > 90% <2% fake at p > 1GeV/c Belle 103 fb-1 108 B pairs ~ 8 m

  47. Belle micro-vertex detector spatial resolution Blepton + X sz (lepton) ~ 100 mm

  48. Belle event

  49. CP CP is violated in the B0 system

  50. Origin of CP violation Hamiltonian H = H0 + HCP with HCP responsible for CP violation. Let's take HCP = 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 HCP CP† = CP (gH + g*H†) CP† = gH† + g*H CP invariance : HCP = CP HCP 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.

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