50 anni di sensazionali violazioni di CP. Marcello A. Giorgi INFN & Universita di Pisa

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1 50 anni di sensazionali violazioni di CP Marcello A. Giorgi INFN & Universita di Pisa

2 50 YEARS ago was the true astonishing discovery!

3 OUTLINE Pre-History Discovery of CPV in neutral K decay. Explanation inside the Quark model with 3 generations. Validation of the CKM paradigm in K and B decay. Still insufficient to explain the matter-antimatter unbalance in the universe. CP Violation adventure continues in K, B, Charm and Neutrino sector.

4 _ K 0 K 0 and The Pre-History _ K S K L at very beginning From the recollection of Jim Workshop 50 years of CP violation - Queen Mary.University of London July 10-11, 2014.

5 The Pre-History

6 The Pre-History

7 The Mixing The simplest example of mixing in classic mechanichs is given by the two spring coupled penduli constrained to the plane. The time evolution of Kaon system (θ), limiied to two states K 0 and K 0, is governed by an effective non Hermitian Hamiltonian H eff represented by a 2x2 complex matrix with two mixed states K 1 e K 2 as eigenstates. H eff can be decomposed in two hermitian matrices, H eff =M-iΓ/2, with the easy identification of M and Γ as mass and decay matrix.

8 The Mixing K 1 and K 2 have different lifetimes and decay into different non leptonic channels, in a maximal mixing K 1 e K 2 are CP eigenstate K 1,2 = K 0 ± 2 K 0 The decay of K 1 in two pions was already observed (q 0 ), the long lifetime K 2 was seen soon after the Gell-Mann & Pais proposal. Observation of Long-Lived Neutral V Particles. Phys. Rev. 103, 1901 Published 15 September K. Lande, E. T. Booth, J. Impeduglia, L. M. Lederman, andw.chinowsky].

9 The validation of Mixing REGENERATION! IDEA OF PAIS AND PICCIONI K 0 is produced in strong interaction. K 0 and anti K 0 have different interaction cross section with nuclei.

10 The validation of Mixing REGENERATION! The famous experiment of O.Piccioni [Regeneration of neutral K mesons and their masse difference Phys. Rev. 124, 1223 Published 15 November R. H. Good, R. P. Matsen, F. Muller, O. Piccioni, W. M. Powell, H. S. White, W. B. Fowler, and R. W. Birge.]

11 LOOKING for K 2 decaying into 2 pions K 2 is eigenstate of CP with the eigenvalue =-1, it cannot decay in 2 p s.

12 The Missed Discovery (1961) N.B. K L π π is in fact T violation

13 The Misinterpretation(1961) At Brookhaven Adair, Chinowsky and collaborators note an excess of 2 p decays from the decadimenti in 2 p coming from the K 2 line. Their interpretaation is an anomalous regeneration of K 1. (8) [Anomalous Regeneration of Mesons from Mesons.Phys. Rev. 132, 1867 (1963) Published 1 December L. B. Leipuner, W. Chinowsky, R. Crittenden, R. Adair, B. Musgrave, and F. T. Shively.]

14 The Glorious 1964 DISCOVERY! FROM PROPOSAL

15 The Glorious 1964 DISCOVERY! The apparatus

16 The Glorious 1964 Results DISCOVERY! The Paper

17 The Glorious th of Galileo

18 The Glorious th of Galileo

19 400th of Galileo The astonishing Discovery

20 Further Proof

21 Superweak interpretation Wolfenstein, L.; Violation of CP Invariance and the Possibility of Very Weak Interactions Phys. Rev. Lett. 13(1964) 562; CP violation in K decay occurs via a Superweak interaction with S=2. Only in mixing! No direct CP violation with S=1. If CPV is only in mixing then : and ε =0 = = ε

22 CPV from flavour mixing with 6 quarks (Kobayashi&Maskawa 1973) From 2 quark families : Unitarity requires 2x2 real mixing matrix (rotation matrix in two dimensions with Cabibbo angle θ C ). To 3 quark families : flavour mixing matrix with 4 parameters 3D rotation angles and one irreducible complex phase. M. Kobayashi, T. Maskawa(1973). " It explains indirect CPViolation in mixing for K->2 pions and allows prediction for direct CPV ( ε '/ ε 0 ) and for many oservables related to CPV asymmetries in B decays.. M. Kobayashi and T. Maskawa, CP Violation In The Renormalizable Theory Of Weak Interaction, Prog. Theor. Phys. 49(1973) 652

23 Chase for ε! No evidence of Direct CPV for long time

24 Chase for ε! No evidence of Direct CPV before Leipzig (1984)

25 Experimental issues The presence of 4 gammas in the final state requires a very good photon detection, good control of decay position of K S and K L (dimensional scale) and of the acceptance for the two decays. Good control of all systematics. Very intense and clean: neutral beams were also needed New experiments CERN Na31and at FNAL E731

26 The first results of these experiments and Then upgrade in E731 and the evolution to KTEV at FNAL and and Na48 at CERN based on new concept beam, tagging and detector.

27 Talks of M.Sozzi& T. Yamanaka-Queen Mary Workshop,July 2014

28 Towards validation of CKM CP violation in B sector and the measurement of the Unitarity Triangle sides and angles has given a strong support to CKM. This exploration inside the B sector required a strong effort to extract asymmetries in experiments at hadron machines where in the presence of large production cross section and huge background. A new kind of machines : the high luminosity e+ e- asymmetric colliders allowed a clean environment to study with high performance detectors (namely with high precision silicon vertex trackers) the CP violation asymmetries in the interference between flavour mixing and decay amplitude.

29 Time dependent CP violation in BB system Carter, Sanda Phys.Rev.Lett. 45, 952 (1980); Phys.Rev. D23, 1567(1981) Motivation for Asymmetric B Factories =A f cos( mt)+s f sin( mt) Interference Mixing amplitude-decay amplitude λ f 2 1 A f = λ f ϒ S f = 2Im( λ f ) λ f A( Bf ) λ f e 2iφM A( Bf )

30 Time dependent CP violation in BB system

31 PEPII and KEKB KEKB L peak = /cm 2 /s Daily integ. lum. 1 fb -1 /day 1000 fb -1 = 1 ab -1

32 CP Violation Asymmetry

33 2001:CKM validation from Babar (PRL 89(2002)201802) and Belle (PR D 66 (2002)071102) Results are all compatible with a single phase inside the flavour mixing matrix

34 10 th anniversary of Direct CPV in B decay 2004 A CP = Γ( B Γ( B 0 0 f ) Γ( B f ) + Γ( B 0 0 f ) f ) Signal (227 M BB pairs): 1606 ± 51 B A CP 0 K π BABAR + PRL 93 (2004) = ± ± σ Belle Confirmation at ICHEP04 PRL 93 (2004) Signal (274 M BB pairs): 2140 ± 53 = ± ± A CP 3.9σ A Average A CP = ± 0.020

35 From Tevatron new constraints with Bs Confirmation came also from Tevatronexperiments CDF and D0, as in the In addition: First double-sided 90% CL interval for Δm s value was obtained by D0 collaboration m < 21ps < s Measurement of Δm s at 5σlevel was performed by the CDF collaboration m s = ± 0.10 (stat) ± 0.07 (syst) ps Then potting new constraints on CKM parameters: 1 talk of G. Queen Mary Workshop, July 2014

36 Oservation of direct T violation Babar 2012 Everything compatible with what expected from CPT conservation

37 Oservation of direct T violation Babar 2012a lot of rumors on media

38 50 years of (astonishing?) results After the really astonishing discovery of 1964 the Super Weak interaction was ruled out and CP found a motivation within CKM paradigm. It took long time and it was just possible for the development of new and powerful experimental tools: New precise and intense Kaon Beams Highly performing electromagnetic calorimeters for 4 gamma reconstruction New asymmetric e+ e- colliders Precise decay vertices measurements with new silicon vertex detectors. And a strong determination of the experimental physicists.

39 Data are so far in full agreement with CKM

40 Data are so far in full agreement with CKM

41 The matter-antimatter puzzle The A. Sakharov conditions for the Matter-antimatter unbalance in the universe : Baryon instability C violation and CP violation Thermo dynamical non-equilibrium In Standard Model with CKM the Sakharov condition is met as C and CP,but calculations show that it is STILL NOT sufficient to explain the matter-antimatter unbalance. NEW CPV sources and new particles? THE INVESTIGATION MUST CONTINUE!!

42 Towards future in CPV, Test the limits New experiments in the future.:kaons First run October 2014

43 Towards future in CPV LBL experiments or Neutrino factory? From F. Di Lodovico

44 Towards future in CPV LHCb and Belle SuperKEKB (50 ab -1 ) LHCb and BelleII are complementary, they can improve precision on measured channels by almost one order of magnitude. They can access rare decays as well as Kintense kaon beam experiments

45 Towards future