CP violation and rare decays

Transcription

1 CP violation and rare decays (of heavy flavour hadrons) Rencontres de Blois 28 th meeting on Particle Physics and Cosmology Blois, France, 30 May-3 June 2016 T. Nakada EPFL-IPHYS-LPHE Lausanne, Switzerland

2 To start My first experience in participating in a conference in this palace was: Workshop on CP Violation and Beauty Factories and Related Issues in Physics, Blois, France, 26 Jun-1 Jul 1989, organised y D. Cline and A.Fridman, talking aout The B-meson factory project at the Paul Scherrer Institute (PSI) Among the speakers, there was S. Stone (Session summary : CP violation and rare decays) That was the time of ARGUS vs CLEO Now almost 30 years later, CESR, DORIS-II, LEP, Tevatron, PEP-II, KEKB, HERA-B completed ATLAS, CMS and LHC are in the middle of physics production. SuperKEKB in construction, LHC upgrade in preparation T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

3 To start My first experience in participating in a conference in this palace was: Workshop on CP Violation and Beauty Factories and Related Issues in Physics, Blois, France, 26 Jun-1 Jul 1989, organised y D. Cline and A.Fridman, talking aout The B-meson factory project at the Paul Scherrer Institute (PSI) Among the speakers, there was S. Stone (Session summary: CP violation and rare decays) That was the time of ARGUS vs CLEO Now almost 30 years later, CESR, DORIS-II, LEP, Tevatron, PEP-II, KEKB, HERA-B completed ATLAS, CMS and LHC are in the middle of physics production. SuperKEKB in construction, LHC upgrade in preparation T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

4 To start My first experience in participating in a conference in this palace was: Workshop on CP Violation and Beauty Factories and Related Issues in Physics, Blois, France, 26 Jun-1 Jul 1989, organised y D. Cline and A.Fridman, talking aout The B-meson factory project at the Paul Scherrer Institute (PSI) Among the speakers, there was S. Stone (Session summary: CP violation and rare decays) That was the time dominated y ARGUS vs CLEO World of heavy flavour: almost 30 years later, CESR, DORIS-II, LEP, Tevatron, PEP-II, KEKB, HERA-B completed LHC, BESS-II, VEPP-4, VEPP-2000 are in the middle of physics production. SuperKEKB in construction, LHC upgrade in preparation T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

5 In the very past Rare processes have een crucial for estalishing the Standard Model in the past: Some examples are T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

6 In the very past Rare processes have een crucial for estalishing the Standard Model in the past: Some examples are From Br(K L µ + µ - ) and K 0 -K 0 oscillations (Δm K ) Glashow-Iliopoulos-Maiani mechanism(1970), Value of m c Lee&Gaillard (1974) Charm discovery Auert et al., Augustin et al., 1974 (Niu et al. 1971?) CP violation: J.H. Christenson et al. (1964), Br(K 0 L π+ π - ) 0 Third family introduced y Koayashi & Maskawa (1973) Beauty discovery S. Her et al. (1977) B 0 -B 0 oscillations (Δm B ): ARGUS (1987) m t > 50 GeV/c 2 (NB: UA < m t < 50 GeV/c 2 ) top discovery y CDF and D0 in 1995 (m t = ± 2.1 GeV/c 2 ) T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

7 In the very past Rare processes have een crucial for estalishing the Standard Model in the past: Some examples are From Br(K L µ + µ - ) and K 0 -K 0 oscillations (Δm K ) Glashow-Iliopoulos-Maiani mechanism(1970), Value of m c Lee&Gaillard (1974) Charm discovery Auert et al., Augustin et al., 1974 (Niu et al. 1971?) CP violation: J.H. Christenson et al. (1964), Br(K 0 L π+ π - ) 0 Third family introduced y Koayashi & Maskawa (1973) Beauty discovery S. Her et al. (1977) B 0 -B 0 oscillations (Δm B ): ARGUS (1987) m t > 50 GeV/c 2 (NB: UA < m t < 50 GeV/c 2 ) top discovery y CDF and D0 in 1995 (m t = ± 2.1 GeV/c 2 ) Indirect evidences efore the direct discovery! T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

8 By the early 90 s The Standard Model model description of flavour through the Caio-Koayashi-Maskawa mass mixing matrix estalished well enough (nuclear β decays, kaon decays, charm decays and decays, in particular with ε K and Δm d with little uncertainty from the still unmeasured m t ), to make a firm statement such as If CPV is generated y the CKM phase, CPV in the B J/ψK S decays must e oserved with >5σ within a few years of running with an asymmetric B factory with a luminosity of ~10 33 cm -2 s -1 T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

9 By the early 90 s The Standard Model model description of flavour through the Caio-Koayashi-Maskawa mass mixing matrix estalished well enough (nuclear β decays, kaon decays, charm decays and decays, in particular with ε K and Δm d Unitarity with little triangle uncertainty in early from 90 s the still unmeasured m t ), to make a firm statement such as Note that the apex is in the second quadrant. If CPV is generated y the CKM phase, CPV in the B J/ψK S decays must e oserved with >5σ within a few years of running with an asymmetric B factory with a luminosity of ~10 33 cm -2 s -1 This was the main motivation for asymmetric B factories T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

10 By the early 90 s The Standard Model model description of flavour through the Caio-Koayashi-Maskawa mass mixing matrix estalished well enough (nuclear β decays, kaon decays, charm decays and decays, in particular with ε K and Δm d with little uncertainty from the still unmeasured m t ), to make a firm statement such as If CPV is generated y the CKM phase, CPV in the B J/ψK S decays must e oserved with >5σ within a few years of running with an asymmetric B factory with a luminosity of ~10 33 cm -2 s -1 This was the main motivation for asymmetric B factories T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

11 Two major events on CPV in Discovery of CP violation in the decay amplitudes, i.e. Re(ε /ε) A(K 0 ππ) - A(K 0 ππ) 0: fixed target Superweak model (Wolfenstein 1964) was finally excluded as a (major) source of CP violation CPV only in ΔS = 2 transitions s d u c W + W - u c d s s d d s T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

12 Two major events on CPV in Discovery of CP violation in the decay amplitudes, i.e. Re(ε /ε) A(K 0 ππ) - A(K 0 ππ) 0: fixed target = 3Re(ε /ε) Effort over 30 years! T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

13 Two major events on CPV in Discovery of CP violation in B d J/ψK S decays, i.e. sin 2β N(B 0 t=0 J/ψK S at t) - N(B0 t=0 J/ψK S at t) 0 two e + e - B factories sin 2β T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

14 Two major events on CPV in Discovery of CP violation in B d J/ψK S decays, i.e. sin 2β N(B 0 t=0 J/ψK S at t) - N(B0 t=0 J/ψK S at t) 0 two e + e - B factories First concrete indication that the Standard Model appears to e the (major) source of CP violation T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

15 Since then till the LHC start up BABAR and Belle, with high statistics B u and B d sample, successfully demonstrated that the quark flavour can e quantitatively well descried y the CKM mechanism of the Standard Model, including CP violation. Their analysis went well eyond the original expectations, e.g. angle γ (φ 3 ) measurement. CDF and D0 have started to explore the B s meson system: e.g. discovery of B s -B s oscillations: However, CP violation in the B s system remained as a largely unexplored territory, as well as very rare decays, e.g. B s,d µ + µ -, and high statistic decay topology studies of rare decays, e.g. B d K *0 µ + µ -. Several evidences were seen for D-D oscillations, ut statistics were not enough to explore CP violation. T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

16 Triumph of the CKM description All the flavour changing processes are descried y the four parameters of the CKM mass mixing matrix (λ, A, ρ, η) From this plot, we know already either new physics energy scale is >> TeV (far eyond LHC) or the flavour structure of new physics is very special. T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

17 NB: Parallel session talks relevant to this suject See for more detailed information and references Rare decays at LHC Eluned Smith (ICL, GB) Recent results on B-meson decays at BaBar and Belle Guy Wormser (LAL, FR) Rare Decays of B 0 (s) Mesons to Muon Pairs with the ATLAS Detector (Run 1) Wolfgang Walkowiak (Siegen, DE) CP violation in B and charm decays at LHC Simon Akar (CPPM, FR) Charm Physics at BESIII Peilian Liu (IHEP, CN) Recent heavy flav. Tevatron Rick Van Kooten (Indiana, US) Proing new physics with rare kaon decays at CERN SPS Venelin Kozhuharov (LNF, IT and Sofia, BG) T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

18 And now: test of the CKM picture Confirming the CKM picture search for new physics Γ( ulν), γ trees: not (much) affected y BSM Δm, CPV(B J/ψ+K S or φ), CPV(K-K), B µµ oxes and penguins: can e affected y BSM T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

19 Some of the relevant diagrams Box generated rare decays: B s, B d µ + µ - d s W + W - ν µ CPV in B s -B s oscillations: B s B s B s B s s u c t dispersive t W + W t - + new virtual particles? CPV in oscillations decay: B s J/ψφ B s J/ψφ s t W + W t - + new virtual particles? µ + µ - d s + new virtual particles? s s s u c t W + W - Z 0 asorptive c u W + W c u - Tree diagrams c W s µ + µ - s T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

20 And now: test of the CKM picture Confirming the CKM picture search for new physics Γ( ulν), γ trees: not (much) affected y BSM Δm, CPV(B J/ψ+K S or φ), CPV(K-K), oxes and penguins: can e affected y BSM T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

21 And now: test of the CKM picture Confirming the CKM picture search for new physics Γ( ulν), γ trees: not (much) affected y BSM Δm, CPV(B J/ψ+K S or φ), CPV(K-K), oxes and penguins: can e affected y BSM Agreement with the CKM picture is still good! (flavour prolem for new physics) T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

22 No real sign of new particles in loops yet! Box generated rare decays: B s, B d µ + µ - d s u c t W + W - ν µ µ + µ - d s + new virtual particles? u c t W + W - Z 0 µ + µ - CPV in B s -B s oscillations: B s B s B s B s s dispersive t W + W t - + new virtual particles? s CPV in oscillations decay: B s J/ψφ B s J/ψφ s t W + W t - + new virtual particles? s s asorptive c u W + W c u - Tree diagrams c W s s T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

23 The CKM picture still works well, ut Improvements are needed for: inclusive versus exclusive measurements of V u (and V c ) Primarily a theoretical issue, ut experiments can help y providing more data (precision and extending scope): future Belle II for B X u lν decays Exclusive -aryon decays y LHC (eyond meson decays) currently, V u extracted from the Λ plν decays agrees with V u extracted from the exclusive B meson decays. Angle γ measurement need to improve. Need to reduce the error on φ s (CPV in B s J/ψKK and J/ψππ) to ~O(10-2 ) rad, i.e. at a level of the SM expectation Need to reduce experimental errors in B d, B s µ + µ - Beyond -hadron decays: K + π + νν for V ts V td (NA62) K L π 0 νν for η (height of the triangle) measurement (KOTO) Improving lattice calculations for ε /ε. T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

24 V u exclusive vs inclusive B inclusive (4.41± ) 10-3 B exclusive (3.28±0.29) 10-3 Λ exclusive (3.27±0.15±0.16±0.06) 10-3 PDG 2014 Nature Physics 11, (2015) Λ plν + lattice QCD compared to B-ρlν, πlν much less ackground T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

25 The CKM picture still works well, ut Improvements are needed for: inclusive versus exclusive measurements of V u (and V c ) Primarily a theoretical issue, ut experiments can help y providing more data (precision and extending scope): future Belle II for B X u lν decays Exclusive -aryon decays y LHC (eyond meson decays) currently, V u extracted from the Λ plν decays agrees with V u extracted from the exclusive B meson decays. Angle γ measurements need to improve. Need to reduce the error on φ s (CPV in B s J/ψKK and J/ψππ) to ~O(10-2 ) rad, i.e. at a level of the SM expectation Need to reduce experimental errors in B d, B s µ + µ - Beyond -hadron decays: K + π + νν for V ts V td (NA62) K L π 0 νν for η (height of the triangle) measurement (KOTO) Improving lattice calculations for ε /ε. T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

26 Angle γ (Akar) BABAR&BELLE LH and future BELLE II&LHC γ = ( ) PRD2013 γ = ( φ 3 = ( ) LHC-CONF ) CKM2013 c.f. γ from a gloal fit = ( ) CKM2015 T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

27 The CKM picture still works well, ut Improvements are needed for: inclusive versus exclusive measurements of V u (and V c ) Primarily a theoretical issue, ut experiments can help y providing more data (precision and extending scope): future Belle II for B X u lν decays Exclusive -aryon decays y LHC (eyond meson decays) currently, V u extracted from the Λ plν decays agrees with V u extracted from the exclusive B meson decays. Angle γ measurements need to improve. Need to reduce the error on φ s (CPV in B s J/ψKK and J/ψππ) to ~O(10-2 ) rad, i.e. at a level of the SM expectation Need to reduce experimental errors in B d, B s µ + µ - Beyond -hadron decays: K + π + νν for V ts V td (NA62) K L π 0 νν for η (height of the triangle) measurement (KOTO) Improving lattice calculations for ε /ε. T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

28 Current status of φ s measurements SM predictions: φ s : CKM fitter ΔΓ s : M. Artuso, G. Borissov and A. Lenz Quite some way to go to reach a SM level sensitivity: LHC experiments T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

29 The CKM picture still works well, ut Improvements are needed for: inclusive versus exclusive measurements of V u (and V c ) Primarily a theoretical issue, ut experiments can help y providing more data (precision and extending scope): future Belle II for B X u lν decays Exclusive -aryon decays y LHC (eyond meson decays) currently, V u extracted from the Λ plν decays agrees with V u extracted from the exclusive B meson decays. Angle γ measurements need to improve. Need to reduce the error on φ s (CPV in B s J/ψKK and J/ψππ) to ~O(10-2 ) rad, i.e. at a level of the SM expectation Need to reduce experimental errors in B d, B s µ + µ - Beyond -hadron decays: K + π + νν for V ts V td (NA62) K L π 0 νν for η (height of the triangle) measurement (KOTO) Improving lattice calculations for ε /ε. T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

30 B d, B s µµ from CMS+LHC (Smith) Branching fractions ( ) (B d ) 3.2σ ( ) 10-9 (B s ) 6.2σ T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

31 Now joined y ATLAS (Walkowiak) T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

32 Now joined y ATLAS (Walkowiak) Further improvements on Br(B s µµ) Estalish B d µµ decay for the LHC experiments NB: possile ackground: ~O(10 5 ) more B d ππ T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

33 The CKM picture still works well, ut Improvements are needed for: inclusive versus exclusive measurements of V u (and V c ) Primarily a theoretical issue, ut experiments can help y providing more data (precision and extending scope): future Belle II for B X u lν decays Exclusive -aryon decays y LHC (eyond meson decays) currently, V u extracted from the Λ plν decays agrees with V u extracted from the exclusive B meson decays. Angle γ measurements need to improve. Need to reduce the error on φ s (CPV in B s J/ψKK and J/ψππ) to ~O(10-2 ) rad, i.e. at a level of the SM expectation Need to reduce experimental errors in B d, B s µ + µ - Also eyond -hadron decays: K + π + νν for V ts V td (NA62) K L π 0 νν for η (height of the triangle) measurement (KOTO) Improving lattice calculations for ε /ε. T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

34 NA62 (Kozhuharov) and KOTO T. Nomura Talk at J-PARC PAC T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

35 Interesting signals in semileptonic decays? With sll loop decays: Angular distriution of the B K *0 ll decays (Lorentz structure) B(K)= Br(B Kµµ)/Br(B Kee) l + W With clν tree decays: R(D (*) )=Br(B D (*) τν)/br(b D (*) µν) + ν t l - W s l + l - W + t Ζ 0 W l + ν c s T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

36 B 0 K *0 l + l - (l=e&µ) (Smith, Wormser) T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

37 Interesting signals in semileptonic decays? With sll loop decays: Angular distriution of the B K *0 ll decays (Lorentz structure) B(K)= Br(B Kµµ)/Br(B Kee) l + W With clν tree decays: R(D (*) )=Br(B D (*) τν)/br(b D (*) µν) + ν t l - W s l + l - W + t Ζ 0 W l + ν c s T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

38 R(K) Status (Smith) T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

39 Interesting signals in semileptonic decays? With sll loop decays: angular distriution of the B K *0 ll decays B(K)= Br(B Kµµ)/Br(B Kee) With clν tree decays: R(D (*) )=Br(B D (*) τν)/br(b D (*) µν) l + ν t l - s W + l + l - t Ζ 0 l + ν c s T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

40 R = Br B D (*) τν / Br B D(*) µν including new Belle result R(D) = , H. Na et al., PRD 2015 R(D*)= , S.Fajfer, J.F.Kamenik, and I.Nisandzic, PRD 2012 T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

41 Interesting signals in semileptonic decays? With sll loop decays: angular distriution of the B K *0 ll decays B(K)= Br(B Kµµ)/Br(B Kee) LHC investigating other decay modes generated y the same diagrams: Will a consistent picture emerge? Big challenge for theory: non-perturative QCD! helicity of multi-ody hadronic system? With clν tree decays: R(D (*) )=Br(B D (*) τν)/br(b D (*) µν) T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

42 Interesting signals in semileptonic decays? With sll loop decays: angular distriution of the B K *0 ll decays B(K)= Br(B Kµµ)/Br(B Kee) LHC investigating other decay modes generated y the same diagrams: Will a consistent picture emerge? Big challenge for theory: non-perturative QCD! helicity of multi-ody hadronic system? With clν tree decays: R(D (*) )=Br(B D (*) τν)/br(b D (*) µν) LHC will improve the R(D * ). And clever trick for R(D)? Improvement y BELLE II Also B τν remains to e an interesting channel (B µν, B c τν?) T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

43 A note added Charm sector seems to ehave normally, again, for the moment (Acar, Liu) No CPV oserved indication of large CPV oserved y LHC not confirmed D-D mixing firmly estalished, ut SM prediction difficult due to large hadronic effects CPV in B s -B s oscillation not confirmed (Acar) Much more data expected from LHC in the coming years And apology for neglecting many other interesting results! And apology for neglecting many other interesting results! T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

44 A note added Charm sector seems to ehave normally, again, for the moment (Acar, Liu) No CPV oserved indication of large CPV oserved y LHC not confirmed D-D mixing firmly estalished, ut SM prediction difficult due to large hadronic effects CPV in B s -B s oscillation not confirmed (Acar) Much more data expected from LHC in the coming years And apology for neglecting many other interesting results! And apology for neglecting many other interesting results! T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

45 Also important to rememer Results will come from charge lepton violating µ decays; 3e, eγ, µ-e conversion and, and τ decays, 3µ, µγ, eγ Flavour conserving quantities such as neutron electric dipole moment and (g-2) µ i.e. flavour should e considered more gloally. Accurate Standard Model predictions are essential in the precision measurements. Strong interactions are still the most prolematic issue in many measurements help from our theory friends are always needed! By the way, axions have not een discovered so far, and θ QCD <10-10 appears to me as another fine tuning T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

46 Reflection CP violation & rare decays made essential contriutions to estalish the flavour structure of the SM in the past. With LHC data, possiility of large BSM physics in the B s sector has een eliminated, and overall status with current data involving quark flavour is in good agreement with the CKM picture, including processes with loop diagrams. Despite of cosmological proof for new physics as well as the neutrino mass, and many clever theoretical works, we have little idea for the energy threshold of new physics. We need to oserve a clear sign of BSM, directly or indirectly, in particle physics, to figure out the energy scale. And I am afraid there is no ovious road for a discovery, thus pursuits must e carried away as wide as possile T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

47 More Reflection In quark flavour physics, there are interesting indications involving semileptonic final states: statistical flacuation? Soft-QCD not yet well understood? Or new physics in electroweak penguins, charged Higgs, leptoquark, etc. etc. etc.. We should remain prudent (we saw so many tantalising signal disappeared), ut not e shy. And the exploitation at LHC has just started (Run-2, Run-3, Run-4, )! T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48

48 My standard joke of the past years T. Nakada (EPFL), CP Violation and Rare Decays Rencontres de Blois, Blois, France, August /48