Status and Physics of Belle II Sören Lange (University Gießen) 53 rd International Winter Meeting on Nuclear Physics Bormio, Italy,

Transcription

1 Status and Physics of Belle II Sören Lange (University Gießen) 53 rd International Winter Meeting on Nuclear Physics Bormio, Italy, Photo

2 OUTLINE Introduction: SuperKEKB and Belle II Physics (achieved and extrapolated) CP violation Test of CPT invariance Test of T invariance B K* (flavor changing neutral current) search for right-handed couplings exotic, hadronic states: Z+ Status of detectors 2

3 Mt. Tsukuba SuperKEKB asymmetric B meson factory, e+ e BB adjusted to Y(4S) resonance, s=10.6 GeV (7 GeV + 4 GeV) Upgrade: luminosity peak x40, integrated x50 Belle II Detector Linac 3

4 View from KEK, by Klemens Lautenbach ( ) ~200 km Mt. Fuji

5 Belle Belle II Luminosity x 40 L 0.8 x cm 2 s 1 KEKB SuperKEKB originally proposed for SuperB by P. Raimondi (INFN) graphics E. Paoloni (Pisa) 5

6 Background increase x factor

7 (Upgrade of the Belle Detector) 7

8 Belle II Collaboration 650 Members, 99 Institutes, 23 Countries 8

9 Achievement by Belle and BaBar: Observation of CP violation in the B meson system C = charge conjugation symmetry P = parity symmetry 9

10 10

11 Measurement of CP violation at an asymmetric e + e collider ( s=10.6 GeV) Flavor tagging l B 0 l + B 0 Y(4S) e e+ t = z/ c 200 m CP eigenstate reconstruction B J/ K s B + J/ K l Silicon Vertex Detector 11

12 Red: B Mesons, Blue: Anti-B Mesons (B 0 tag), e.g. l + (B 0 tag), e.g. l CP violation is already visible in this plot! 12

13 Precision Measurement of sin(2 at Belle & BaBar Belle, Phys. Rev. Lett. 108(2012) B K S J/ B K L J/ Makoto Kobayashi Toshihide Maskawa V ij are CKM matrix elements (Cabibbo-Kobayashi-Maskawa) A( t) ~ S CP sin( m t) in the SM S CP = sin(2 ) UNITARITY TRIANGLE 13

14 Precision Measurement of sin(2 at Belle & BaBar Belle, Phys. Rev. Lett. 108(2012) BaBar Phys. Rev. D79(2009) B K S J/ B K S J/ B K L J/ B K L J/ Belle and BaBar combined S CP = sin(2 = error dominated by statistics stat. error 0.023! can be largely improved by Belle II and LHCb 14

15 Test of CPT invariance C = charge conjugation symmetry P = parity symmetry T = time reversal symmetry Theorem: CPT is conserved* (Lüders, Pauli, 1954) Violation is possible: - quantum gravity (suppressed by m ² /MPLANCK, M PLANCK =1.2 x 1019 GeV) - string theory (interactions of non-pointlike objects) Colladay, Kostecky, Phys. Rev. D55(1997)6760 *Any Lorentz invariant local quantum field theory with a Hermitian Hamiltonian must have CPT symmetry. 15

16 Assuming CPT invariance Test of CPT Invariance Not assuming CPT invariance with a new, complex CPT violation parameter z 16

17 Test of CPT Invariance t / ps t / ps t / ps Belle, arxiv: [hep-ex] Phys. Rev. D 85(2012)071105(R) 535 x 10 6 BB pairs 17

18 Belle, arxiv: [hep-ex] Phys. Rev. D 85(2012)071105(R) 535 x 10 6 BB pairs Test of CPT Invariance translates to m B /m B = ( ) x K. R. Schubert, arxiv: [hep-ex] can be improved by Belle II by factor 10 compare to (anti)proton m p /m p =7 x PDG 2014 sensitiv to (1/m b 2 ) m B /m B = ( ) x GeV 1 syst. error for Im(z), can be improved by factor 2 (new Belle II vertex detector) 18

19 Test of T invariance 19

20 T Violation l B 0 l + B 0 Y(4S) Y(4S) t B + J/ K l t B J/ K s 20

21 T Violation (K l, l ) only this side! vs. (K s, l + ) only this side! 21

22 T Violation Fit result T-conserving case 2 final states, but 4 asymmetries: time-ordered only positive t left/right, right/left blue line: no T violation BaBar, arxiv: [hep-ex], Phys. Rev. Lett. 109(2012)

23 T BaBar, arxiv: [hep-ex], Phys. Rev. Lett. 109(2012) CP another way to check for CPT invariance (CP violation implies T violation, if CPT is conserved) statistical error dominates improve by factor 10 at Belle II T violation can be investigated in every decay with CP violation 23

24 Search for Right-Handed Couplings 24

25 The Standard Model (SM) [hep-ex] in the SM: neutrinos are left-handed, W bosons are left-handed 25

26 Beyond the Standard Model (BSM) [hep-ex] Are there maybe right-handed neutral leptons, not observed yet? right-handed currents 26

27 How do we know there is physics beyond SM? neutrinos oscillate neutrinos have mass if m 0, then v<c if v<c, then we can find a (faster) reference system, in which the helicity flips (left-handed right-handed) conclusion: there should be a right-handed component (even if small) 27

28 Penguin diagrams Flavor Changing Neutral Current (FCNC) John Ellis (CERN) right-handed couplings physicsforme.de quantumdiaries.org Flip Tanedo,

29 The Big Bang Theory 29

30 The Big Bang Theory 30

31 FCNC B K* (K s 0 ) photon from B(B) dominantly right(left)-handed (because of W boson in the loop) neutral B 0 (CP violation requires B 0 B 0 mixing) Advantages of Belle II: - BB pair production (other side required for flavor tagging) - neutrals: radiative photon and 0 resonant: vector meson e.g. K* non-resonant: self-conjugate K s 0 31

32 FCNC B K* (K s 0 ) CP violation in SM is expected small Belle, 486 fb 1 Phys. Rev. D74(2006)111104(R) S(K* )= (2m s /m b ) sin2 ~0.04 S= (3.5±1.7) 10 2 Matsumori, Sanda, Phys. Rev. D73(2006) S= (2.2± ) 10 2 Ball, Zwicky, Phys. Lett. B642(2006)478 LR symmetric model S(K* )=+0.67 sin2 =0.5 Atwood, Gronau, Soni, Phys. Rev. Lett. 79(1997)185 Grinstein, Grossmann, Ligeti, Pirjol, Phys.Rev.D71(2005) Atwood, Gershon, Hazumi, Soni, Phys. Rev. D71(2005)

33 FCNC B K* (K s 0 ) Extrapolation for Belle II S Belle, Phys. Rev. D74(2006)111104(R) improved resolution PXD+new SVD ΔS(K* γ) = 50 ab 1 Integrated Luminosity / fb 1 33

34 Bounds on scale of new physics based upon existing data Isidori, Teubert, arxiv: [hep-ph] NP 10 2 TeV Factor 3 4 higher for b s and right-handed currents 34

35 Z + States Exotic hadronic states 35

36 Z + (4430) Z(4430) 6.4 not confirmed by BaBar Belle, Phys. Rev D80(2009) Steve Olsen Soo-Kyung Choi Photos: rare evidence from Belle barbecue parties ( 36

37 Z(4430) 6.4 not confirmed by BaBar Belle, Phys. Rev D80(2009) Z 1,Z c1 not confirmed by BaBar Belle, Phys. Rev D78(2008) J P =1 + preferred in all cases 37

38 Confirmation of the Z + (4430) in B 0 K + ' LHCb, arxiv: [hep-ex], Phys. Rev. Lett. 112(2014) data set 3 fb 1, s=7 and 8 TeV significance >13.9 JP =1 + established (exclusion of 0, 1, 2+, 2 by 9.7, 15.8, 16.1 and 14.6 ) mass and width consistent with Belle Product branching fraction ~3 x 10 5 requires B factories 38

39 BESIII (IHEP Beijing) Search for Z + states in other processes Direct Production J PC =1 Belle J PC =1 Initial State Radiation 39

40 Z + (3900) BESIII Belle ISR m = ±3.6±4.9 MeV = 46±10±20 MeV 307±48 events, >8 arxiv: , PRL 110(2013) m = ±6.6±4.5 MeV = 63±24±26 MeV 159±49 events, >5.2 arxiv: , PRL 110(2013) Confirmed with CLEO-c data, but different s not Y(4260) S. Dobbs et al., Phys. Lett. B727(2013)366 40

41 Charged states require minimum configuration of 4 quarks TETRAQUARK (COMPACT) Q q q Q Lattice QCD HADRO-QUARKONIUM TETRAQUARK (DIQUARK- DIQUARK) Q q Q q Q q Q q MOLECULE diquarks can be colored Maiani, Riquer, Piccinini, Polosa, Burns; Ebert, Faustov, Galkin; Chiu, Hsieh; Ali, Hambrock, Wang Fischer, Heupel, Eichmann Q Q q q Q q PION Q q Guo, Hanhard, Meißner, Zhao Tornqvist; Swanson; Braaten, Kusonoki, Wong; Voloshin; Close, Page; Oset Threshold CUSP: Bugg 41

42 Z + states at BESIII m = ±3.6±4.9 MeV = 46±10±20 MeV PRL 110(2013) Events m = ±2.6±3.7 MeV = 24.8±5.6±7.7 MeV arxiv: [hep-ex] Z + (4025) Z + (3900) recoil mass / GeV m = ±1.5±4.2 MeV = 24.8±3.3±11.0 MeV PRL 112(2014) Z + (3885) Events m = ±0.8±2.7 MeV = 7.9±2.7±2.6 MeV arxiv: [hep-ex] Z + (4020) mass(h c )/GeV 42

43 New 2014: Z + (4200) in B meson decays Belle, arxiv: [hep-ex], Phys. Rev. D90, (2014) with Z c (4200)+ without Z c (4200)+? significance 6.2σ also J P = 1 + preferred exclusion level (J P =0, 1, 2, 2 + ): 6.1 σ, 7.4 σ, 4.4 σ, 7.0σ Important negative search result: no evidence for Z + (3900) in B decays <0.1 (if J P =1 + ) 43

44 Spectrum of Z+ States Topic for Belle II 2 different types? from B meson decays 1 + large widths not connected to thresholds? from e+e (direct) or ISR 1 + J P narrow widths near thresholds Only Belle II can investigate both types in same experiment (high statistics ~ Z + (4430) in 50 ab 1 ) 44

45 Status of Belle II 45

46 Installation of 100 new LER Dipole Magnets Install over HER magnets ~3 magnets per day 46

47

48 CDC (Charged Drift Chamber) wire stringing finished (01/2014), wires Belle Belle II Improved resolution: (p T )/p T = 0.19 p T 0.30/ (Belle) 0.11 p T 0.30/ (Belle II) de/dx 6.8% 4.8% 48

49 TOP (Time-of-Propagation Counter) Radiator: Quartz reconstruct Cherenkov angle from (X,Y) time of propagation t Photon detector: Hamamatsu SL10 MCP-PMT t 50 ps single photon sensitivity operated in B=1.5 T field Estimated kaon fake rate factor 2-5 smaller than Belle (@ 95% kaon efficiency) x 49

50 Mirror TOP Assembly of 1 st Module Lifting jig with vacuum chucks Glue joint between two bars Clean KEK, Fuji Hall Prism 50

51 New Belle II Vertex Detector 4-layer SVD R = 3.8, 8.0, 11.5, 14 cm 2-layer PXD R = 1.4, 2.2 cm Beampipe R = 1.0 cm Vertex resolution in beam direction: improvement factor ~2 50 m 25 m 51

52 Belle II DEPFET Pixel Detector 52

53 SuperKEKB Luminosity Extrapolation (2020)

54 SUMMARY - Belle II envisaged start of physics data taking: 10/ Test of symmetries: from CP to CPT and T - CP asymmetries enable new physics search up to scales of 10 2 TeV (in particular: right-handed currents) - Investigation of - Z + in B meson decays - Z + in initial state radiation in same experiment with high statistics 54

55 BACKUP 55

56 Unitarity Triangle Present and Future Belle and BaBar (2012, ~1 ab 1 ) Super KEKB Letter of Intent, 2004 Belle II Expected constraint at 50 ab 1 phi1 old guess 0.014, recent estimate phi2 old 0.9 deg (with rho phi), recent estimate also about 1 deg (rhorho dominated) phi3 old 1.2 deg, recent estimate deg Vub old 4.4% (inclusive), recent estimate 3% inclusive and 2.5% exclusive 56

57 Precision Measurement of sin(2 at LHCb LHCb, Phys. Lett. B 721 (2013) 24 s=7 TeV, 1.0 fb 1 S=0.73 ± 0.07 (stat) ± 0.04 (syst) stat. error factor ~3 larger than Belle and BaBar (combined) syst. error factor ~40 larger than Belle and BaBar (combined) 57

58 New 2014: Z c (4200) + in [J/ ] Belle, arxiv: [hep-ex], Phys. Rev. D90, (2014) with Z c (4200)+ without Z c (4200)+ 58

59 New 2014: Z c (4200) + in [J/ ] Belle, arxiv: [hep-ex], Phys. Rev. D90, (2014) with Z c (4200)+ without Z c (4200)+ 59

60 NEW 2014 Neutral Z states 60

61 121.4 fb 1 Y(5S) decays Z b (10610) 0 decaying to Y(2S) 0, Y(3S) 0 significance 6.5 Neutral Z b Belle, [hep-ex] Phys. Rev. D88(2013) BELLE BELLE cross sections are about factor ½ of p+p consistent with isospin scaling 61

62 Neutral Z b first evidence in CLE0c data at s=4.17 GeV (Phys. Lett. B727(2013)366) BESIII preliminary, QWG2014 e+e J/ 0 0 m=3894.8±2.3±2.7 MeV =29.6±8.2±8.2 MeV significance 10.4 Reminder: charged Zc(3900)+ m = ±3.6±4.9 MeV = 46±10±20 MeV arxiv: , PRL 110(2013)

63 Notes: Isospin Triplet these Z States are I=1 Remember the connection decay Y X, decay Y Z but there is a neutral Z(3900) and a neutral X(3872), and they are different (width >20 MeV vs. width <1 MeV) 63

64 2nd neutral Z c, near D*D* threshold BESIII [hep-ex], Phys. Rev. Lett. 113, (2014) e+e h c 0 0 hc c with 16 reconstructed c decay channels Z c (4020) 0 >5 m=4023.9±2.2±3.8 MeV no width measurement width is fixed to charged Z 64

65 Isospin in Z c (4020) 0 production BESIII, [hep-ex], Phys. Rev. Lett. 113(2014) ratio ½, as expected from isospin scaling (similar to Y(nS) transitions) ratio closer to ~1 (?) (but ½ not excluded) 65

66 Z b + in Y(5S) decays Y(5S) adjust accelerator to s=10.86 GeV Y(5S) maybe exotic itself Y(5S) Y(1S) + factor 10 3 higher than expected Missing mass technique unique for e+e (initial state precisely known) Y(5S) detected + BaBar, [hep-ex], Phys. Rev. Lett. 102(2009) Belle, arxiv: [hep-ex] reconstructed 66

67 Upsilon(5S) R b event selection Belle - N track 3 - one ECL cluster >100 MeV, - total energy in the ECL between 0.1 and 0.8 x s - Evis > 0.5 s - event vertex be within 1.5 (x) and 3.5 (y) cm of the IP - R 2 < 0.2 BaBar - N track 3 - Evis>4.5 GeV - R 2 <0.2 67

68 Z b states Events / 10 MeV h b (1P) Decays 18 Events / 10 MeV h b (2P) Decays M miss ( ) / GeV M miss ( ) / GeV Z b (10610) ± m= ±2.0 MeV, Γ=18.4±2.4 MeV close to BB* threshold Z b '(10650) ± m= ±1.5 MeV, Γ=11.5±2.2 MeV close to B*B* threshold 68

69 Spectrum of Z b + states measured masses are (slightly) above thresholds no [BB] ± state observed (yet), as for Z c J P =1 + strongly favored (Belle, arxiv: [hep-ex]) J P 69

70 Belle II Search for New Physics n=2 for box diagram (e.g. B 0 B 0 mixing) LHC direct search E. Kou, Belle II Open Meeting 11/

71 find decays with smaller n improve stat. and syst. errors new detectors (PXD, TOP), reduce hadronic uncertainties (lattice QCD),... e.g. penguin decays n=1 for b s m>~10 6 TeV in reach E. Kou, Belle II Open Meeting 11/

72 Bounds on M NP (or scale ) based upon existing data Open Symposium on the European Strategy for Particle Physics Isidori, Teubert, arxiv: [hep-ph] M NP 140 TeV (standard left-handed CKM couplings) 72

73 Isidori, Teubert, arxiv: [hep-ph] NP scales with at most N 1/4, where N is relative increase of number of events 1 ab 1 50 ab 1 ( = 2.65) e.g. NP =100 TeV (Belle) 265 TeV (Belle II) 73

74 Direct searches for W' at LHC (lljj) ATLAS, arxiv: [hep-ex], 2.1 fb 1, s=7 TeV mass WR < 2.3 TeV (under some conditions) CMS, arxiv: [hep-ex], 19.7 fb 1, s=8 TeV 2.87 TeV (3.00 TeV) for electron (muon) Yu, Kou, Lü, arxiv: [hep-ph], JHEP12(2013)102 =0.5 for right-handed M w =2.0 TeV =0.3 for right-handed M w =2.5 TeV 74

75 Lepton Flavor Violation flavor changing neutral currents in the lepton sector 75

76 Lepton flavour violation in decays SM predictions are small Br(τ lepton γ) Br(τ 3 leptons)

77 SM predictions are small Br(τ lepton γ) Br(τ 3 leptons) photon only here (requires electrical charge of W bosons) 77

78 CKM Matrix and PMNS Matrix CKM: (quarks) = PMNS: (neutrinos) F. Potter, Prog. Phys. 10(2014)146 78

79 79

80 T. IIjima, TAU2014 Lepton Flavour Violating Tau Decays 80

81 Future prospects for LFV in t decays T. IIjima, TAU2014 Sensitivity extrapolation BG non-free ~ 1/ N expected limit B( ) ~ O(10 9 ) BG free 1 N expected limit B( ) ~ O(10 9 ) O(10 10 ) LHCb may also be able to reach O(10 9 ) with 10 fb 1 81

82 5.7 x 10^ 13 MEG, Phys.Rev.Lett. 110 (2013) but scales with squared mass difference MEG Upgrade Proposal, arxiv: [hep-ex] 82

83 A FB (weak mixing angle) 83

84 Electroweak Unification 84

85 Possible new physics (NP) contributions 85

86 J. Erler, arxiv: [hep-ph] 86

87 Forward-Backward Asymmetry in e+e + at Belle II energies, is small (<<1) little dependence on Weinberg angle! Akeroyd et al., arxiv: [hep-ex[ 87

88 88

89 Measurement of A FB stat. errors are x1000 (otherwise not visible) Limit on new physics contact interaction ansatz Belle II will reach <33 TeV 89

90 R. Waldi, Maria Laach

91 Oscillation Phenomenology = 1/T 91

92 CPT Parameter z 92

93 Eigenstates Mass Eigenstates Flavour Eigenstates CP Eigenstates 93

94 T Violation Assuming ΔΓ=0 (good for B d decays) Adrian Bevan, Queen Mary University of London March

95 G. Isidori et al., Ann.Rev.Nucl.Part.Sci. 60, 355 (2010) B. Golob, KEK FF Workshop, Feb

96 [ Y(5S) Y(nS) ] is huge Y(4S) Y(1S) 477 fb 1 8 times as many events integrated for Y(nS) (4S) (1S) + 1/20 times the data & ~1/10 th the crosssection 2S 3S 44±8 events 4S Phys. Rev. D75(2007)

97 Not only Y(5S) Y(1S) is large, but also Y(5S) Y(2S) 97

98 with crab cavity 98

99 99

100 CDC transport from Fuji Hall to Tsukuba Hall,