Exploring Matter- Antimatter Asymmetries with B mesons. David B. MacFarlane SLAC National Accelerator Laboratory

Transcription

1 Exploring Matter- Antimatter Asymmetries with mesons Davi. MacFarlane SLAC National Accelerator Laboratory

2 A funamental cosmological question The universe is now matter ominate: how i this matter- antimatter imbalance arise? o Anti-proton/proton ratio ~1-4 in cosmic rays; no evience for annihilation photons from intergalactic clous Cosmological generation of asymmetry: Sakharov conitions (1 967) o o o aryon number violation, e.g., proton ecay Thermal non-equilibrium Violation of charge conjugation C an parity P iscrete symmetries Unbroken Phase: Massless quarks roken Phase: Massive quarks, W, Z bosons Transition to broken electroweak symmetry provies these conitions D.Morrissey 2

3 Matter- Antimatter annihilation EW symmetry breaking woul preict n /n γ ~ 1-2 No longer possible after about.1s GUT Era Electroweak Era Particle Era Temperature too low to prouce nucleon pairs Observe n /n γ ~ 1-1 Implies 1-1 matter-antimatter asymmetry at.1s after big bang 3

4 Matter AAR, summer 22 ( b ) mesons Proper time 7/27/211 D.MacFarlane at Notre Dame 4

5 Matter- Antimatter asymmetry! Matter AAR, summer 22 Antimatter ( b ) mesons ( b ) mesons Proper time 5

6 rief review of Stanar Moel weak interactions for quarks an CP violation 6

7 Quark couplings: CKM matrix Mass Eigenstates Weak Eigenstates Quark Mixing c u Flavor changes through mixe couplings to quarks b W gv cb b W gv ub Cabibbo-Kobayashi-Maskawa (CKM) Matrix V Vus V u ub V = CKM V V c cs Vcb V Vts V t tb Unitary matrix escribe for 3 generations of quarks by 3 rotation angles an 1 non-trivial phase 7

8 CKM matrix: a source of CP violation V Vus V u ub V = CKM V V c cs Vcb V Vts V t tb CKM elements & quark masses are funamental constants emerging from EW symmetry breaking Wolfenstein parameterization: Observe experimental hierarchy λ ~.22 sinθ C Cabibbo angle V CKM ( i ) λ /2 λ Aλ ρ η 2 2 λ 1 λ /2 Aλ 3 2 λ ( ρ η) λ A 1 i A ~λ 3 2 ~λ ~λ 3 Phase: changes sign uner CP 8

9 Important iscrete symmetries Parity, P o o Reflection a system through the origin, thereby converting right-hane into lefthane coorinate systems Vectors (momentum) change sign but axial vectors (spin) remain unchange Charge Conjugation, C o Change all particles into anti-particles an vice versa Time Reversal, T o Reverse the arrow of time, reversing all time-epenent quantities, e.g. momentum Goo symmetries of strong an electromagnetic forces, but C & P are violate in the weak interaction r p L r p L + + e e γ γ t t 9

10 Is CP a goo symmetry of Nature? Not Quite! Dominant ecay moes for neutral kaons: K K S + ππ CP = πππ L CP = 1 In 1964, Christenson et al. observe: K + ( KL ππ ) + ( KS ππ ) K ~ K + ε K L CP = 1 CP =+ 1 Γ ππ with = 2.3x1 Γ + 3 L CP symmetry is violate at a tiny rate in the ecays of neutral kaons! More recently, irect CP violation also observe ε = η + ρ mt CKM Preicts: 3x1 A K 1 A(1 ) 94 Difficult to interpret ue to complications of haronic physics Is this the origin? 1

11 Weak ecays of mesons meson iscovere: e b W ν e u Rare: ecays to non-charm V Vus V u ub V = CKM V V c cs Vcb V Vts V t tb q b q W q e c q - ν e Vub Vcb 3 Aλ Dominant: ecays to charm 2 Aλ 1986: meson long live 11

12 ARGUS at DESY, Prouce matterantimatter pairs + ee ϒ(4 S) 12

13 ARGUS at DESY, Prouce matterantimatter pairs + ee ϒ(4 S) y the time of ecay 1 2 Matter-Antimatter oscillations! 13

14 Weak ecays of mesons Meson = (bu) or (b) state V Vus V u ub V = CKM V V c cs Vcb V Vts V t tb b t b q W W W W W W t b b q b s t t - e ν e u q e c q - ν e s Rare: ecays to non-charm Vub Vcb 3 Aλ Dominant: ecays to charm VV 2 Aλ Matter-Antimatter oscillations Aλ * 3 tb t 14

15 Weak interaction in Stanar Moel Unitarity Triangle as a summary of Stanar Moel b physics * * * Unitarity: VuVub + VcVcb + Vt Vtb = Unitarity = probability preserving η Apex at ( ρ, η) Vu Vus Vub V = V cs cb c V V Vt Vts Vtb + phases Γ( b u ν ) Raiative penguin ecays - mixing (,) ( 1, ) ρ τ an Γ( b c ν) 15

16 Existing constraints Vub ε K m m m / s 16

17 Weak interaction in Stanar Moel Unitarity Triangle as a summary of Stanar Moel b physics * * * Unitarity: VuVub + VcVcb + Vt Vtb = Unitarity = probability preserving η Apex at ( ρ, η) Vu Vus Vub V = V cs cb c V V Vt Vts Vtb + phases Γ( b u ν ) (,) γ α = φ 3 = φ 2 CP violation τ an Γ( b c ν) - mixing ( 1, ) ρ β Raiative penguin ecays = 1 φ 17

18 CP violation in the system Analogous to a two-slit quantum interference experiment! CPV through interference of ecay amplitues A 1 f Ae 2 iϕ wk e i δ st A 2 +ϕ wk ϕ wk wk st ( ) i ϕ i δ Γ f = A + Ae e 1 2 wk st ( ) i ϕ i δ Γ f = A + Ae e A 1 δ st Γ( f) Γ( f ) for ϕ an δ wk st 18

19 CP violation in the system CPV through interference between mixing an ecay amplitues A e CP iϕ f f CP Directly relate to CKM angles for single ecay amplitue Time-epenent asymmetry q = e p 2i β A e CP i ϕ f Γ( phys ( t) fcp ) Γ( phys ( t) fcp ) f ( ) = = sin cos CP f CP f CP Γ( phys ( t) fcp ) +Γ( phys ( t) fcp ) A t S mt C mt S f CP 2 2Imλf 1 λ CP f q A CP fcp = 2 C 1 + f = λ CP 2 f = λ 1 + CP λ p A f CP f CP f CP 19

20 CP violation in the system CPV through interference between mixing an ecay amplitues A e CP iϕ f f CP Directly relate to CKM angles for single ecay amplitue Time-epenent asymmetry q = e p 2i β A e CP i ϕ f S f CP Γ( phys ( t) fcp ) Γ( phys ( t) fcp ) f ( ) = = sin CP f CP Γ( phys ( t) fcp ) +Γ( phys ( t) fcp ) A t S mt 2 2Imλf 1 λ CP f q A CP fcp = = Imλ 2 fcp C = 1 + f = λ CP 2 f = λ 1 + CP λ p A f CP For simple case shown with single ecay mechanism f CP f CP 2

21 ut how big are the CP asymmetries? b W + c c s J /ψ K K S CP Eigenstate: η CP = -1 ( phys ( t) fcp ) ( phys ( t) fcp ) J / ( phys ( ) CP ) ( phys ( ) CP ) Γ Γ Af ( t) = = S sin mt CP ψk S Γ t f +Γ t f Amplitue of CP asymmetry VV VV VV V Imλ = η Im Im J / ψk f = S CP VV VV VV V * * * * cs cb tb t cs c t * * * cs cb tb t cs c t = sin2β Quark subprocess mixing K mixing ~.7 instea of 2x1-3! 21

22 Experimental approach to CP violation in the meson system 22

23 Some reality Cross Section: 1nb = 1-33 cm -2 Reconstruct CP eigenstate with probability ~1-5 Was it a or anti-? tagging probability ~3% Luminosity target: 3 x 1 33 cm -2 s -1 3 Hz of events 1 year of ata logging = 3 tagge an reconstructe CP events 23

24 Complications from Quantum Mechanics ϒ(4 S) 1 + Initial state: prepare antisymmetric wave function View in e + e - centerof-mass frame e + ϒ ( 4S ) Then = ( t ) rec If = ( t ) tag 3µm e ( t) rec Unmeasurable istance! Consequence rec evolves inepenently as a function of t = t t 24

25 Use asymmetric- energy collisions! - e βγ ϒ (4 S ) =.56 t ϒ ( 4S ) z βγ 1 c rec + e tag z J / ψ z ~ 26µ m z µ + µ K S t is a signe quantity σ ~ 1 ps 17 µ m Start the clock t τ ~ 1.6 ps 25 µ m t measurement π + π Exclusive Meson & vertex reconstruction K -flavor tag & tag vertex reconstruction Tagging performance: Q = 3.5% 25

26 PEP- II Factory at SLAC + 9 GeV e 3.1 GeV e ϒ (4 S ) boost: βγ =.55 Hea - on collisions Locate at the SLAC National Accelerator Laboratory Operate from

27 KEK Factory at KEK + 8 GeV e 3.5 GeV e ϒ (4 S ) boost: βγ =.425 ± 11 mra crossing angle Locate in the 3 km Tristan tunnel at KEK Operate

28 PEP- II Collier KEK Collier Apr 11, 27 D.MacFarlane at Notre Dame 28

29 AAR etector DIRC (PID) 144 quartz bars 11 PMs e (9GeV) 1.5T solenoi EMC 658 CsI(Tl) crystals e + (3.1GeV) Drift Chamber 4 layers Instrumente Flux Return Iron / Resistive Plate Chambers or Limite Streamer Tubes (muon / neutral harons) Silicon Vertex Tracker 5 layers, ouble sie strips Collaboration foune in 1993 Detector commissione in

30 The AAR Collaboration 1 Countries 78 Institutions 55 Physicists Apr 11, 27 D.MacFarlane at Notre Dame 3

31 elle Detector Aug 5-7, 22 D.MacFarlane at SSI 22 31

32 Apr 11, 27 D.MacFarlane at Notre Dame 32

33 J ψk K S / S J /ψ Apr 11, 27 D.MacFarlane at Notre Dame 33

34 Flavor tag: b ce ν e Recoil + vertex separation = time ifference Apr 11, 27 D.MacFarlane at Notre Dame 34

35 Apr 11, 27 D.MacFarlane at Notre Dame 35

36 Main Variables for Reconstruction For exclusive reconstruction, two nearly uncorrelate * kinematic variables are use: Energysubstitute mass E = E E mes Resolutions * * beam 2 2 ( * ) ( * E ) = p ( E, p ), E beam * * * beam σ = σ + σ σ E beam E E 2 p σ = σ + σ σ mes beam p beam m Signal at E ~ Signal at m ES ~ m caniate (energy, 3-momentum) an beam energy in ϒ(4S) frame σ E σ m ES 1 4 MeV MeV/c * If σ E were zero, the variables woul be fully correlate; however, σ E is typically at least 5 times larger than σ beam an so ominates E 36

37 Example for Haronic Decays E [MeV] m ES signal region Signal Region : [ ] mes, E = m ± 3 σm ES,± 3σ Sieban Region : Define outsie signal region in orer to estimate backgrouns J/ψK S E E siebans m ES [GeV/c 2 ] 37

38 Flavor Eigenstate Neutral Sample Charm ecay moes D D π, D K π, K ρ, K π π π, K π π D K K * S + + π π, S π ecay moes F (*) D h + h + = π + ρ + a + 1 (,, ) ( F D ) 28% F ( D ) 12% ( ) 4.1% * J ψk K + π / ( ) Self-Tagging Moes AAR 81.3 fb 1 N tag = Purity = 84% N tag = 1757 Purity = 96% m ES [GeV/c 2 ] m ES [GeV/c 2 ] 38

39 Vertex an z Reconstruction 1. Reconstruct rec vertex from rec aughters 2. Reconstruct tag irection from rec vertex & momentum, beam spot, an ϒ(4S) momentum = pseuotrack 3. Reconstruct tag vertex from pseuotrack plus consistent set of tag tracks eam spot 4. Convert from Δz to Δt, accounting for (small) momentum in ϒ(4S) frame Interaction Point z rec vertex tag Vertex tag tracks, V s rec irection rec aughters tag irection Result: High efficiency (97%) an σ(δz) rms ~ 18μm versus < Δz > ~ βγcτ = 26μm 39

40 Methos for Flavor Tagging Many ifferent physics processes can be use Primary lepton Seconary lepton Kaon(s) Soft pions from D * ecays D ν + * D π +, D K + ν + DX, D K X D X D D π +, s Fast charge tracks + π + ρ +, W + W b c s K + 4

41 Tagging at AAR Sub-taggers 9 Tagging Categories Electron- K Muon- K Electrons Muons Kaon- π soft Kaon 1 π soft Kaon 2 Other 4 Physics Categories Lepton Kaon I Kaon II Inclusive Figure of merit for tagging Q = εd 2 41

42 Some Inputs to NN Tagger Sum of energy within 9 o of estimate W irection D + ν Opening angle between input track an missing momentum vector D + ν Opening angle between input track an thrust axis of recoil D D X + D π s, CMS momentum of input track D + ν 42

43 Flavor Tagging Performance in Data The large sample of fully reconstructe events provies the precise etermination of the tagging parameters require in the CP fit Tagging category Fraction of tagge events ε (%) Wrong tag fraction w (%) Mistag fraction ifference w (%) Q = ε (1-2w) 2 (%) Lepton 9. 1 ± ± ± ±. 3 Kaon I ± ± ± ±. 4 Kaon II ± ± ± ±. 4 Inclusive 2. ± ± ± ±. 2 ALL ± ±. 7 Highest efficiency Error on sin2β an m epen on the quality factor Q approx. as: 1 σ( sin 2β) Q Smallest mistag fraction AAR 81.3 fb 1 43

44 - Mixing Analysis: Time Distributions UnMixe Mixe perfect flavor tagging, time resolution Decay Time Difference (reco-tag) (ps) UnMixe Mixe realistic mistag probability, finite time resolution Decay Time Difference (reco-tag) (ps) Δt /τ Δt /τ e e f mixing, ± (Δt) f = mixing, ± (Δt) = ( 1 ± ( 1 2( 1ω± ) cos Δm Δt ) R( Δt ) 4τ 4τ "f " unmixe ( or ) mixing, + + flav tag fl flav tag "f " mixe ( or ) mixing, flav f tag fl fla avv tag ω R( t) is the flavor mistag probability is the time resolution function 44

45 Mixing with Haronic Sample Signal: m ES >5.27 gn: m ES <5.27 AAR 29.7 fb 1 Precision measurement consistent with worl average Δm = (. 516 ±. 16 ±. 1 ) ps 1 AAR PRL 88, (22) (stat) (syst) 45

46 Mixing Asymmetry with Haronic Sample Unfole raw asymmetry A mixing( t) 1 2 cosδm Δt ( ω ) Fole raw asymmetry t [ps] AAR 29.7 fb 1 ~ 1 2ω ~ π / m t [ps] 46

47 CP analysis: time istributions Perfect flavor tagging & time resolution Realistic mistag probability & finite time resolution tag tag tag tag Δt /τ Δt /τ e e f ( 1 ) CP, ± (Δt) = ( 1 ( 1 2 ) η sin f ) f CP, ± (Δt) = η ω 2β sin Δm Δt ( ) f R Δt 2τ 2τ "f " = CP, + CP, tag ""f f " = tag same mistag probability ω an time-resolution function R( t) 47

48 Time- Depenent CP Asymmetries Time-epenence of - mixing N(unmixe) N(mixe) Amixing ( t) = ( 1 2ω ) cosδm Δt N(unmixe) + N(mixe) Time-epenence of CP-violating asymmetry in J K CP / ψ S N(tag = ) N( = ) ACP ( t) = ( 1 2ω ) sin 2β sin Δm Δt N( = ) + N( = ) tag tag tag (Assuming no confusion of rec state) Use the large statistics flav ata sample to etermine the mistag probabilities an the parameters of the time-resolution function 48

49 Now classic results for sin2β ( cc ) KS ( CP o) moes ( cc ) KL ( CP even) moes AAR CONF-6/36 ( cc ) KS + ( cc ) KL sin2β = 71. ±.34 ±.19 C = A =.7 ±.28 ± fb on peak or 348 M pairs CP events (tagge signal) ELLE-CONF-647 J J / ψ only / ψks + KL sin2β = 642. ±.31 ±.17 C = A =.18 ±.21 ± fb on peak or 532 M pairs CP events (tagge signal) 49

50 Pure Gol: Lepton Tags Alone AAR 81 fb 1 22 tagge η f = -1 events 98% purity 3.3% mistag rate 2% better t resolution sin2β =. 79 ±. 11 5

51 Check null Control Sample at AAR Input flav sample to CP fit No asymmetry expecte Sample sin2β flav. 21 ± ±

52 CPV in charmonium moes η ( ρη, ) Γ( b u ν ) α = φ 2 - mixing (,) γ = φ 3 β = 1 φ τ an Γ ( b c ( 1, ) ν) Interference of b c tree ecay with mixing CPV in J / ψk S ρ b b W t t W c c J /ψ s W b K 52

53 CPV in charmless moes Γ( b u ν ) (,) η ( ρη, ) γ α = φ 3 = φ 2 β CPV in ππ ρπ ρρ,,, = 1 φ mixing - τ an Γ ( b c ( 1, ) ν) Interference of suppresse b u tree ecay with mixing ρ b 3 r component: sizable Penguin iagram b b W uct,, W t t g W u u u u W b π π + π π + 53

54 Remarkably goo progress on gamma! Γ( b u ν ) (,) η ( ρη, ) γ α = φ 3 = φ 2 γ : CPV in D K, D K, CP mixing - τ an Γ ( b c ( 1, ) ν) DCS Interference of color-allowe an color-suppresse tree ecays β = 1 φ ρ Effect epens on ratio of two iagrams b u b u W W u K (*) s c (*) D u u c s u D (*) (*) K +D( D) ecay to common final state DCP, DDCS, D KS π + π 54

55 Direct CP violation measurements sin2β α γ cos2β 55

56 Summary of UT triangle constraints Paraigm change! Now: looking for New Physics as correction to CKM 56

57 Continuing the hunt for new sources of CP violation 57

58 UT from CP violation measurements alone Factory milestone: Comparable UT precision from CPV in ecays alone Overconstraine: subsets of measurements can be use to test for new physics 58

59 CPV in Penguin Moes Γ( b u ν ) η ( ρη, ) α = φ 2 - mixing Another implication of overconstraine: reunant approaches to same CKM parameter (,) γ = φ 3 β = 1 τ an Γ ( b c ( 1, ) ν) Interference of suppresse b s Penguin ecay with mixing φ ρ CPV in φk, η K, b b W uct,, t t S g W S s s s W b K φ 59

60 Potential New Physics contributions φk + W New physics in loops? b u, c, t g Internal Penguin s s s φ K S b s s s φ K S η K SUSY contribution with new phases η η K S b s s s η K S 6

61 Is there New Physics in mixing? C e Introuce new physics in b mixing iagram SM ( M ) = C ( ) M ACP ( J / ψks ) = sin2( β + φ ) SM SM NP SM 2iϕ NP 2( i ϕ + ϕ ) 2i ϕ A e + A e = SM 2i ϕ A e SM Moel inepenent For relative phases >9 O coul easily have NP amplitues at 4% times SM Mass scale being probe for unit coupling: Λ(now) ~ 5 TeV Λ(28) ~ 1 TeV 61

62 Further bouns on New Physics Introuce new physics in b s mixing iagram Moel inepenent C e s SM SM NP SM 2iϕs NP 2( i ϕs + ϕs ) 2i ϕ s s s A e + A e = SM 2i ϕs A e SM s Coul easily have NP amplitues up to 3 times SM 62

63 Other winows on New Physics Examples of rare ecays with sensitivity to New Physics b u τν W,H τ ν b W ργ t γ New inepenent measurement of Vub New inepenent measurement of V / V t ts 63

64 CP Violation in mixing iagram CPV through interference of ecay amplitues CPV through interference between mixing an ecay amplitues CPV through interference of mixing iagram Resulting semileptonc charge asymmetry: a q Sl Γ = M q q tanφ q Expecte to be very small M 12 off-shell states f i Γ12 2 on-shell states f where M q, Γ q are mass & with ifferences for propagation matrices of neutral eigenstates φq CP violating phase 64

65 Asymmetry measurement from D Measurable: Like-sign imuon charge asymmetry: A N N ++ b bb bb Sl = ++ N + N bb bb D observes: = Ca + Ca s Sl s Sl Coefficients C, epen on impact parameter C s A = (.787 ±.172( stat) ±.93( syst))% b Sl versus Stanar Moel expectation: b ASl ( SM ) = (.28 )% (3.9σ ifference) V.M.Abazov, et al. (D Collab), FERMILA-PU E 65

66 Implications for new physics in mixing 66

67 A new era with Super Factories 67

68 Physics case for new Flavor Factories Flavor physics sensitive to processes that are one- loop in SM but coul be O(1 ) for NP o FCNC, mixing, CPV Current experimental boun is O(1-1 TeV) epening on NP coupling. o If the LHC fins NP at O(1 TeV) it must have a non-trivial flavor structure Even if no NP is iscovere at the LHC, current SM couplings provie sensitivity to NP at high mass scales 68

69 Physics opportunity with Super Flavor Factory x5-75 sample size 69

70 Revealing new physics effects in the flavor sector CKM matrix measures the relative orientation of the u an sector Yukawa couplings in the Stanar Moel In SUSY there are a new set of (moelepenent) Yukawa couplings escribing the squark an slepton sectors Minimal Flavor Violation (MFV), for example, is the assumption that the ol an new Yukawa couplings are aligne Mass insertion approximation allows us to set a moelinepenent scale for effects ( ij ) δ = A ( Δ ij ) m A 2 L R s L s R b L b R Flavor stuies etermine the off-iagonal (mixing) elements 7

71 Super Flavor Factory with 75 ab transitions 2-3 transitions β Δm A CP ( xγ s ) ( xγ ) s A sl ( x + ) s m = m = 1 TeV, ( δ ) =.85ei π q g 13 LL /4 m = m = 1 TeV, ( δ ) =.28ei π q g 23 LR /4 Complementary to iscovery opportunity with the LHC 71

72 Unraveling the nature of New Physics Nee to combine measurements to eluciate structure of new physics = Super can measure these moes More information on the golen matrix can be foun in arxiv: , arxiv: , an arxiv:

73 Next generation Super Factories Strong physics case for a 1 36 facility (x5): improve sensitivity by more than orer of magnitue New ieas: o Ultra low-emittance, similar to ILC amping rings o Scale version ILC final focus o Large crossing angle an crabbe waist Features: o Machine has significant technical overlap with ILC o Possible to reach 1 36 luminosity with beam currents comparable to present Factories allowing (re-)use of existing etectors an machine components Super layout 4x7 GeV 66 low-emittance mra electron-positron rings in common 2-3 km tunnel -- straight sections -- ipoles -- quarupoles -- sextupoles IP -- RF cavities Super -- solenois Factory 4.2 x 6.8 GeV collisions with 1 36 luminosity 1258m circumference

74 History of e + e - collier luminosity 1 35 Super Factories INP c-τ KEK Super SUPERKEK Linear colliers ILC Luminosity (cm -2 s -1 ) Factories DAΦNE VEPP2 VEPP-2M PEP-II EPCII CESR PEP CESR -c DORIS2 PETRA EPC VEPP-4M PETRA SPEAR2 LEP LEP LEP LEP CLIC 1 29 DCI ADONE 1 27 ADONE c.m. Energy (GeV) 74

75 Super at Tor Vergata, Italy Tor Vergata University campus Selecte site About 4.5 Km LNF

76 Upate on Flavor Physics Strategy 76

77 SuperKEK luminosity upgrae projection Integrate Luminosity (ab -1 ) We are here Goal of SuperKEK We will reach 5 ab -1 aroun month/year 2 ays/month Peak Luminosity (cm -2 s -1 ) Commissioning starts mi of 214 Shutown for upgrae Year 77

78 Origin of matter-antimatter asymmetry remains a funamental mystery: New roun of Super Factories is essential for exploring this frontier Apr 11, 27 D.MacFarlane at Notre Dame 78