12 Best Reasons to Like CP Violation

Transcription

1 12 Best Reasons to Like CP Violation SSI 2012 The Electroweak Scale: Unraveling the Mysteries at the LHC SLAC, California 27 July 2012 Yossi Nir (Weizmann Institute of Science) SSI40 1/35

2 CP Violation 1st REASON SSI40 2/35

3 CP Violation 1st REASON Otherwise we would not be here SSI40 2/35

4 Otherwise we would not be here The Baryon Asymmetry Y B n b n b s = (8.75 ± 0.23) Antimatter disappeared from the Universe: n b /s 0 Matter has survived: n b /s SSI40 3/35

5 Otherwise we would not be here Sakharov Conditions The baryon asymmetry can be dynamically generated ( baryogenesis ) provided that 1. Baryon number is violated; 2. CP and C are violated; 3. Departure from thermal equilibrium. If CP were not violated, neither matter nor antimatter would have survived SSI40 4/35

6 CP Violation 2nd REASON SSI40 5/35

7 CP Violation 2nd REASON A window to t universe < s SSI40 5/35

8 Window to t U < seconds SM B + L violation Q 1 L e L µ L τ Q 2 T = 0 Γ e 8π2 /g 2 T T EWPT Γ 250α 5 wt Q 3 Γ B+L violation > H for T EWPT < T < GeV Baryon number is no longer violated after t seconds Electroweak baryogenesis: t seconds Leptogenesis: t < seconds SSI40 6/35

9 CP Violation 3rd REASON SSI40 7/35

10 CP Violation 3rd REASON It proves the SM wrong SSI40 7/35

11 The SM is wrong SM CP violation CP violated within the SM only if J CP (m 2 t m 2 c)(m 2 t m 2 u)(m 2 c m 2 u) (m 2 b m 2 s)(m 2 b m 2 d)(m 2 s m 2 d) s 12 s 23 s 13 c 12 c 23 c 13 s δ 0 The baryon asymmetry is therefore proportional to J CP : ( nb n γ ) SM J CP T 12 c ( nb n γ ) obs 10 9 The KM mechanism cannot produce large enough baryon asymmetry = There must exist sources of CPV beyond the KM phase SSI40 8/35

12 The SM is wrong SM EWPT Need a strongly 1st-order PT V T>T c T c T<T c φ c φ SSI40 9/35

13 The SM is wrong SM EWPT Need a strongly 1st-order PT m H 126 GeV V T>T c V T>T c T c T c T<T c T<T c φ c φ φ ϕ : 0 v continuously and uniformly in space The B + L violating processes switch off slowly The baryon asymmetry is erased The SM EWPT is not of the right kind SSI40 9/35

14 CP Violation 4th REASON SSI40 10/35

15 CP Violation 4th REASON Theory preceding experiment SSI40 10/35

16 Theory preceding experiment 1928: Dirac s Equation Dirac wanted to understand the electron Special relativity + quantum mechanics = Dirac Equation: iγ ψ = mψ Two solutions: electron e and anti-electron e + CP SSI40 11/35

17 Theory preceding experiment 1932: Anderson s positron SSI40 12/35

18 CP Violation 5th REASON SSI40 13/35

19 CP Violation 5th REASON Experiment preceding theory SSI40 13/35

20 Experiment preceding theory 1964: CP is violated! If CP is a good symmetry: Mass eigenstates = CP eigenstates Two neutral kaon states: K S = K CP =+, K L = K CP = K S ππ, K L ππ 1964, Cronin and Fitch: Experimental discovery of K L ππ CPV SSI40 14/35

21 CP Violation 6th REASON SSI40 15/35

22 CP Violation 6th REASON Predicting the third generation SSI40 15/35

23 Predicting the third generation Kobayashi and Maskawa (I) CP violation Complex couplings: Hermiticity: L g ijk ϕ i ϕ j ϕ k + g ijk ϕ i ϕ j ϕ k CP transformation: ϕ i ϕ j ϕ k ϕ i ϕ j ϕ k CP is a good symmetry if g ijk = g ijk The number of real and imaginary quark flavor parameters: With two generations: 2 (4 R + 4 I ) [3 (1 R + 3 I ) 1 I ] = 5 R + 0 I With three generations: 2 (9 R + 9 I ) [3 (3 R + 6 I ) 1 I ] = 9 R + 1 I The two generation SM is CP conserving The three generation SM is CP violating SSI40 16/35

24 Predicting the third generation Kobayashi and Maskawa (II) A third generation is predicted to exist All flavor violation in V = The CKM matrix L W = g 2 U L V γ µ D L W µ + + h.c. V unitary with 3 real (λ, A, ρ) and 1 imaginary (η) parameters: 1 λ Aλ 3 (ρ + iη) V λ 1 Aλ 2 Aλ 3 (1 ρ + iη) Aλ 2 1 η - the only source of CP violation A very predictive theory of CP violation: Easily falsiable SSI40 17/35

25 CP Violation 7th REASON SSI40 18/35

26 CP Violation 7th REASON QCD is CP invariant SSI40 18/35

27 QCD is CP invariant S ψks B 0 ψk S B 0 Babar/Belle: A ψks (t) = dγ dt [B0 phys (t) ψk S] dγ dt [B0 phys (t) ψk S] dγ dt [B0 phys (t) ψk S]+ dγ dt [B0 phys (t) ψk S] Theory: A ψks (t) dominated by interference between A(B 0 ψk S ) and A(B 0 B 0 ψk S ) = A ψks (t) = S ψks sin( m B t) Babar/Belle: S ψks = 0.68 ± 0.02 SSI40 19/35

28 QCD is CP invariant S ψks in the SM S ψks = Im [ V tb V td V tb V td ] V cb V cd Vcb V cd = 2η(1 ρ) η 2 +(1 ρ) 2 = sin 2β All hadronic parameters cancel in A ψks (t) (and S ψks ) as a result of the CP invariance of QCD The approximations involved are better than one percent! Similar theoretical cleanliness in CPV observables: K πν ν, B DK SSI40 20/35

29 CP Violation 8th REASON SSI40 21/35

30 CP Violation 8th REASON QCD is not CP invariant SSI40 21/35

31 QCD is not CP invariant The θ QCD puzzle L θ = α s 8π θ QCDG µν a G aµν d n θ QCD e cm d exp n < e cm = θ QCD < PQ symmetry? Spontaneous CP violation? m u = 0? SSI40 22/35

32 CP Violation 9th REASON SSI40 23/35

33 CP Violation 9th REASON Richness of experimental results SSI40 23/35

34 Richness of experimental results A brief history ε = (2.228 ± 0.011) 10 3 ; Re(ε /ε) = (1.65 ± 0.26) 10 3 SSI40 24/35

35 Richness of experimental results A brief history ε = (2.228 ± 0.011) 10 3 ; Re(ε /ε) = (1.65 ± 0.26) S ψks = ± 0.02 S ϕks = ± 0.12, S η K S = ± 0.07, S f0 K S = ± 0.11 S K + K K S = ± 0.10 S π + π = 0.65 ± 0.07, C π + π = 0.36 ± 0.06 S ψπ 0 = 0.93 ± 0.15, S D + D = 0.98 ± 0.17, S D + D = 0.77 ± 0.10 A K π ± = ± A D+ K ± = ± 0.03 SSI40 24/35

36 CP Violation 10th REASON SSI40 25/35

37 CP Violation 10th REASON Beauty of theoretical methods SSI40 25/35

38 Beauty of theoretical methods Testing CKM Take I Assume: CKM matrix is the only source of FV and CPV = Four CKM parameters: λ, A, ρ, η λ known from K πlν A known from b clν Many observables are f(ρ, η): b ulν = V ub /V cb 2 ρ 2 + η 2 m Bd / m Bs = V td /V ts 2 (1 ρ) 2 + η 2 S ψks = 2η(1 ρ) (1 ρ) 2 +η 2 S ρρ (α) A DK (γ) ϵ K Beautiful theory: Isopsin, HQS, HQET, SCET... SSI40 26/35

39 Beauty of theoretical methods The B-factories Plot 1.5 excluded at CL > 0.95 excluded area has CL > 0.95 γ 1.0 m d & m s η sin 2β ε K α CKM f i t t e r Summer 11 V ub γ γ α β α m d ε K sol. w/ cos 2β < 0 (excl. at CL > 0.95) η excluded area has CL > 0.95 sin 2β ε K γ α ρ ε K CKM f i t t e r Summer 11 sol. w/ cos 2β < 0 (excl. at CL > 0.95) 0.1 α γ β α ρ Very likely, the CKM mechanism dominates FV and CPV SSI40 27/35

40 Beauty of theoretical methods Testing CKM - take II Assume: New Physics in leading tree decays - negligible Allow arbitrary new physics in loop processes Consider only tree decays and B 0 B 0 mixing Define h d e 2iσ d = A NP (B 0 B)/A SM (B 0 B) = Four parameters: ρ, η (CKM), h d, σ d (NP) Use V ub /V cb, A DK, S ψk, S ρρ, m Bd, A d SL Fit to η, ρ, h d, σ d Find whether η = 0 is allowed If not = The KM mechanism is at work Find whether h d 1 is allowed If not = The KM mechanism is dominant SSI40 28/35

41 Beauty of theoretical methods η 0? CKM 1-CL f i t t e r FPCP η γ α β ρ 0 The KM mechanism is at work SSI40 29/35

42 Beauty of theoretical methods h d 1? CKM 1-CL f i t t e r FPCP σ d h d 0 The KM mechanism dominates CP violation Complete alternatives (superweak, approximate CP) excluded The CKM mechanism is a major player in flavor violation SSI40 30/35

43 CP Violation 11th REASON SSI40 31/35

44 CP Violation 11th REASON Hints of new physics? SSI40 31/35

45 Hints of new physics? Charm, Bottom, Top anomalies LHCb+CDF+...: A CP = ( 0.66 ± 0.15) 10 2 SM(?): A CP < 10 3 D0: A b SL SM: A b SL = ( 7.9 ± 1.7 ± 0.9) 10 3 = ( 0.23 ± 0.06) 10 3 CDF+D0: Forward-backward asymmetry in t t production Observable Experiment SM A t FB 0.18 ± A l FB 0.15 ± A t FB (m t t > 450) 0.28 ± SSI40 32/35

46 CP Violation 12th REASON SSI40 33/35

47 CP Violation 12th REASON Otherwise I would not be here today SSI40 33/35

48 Otherwise I would not be here today SSI SSI 1992: CP violation SSI 1999: CP violation in and beyond the SM SSI 2010: Leptogenesis SSI40 34/35

49 CP violation SSI12: 12 best reasons to like CPV Otherwise we would not be here A window to the Univesre at t < second It proves the SM wrong CP: An example of theory preceding experiment CPV: An example of experiment preceding theory Predicting the third generation QCD is CP invariant QCD is not CP invariant Richness of experimental results Beauty of theoretical methods Hints of new physics? Otherwise I would not be here today SSI40 35/35

50 13th reason A book SSI40 36/35

51 14th reason Nobel festivities SSI40 37/35