CP Violation in B Decays at BABAR

Transcription

1 CP Violation in B Decays at BABAR October 19-, 11 October 19-, 11 CP Violation in B Decays at BABAR (page 1

2 B Meson Factories BABAR at SLAC National Accelerator Laboratory, California, USA Another B-factory machine is at KEKB (Tskba in Japan October 19-, 11 CP Violation in B Decays at BABAR (page

3 BABAR Detector Collides (9 GeV e e (3.1 GeV Υ (4S with E CM = 1.58 GeV Peak lminosity : cm s 1, B B prodction 1 Hz Boost βγ =.56 allows to measre B decay times October 19-, 11 CP Violation in B Decays at BABAR (page 3

4 BABAR Data: Υ (ns Final BABAR Data CLEO October 19-, 11 CP Violation in B Decays at BABAR (page 4

5 CKM Matrix In SM, qark can change flavor by weak interactions: d s = b V d V s V b V cd V cs V cb V td V ts V tb d s b Cabibbo-Kobayashi-Maskawa (CKM matrix [Weak eigenstates] = [V CKM ] [qark mass eigenstates] The CKM matrix contains complex nmbers Wolfenstein s CKM matrix form: V CKM = 1 1 λ λ Aλ 3 (ρ iη λ 1 1 λ Aλ Aλ 3 (1 ρ iη Aλ 1 λ. (expansion parameter A, ρ, and η can be measred in B decays October 19-, 11 CP Violation in B Decays at BABAR (page 5

6 Unitarity Triangle (UT By applying the Unitarity condition (scalar prodct of any two rows or colmns: V b V d V cb V cd V tb V td = CKM matrix can be presented in the complex plane Unitarity Triangle (UT b l ν B - π π B B mixing B ργ V V B S ρk S B D cp K B ππ, Κπ d b V cd Vcb * It is very important to measre the CKM angles and its sides! * γ α b V V * cl ν td tb β B ψk S We need to measre them precisely in order to search for New Physics Deviation from the Standard Model will signal New Physics! October 19-, 11 CP Violation in B Decays at BABAR (page 6

7 Stats of UT Triangle η exclded area has CL >.95 sin β ε K α CKM f i t t e r ICHEP 1 V b γ γ γ α exclded at CL >.95 ρ β α & m s m d m d ε K sol. w/ cos β < (excl. at CL > Constraints in the ρ η plane η exclded area has CL >.95 sin β α ε K γ m d γ α & m s m d ρ V b ε K β CKM f i t t e r ICHEP 1 sol. w/ cos β < (excl. at CL > Zoomed constraints in the ρ η plane α Precision β 1 o Precision α 4 o Precision γ 14 o October 19-, 11 CP Violation in B Decays at BABAR (page 7

8 Measring Angle γ Interference between b cūs and b cs tree amplitdes B b c s D K B b cūs transition: B D K b s D K B b s c K D b cs transition: B D K B b s D K GLW: Cabibbo-sppressed D CP-eigenstates (K K, π π Grona, London, Wyler: PLB 53, 1991 & PLB 65, 1991 ADS: D Cabibbo-favored and dobly-cabibbo-sppressed (K ± π Atwood, Dnietz, Soni: PRL 78, 357, 1997 GGSZ: Cabibbo-favored D self-conjgate (Ks π π, Ks K K Giri, Grossman, Soffer, Zpan: PRD , 3 time limited October 19-, 11 CP Violation in B Decays at BABAR (page 8

9 GLW BABAR Contine... PRD 8 74, 1 Using BABAR Data: 45 fb 1 (467 M BB A CP =.5 ±.6 ±. A CP =.9 ±.7 ±. R CP = 1.18 ±.9 ±.5 R CP = 1.7 ±.8 ±.4 Direct CP-Violation on B ± DK ± : A CP at 3.6σ from zero 1-CL % 95% γ [ ] 1-CL % 95% r B At 68% CL: angle γ mod 18 o belongs to one of the three intervals: (11.3,.7 o, (8.8 o, 99. o, (157 o, o At 68% CL:.4 < r B <.45 October 19-, 11 CP Violation in B Decays at BABAR (page 9

10 ADS on B ± DK ± Theory: PRL 78, 357, 1997 In ADS method (D. Atwood, I Dnietz, A Soni B D K D K π [dobly-cabbibo-sppressed] (interferes with B D K D K π [Cabbibo-favored] = Opposite-sign (OS becase two kaons have opposite charges Define same-sign (SS events: B D K D K π [Cabbibo-favored] BABAR pblished reslts where D are reconstrcted: D K π ; Data: BB PRD 8 76, 1 D K π π ; Data: BB PRD 84 1, 11 October 19-, 11 CP Violation in B Decays at BABAR (page 1

11 ADS Reslts on D K π PRD 8 76, 1 Simltaneos fit to m ES and NN (event shape and tagging variables Events/(.5 MeV/c (a Events / ( (d m ES (GeV/c NN m ES : opposite-sign B D K NN: opposite-sign B D K Solid-ble: Fll PDF, Red: sm of all bkgs, Dotted-ble: qq backgrond ADS B ± DK ± reslts: R = (. ±.9 ±.3 1 R = (. ±.6 ±. 1 October 19-, 11 CP Violation in B Decays at BABAR (page 11

12 ADS BABAR Reslts Contine... This measrement allowed s to extract variables: r B and γ 1- confidence level D K - D* K 1- confidence level σ σ...1 σ r (* B.1 σ γ (deg Constraints on r ( B : B D ( K C.L. crve as a fnction of γ For γ reslt: combining B DK and D K The variables r ( B can be extracted: r B = ( % r B = ( % October 19-, 11 CP Violation in B Decays at BABAR (page 1

13 ADS Reslts on D K π π PRD 84 1, 11 (NEW Simltaneos fit to m ES and Fisher: OS events; SS events Events/(1.8 MeV/c 1 (a m ES (GeV/c Events/(18 MeV/c 3 Fll 1 signal BB peak BB non-peak continm m ES (GeV/c m ES : opposite-sign with F >.5 m ES : same-sign with F >.5 Events / ( (c Events / ( (d - Fisher - Fisher Fisher: OS m ES >.7 GeV/c Fisher: SS m ES >.7 GeV/c October 19-, 11 CP Violation in B Decays at BABAR (page 13

14 ADS Reslts on D K π π PRD 84 1, 11 (NEW ADS reslts on r B : Probability density Bayesian probability density fnction for r B Dark:.1 < r B <.11 at 68% probability Light: r B <.13 at 9% probability Sbject to small r B, this measrement has less precision for γ reslt New reslts on R and R (statistical limited: r B R = ( R = ( At 9% probability limit: R < R < October 19-, 11 CP Violation in B Decays at BABAR (page 14

15 Smmary BABAR reslts provide increased constraints on CP Violation in B 1..8 CKM f i t t e r ICHEP 1 D(* K(* GLW ADS D(* K(* GGSZ Fll Freqentist treatment on MC basis WA γ = ( o Combined CKM fit CKMfitter Grop, ICHEP CL.6.4 New reslts from BABAR on ADS γ (deg D K π π, PRD 84 1, 11 BABAR reslts on ADS D K π, PRD 8 76, 1 BABAR reslts on GLW Model PRD 8 74, 1 BABAR also contribtes significantly on R, R, and r B October 19-, 11 CP Violation in B Decays at BABAR (page 15

16 BACKUP GLW on B ± DK ± PLB 53, 1991 & PLB 65, 1991 In GLW method the D mesons are reconstrcted: CP : D K K, π π CP : D K s π, K s ω, K s φ D CP ± = CP eigenstates of D system Two direct CP-violating partial decay rate asymmetries: A CP ± Γ(B D CP ± K Γ(B D CP ± K Γ(B D CP ± K Γ(B D CP ± K Γ = partial decay width Two ratios of charged averaged partial rates: R CP ± Γ(B D CP ± K Γ(B D CP ± K Γ(B D K Γ(B D K Then γ can be extracted from the other two nknowns variables δ B and r B : R CP ± = 1 r B ± r Bcosδ B cosγ A CP ± = ±r Bsinδ B sinγ 1r B ±r Bcosδ B cosγ δ B = the difference of their strong phases r B = the magnitde of the ratio of the amplitdes for each decay r B A(B D K A(B D K October 19-, 11 CP Violation in B Decays at BABAR (page 16

17 GLW BABAR Reslts PRD 8 74, 1 ML fit to E, m ES, and Fisher (event shape variable Events / (.1 GeV a - - B DK -, D K K - D π π Events / (.1 GeV b B DK -, D K K - D π π Events / (.8 GeV/c a - - B DK -, D K K - D π π Events / (.8 GeV/c b B DK -, D K K - D π π E (GeV CP : E E (GeV (GeV/c m ES CP : m ES (GeV/c m ES Events / (.1 GeV c B DK 4 35 D KS π, 3 D KS ω, 5 D KS φ E (GeV Events / (.1 GeV CP : E d B DK D K S π, D KS ω, D K S φ E (GeV Events / (.8 GeV/c c - - B DK D K S π, D KS ω, D K S φ (GeV/c m ES Events / (.8 GeV/c d B DK D K S π, D KS ω, D K S φ (GeV/c CP : m ES GLW: Cabibbo-sppressed D CP-eigenstates (K K, π π Grona, London, Wyler: PLB 53, 1991 & PLB 65, 1991 Ble line: fll PDF, Green: B Dπ, Prple: remaining backgronds B DK contribtion: the region between ble and green m ES October 19-, 11 CP Violation in B Decays at BABAR (page 17

18 ADS on B ± DK ± Contine... Extract new set of variables: R = Γ(B [K π ]K Γ(B [K π ]K opposite sign yield same sign yield from B R = Γ(B [K π ]K Γ(B [K π ]K opposite sign yield same sign yield from B Neglecting D-mixing effects the ratios R and R can be written as R = r B r D r Br D k D cos(γ δ B δ D R = r B r D r Br D k D cos(γ δ B δ D where r B A(B D K A(B D K =.16 ±.16 r D = Γ(D K π Γ(D K π = (.± δ B and δ D = ( o are CP conserving strong phase γ is CP violating weak phase k D is the coherence factor between to 1: k D =.84 ±.7 k D and δ D were measred from CLEOc October 19-, 11 CP Violation in B Decays at BABAR (page 18