Sin2β and Cos2β from b ccd and b cud transitions at BABAR

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1 Sin2β and Cos2β from b ccd and b cud transitions at BABAR Alessandro Gaz University & INFN Padova on behalf of the BABAR Collaboration 4th International Workshop on the CKM Unitarity Triangle December Nagoya, Japan

2 Outline _ sin2β from b ccd transitions: B J/ψ π B D(*)+ D(*) _ sin2β and cos2β from b cud: B D(*) h Conclusions ; Dec 14th 26 2

3 B J/ψ π _ SU(3) related to B (cc)k ; Same weak_ phase as B (cc)k Different weak phase in dominant penguin SM prediction: S - sin2β C Fundamental to constrain possible deviations of SCP from sin2β in golden modes ; Dec 14th 26 M. Ciuchini, M. Pierini and L. Silvestrini, PRL 95, (25) see talk by M. Ciuchini at WG5 13 PM2 3

4 B J/ψ π 232 million BB pairs PRD RC 74, 3111 Use the following modes: B J/ψ π J/ψ e+e, µ+µ ; π γγ Continuum background suppressed through topological variables combined into a Fisher discriminant ; B J/ψ ΚS (ΚS ππ) separately studied; B flavor tagging efficiency: Q = εd2 = (3.5 ±.4)% Dec 14th 26 4

5 B J/ψ π 232 million BB pairs The unbinned ML fit yields 19 ± 12 signal events; BR(B J/ψ π ) = (1.94 ±.22 ±.17) x 1 5 B tagged events B tagged events C =.21 ±.26 ±.6 S =.68 ±.3 ±.4 Results well compatible with SM expectations Dec 14th 26 5

6 B J/ψ π Summer 26 state of the art: 6.7% CL contours for 2 dof Dec 14th 26 6

7 B D (*)+ D (*)- D(*) B D(*)+ B D(*) D(*)+ Branching fractions ~ ; Time dependent analysis sensitive to sin2β, but penguin pollution expected to be at the % level ; Z.Z. Xing, Direct CP violation possible up to 3% level ; Two different BaBar pubblications: Dec 14th 26 Phys. Rev. D 61, 141 (2) B D(*) D PRL 95, (25) B D*+ D* PRL 95, (25) 7

8 (*) B D D Neglecting penguin contribution: B D+ D B D* D (not CP eigenstate!) δ = difference in the strong phases between B D*+ Dand B D*- D+ General belief: δ is 'small' Dec 14th 26 8

9 (*) B D D 232 million BB pairs D*+ Dπ+ ; D K-π+, K-π+π, K-π+π-π+, KSπ+πD+ K-π+π+, (KSπ+ only in B D* D ) L mass : likelihood variable constructed from differences between reconstructed and nominal masses B D*+ D- B D*- D+ B D+ D- Signal purities are enhanced by cutting on L Dec 14th 26 mass and E 9

10 (*) B D B D*+ D- B D*- D+ D B D+ D- 232 million BB pairs B tagged B tagged asymmetry SD*+ D- =.54 ±.35 ±.7 CD*+ D- =.9 ±.25 ±.6 SD*- D+ =.29 ±.33 ±.7 CD*- D+ =.17 ±.24 ±.4 Dec 14th 26 SD+ D- =.29 ±.63 ±.6 CD+ D- =.11 ±.35 ±.6 1

11 *+ B D D *- CP even and CP odd contributions: Transversity basis, three amplitudes: A, A (CP even) need angular analysis to separate them! D*+ Dπ+, D*+ D+π but not (D+π, D π) D K-π+, K-π+π, K-π+π-π+, KSπ+π 232 million BB pairs and A (CP odd) D+ K-π+π+, KSπ+, K-K+π+ Fit to mes and cosθtr to measure the fraction of CP odd decays before the nominal fit to CP asymmetries: R =.125 ±.44 ± ± 28 signal events Signal purities are enhanced by cutting on Lmass and E, separately for each decay mode Dec 14th 26 11

12 *+ B D D *- 232 million BB pairs Time dependent CP asymmetries extracted from an unbinned ML fit to mes, cosθtrand t where the three transversity components are allowed to have different CP parameters; + : average of the CP even components : CP odd component C+ =.6 ±.17 ±.3 C =.2 ±.96 ±.11 S+ =.75 ±.25 ±.3 S = 1.75 ± 1.78 ±.22 Constraining the three components to have the same CP asymmetry: C =.3 ±.13 ±.2 S =.69 ±.23 ±.3 Dec 14th 26 12

13 B D Dec 14th 26 (*)+ D (*)- 13

14 B D* ( ) h Method proposed in: A. Bondar, T. Gershon and P. Krokovny Phys. Lett. B 624, 1 (25) h = π, η, η', ω _ ( ) _ ( ) (D* Dπ) _ ( ) D KSπ+π Dalitz analysis of D decays: strong phase variation along the plane allows the measurement of cos2β, thus reducing the 4 fold ambiguity on β _ as given by B (cc)k to a 2 fold ambiguity; +: B _ tagged : B tagged in general Dec 14th 26 Measure sin2β and cos2β as independent parameters 14

15 B D* h ( ) 311 million BB pairs Results presented at ICHEP 26 (hep ex/6715): Use the following modes: π γγ ; η γγ, π+π π ; η' π+π η ; ω π+π π Isobar Dalitz Plot model: same model used in γ analysis from B D(*)K(*)± Parameters are determined from a large sample of D*+ Dπ+ Continuum background suppressed through a Fisher discriminant exploiting event topology; Fake D Dalitz distributions are modeled by using md sidebands; Simultaneous fit to mes, md, t and Dalitz variables; Dec 14th 26 15

16 B D* h D π D η,η' D ω D* π, η ( ) D π D ω 311 million BB pairs D η,η' D* π, η Peaking background estimated from simulation Dec 14th 26 16

17 B D* h B tagged ( ) _ B tagged 311 million BB pairs mes sideband B tagged _ B tagged Dec 14th 26 17

18 B D* h ( ) 311 million BB pairs Fit results. Errors: statistical, exp. systematic, Dalitz plot model Constraining sin2β to.685: Generate 3 toy experiments with sin2β = sin2βwa and h cos2β = ±(1 sin22β)½ and fit leaving cos2β as the only free parameter h+ Fit distributions of the two samples with two Gaussian functions: h+(cos2β) and h (cos2β) Positive solution is favored at 87% C.L. Dec 14th 26 h+/(h+ + h ) =.87 for cos2β =.55 syst. error 18

19 B Dec 14th 26 D* ( ) h 19

20 Conclusions Intense experimental activity on b ccd and b cud transitions at BABAR; Excluded large deviations from SM in investigated modes; Each measurement is limited by statistics, expect significant improvements with final dataset; Positive cos2β solutions favored by B D(*) h ; Stronger evidence considering also Belle's result and other channels: see K. George's talk at WG5 13 PM2 Dec 14th 26 2

21 Backup slides Dec 14th 26 21

22 B J/ψ π M. Ciuchini, M. Pierini and L. Silvestrini, PRL 95, (25) Constraining the SCP difference from sin2β in golden modes: Assuming SU(3)... Fit to experimental observables to constrain S = SCP(J/ψK) sin2β correlation in B J/ψ π S =. ±.12 uncertainty comparable to experimental systematics! Better experimental precision needed to further constrain S. Dec 14th 26 22

23 B J/ψ π Systematics Dec 14th 26 23

24 B + ** D D Transversity basis: D*+ momenta in the D*+ rest frame D* momenta in the B rest frame Dec 14th 26 24

25 B Dec 14th 26 + ** D D 25

26 B D* ( ) h where: defining the Lorentz invariant variables: Dec 14th 26 26

27 B Splitted fit results Dec 14th 26 D* ( ) h Systematics 27

28 B D* ( ) h Dalitz Plot Model Dec 14th 26 28