b s Hadronic Decays at Belle

Transcription

1 b s Hadronic Decays at Belle Sunghyon Kyeong Yonsei University, Seoul, Korea (on Behalf of the Belle Collaboration Europhysics Conference on High Energy Physics Kraków, Poland, 16- July, 9 sunghyon.kyeong@gmail.com

2 INTRODUCTION In the Standard Model (SM, Charmless hadronic B decays occur mainly via two processes. (i b s penguin diagram (ii b u tree diagram Charmless hadronic B-decays give us plenty of information. * Search for new physics effects by studying loop processes. * b s quark transitions are sensitive to physics beyond SM. * Direct CP Violation : Interefering SM amplitudes. * Measuring BF, angular correlations could help the phenomenological test/development of the theoretical models. Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 /

3 MOTIVATION * Measurements of f L in rare B decays to VV, such as B φk, have revealed an unexpectedly large fraction of transverse polarisation. * This implies that non-factorizable contributions to the decay amplitude play a significant role. * Further information about these effects can be obtained with B and f L in B ρ K (also b s penguin-dominated. BaBar s Results, PRL 97, 181, (6 with B B Mode Y ε S B f L (events (% (σ (1 6 ρ K 18± ±.9±1.3.7±.9±.8 f (98K 83± ±.6±.9 Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 3 /

4 KEKB AND BELLE DETECTOR - Ring circumference of KEKB is approximately 3. km. - KEKB has two separate rings for e + and e. * located at energy asymmetric e + e collider KEKB. * Belle detactor has a large-solid-angle magnetic spectrometer, providing excellent tracking, vertexing and PID. Approximately.8 billion B B pairs recorded at Belle! Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 4 /

5 ANALYSIS METHOD * Recontruction Variables: - E = E B E beam : Energy difference - M bc = Ebeam P B : Beam-energy constrained mass - Invariant masses of ππ and K π (i.e. M ππ and M K π * Continuum (e + e q q Suppression: - Modified Fox-Wolfram moments, B flight direction (cos θ B, and the decay vertex differences between the signal B and that of the other B in z direction ( z. - Perform Figure of Merit study to get a continuum suppression cut value. * Veto B D ± X, D ± X, D X modes Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 /

6 YIELD EXTRACTION BY 4-D FIT 4-D Extended Unbinned ML Function: ( exp j Y N j cand ( L = Y j P i j N! where, P i j = P j (Mbc i P j( E i P j (MππP i j (MK i π, for component j, and i runs over all events in the sample. For Signal PDFs: where, f SCF is the SCF fraction. i=1 j (1 P i j = (1 f SCF P i true + f SCF P i SCF ( Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 6 /

7 Submitted to PRL arxiv:9.763v1 Measurements of B ρ K and B π + π K + π using a sample of 67 million B B pairs

8 SIGNAL MC DISTRIBUTIONS 1. M Kπ M Kπ M Kπ M ππ M ππ M ππ ρ K f (98K π + π K M Kπ 1. M Kπ 1. M Kπ M ππ M ππ M ππ ρ K + π f (98K + π π + π K + π Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 8 /

9 BKG. MC DISTRIBUTIONS * Continuum (e + e q q. χ / ndf = 1.79 χ / ndf =.91 χ / ndf = 14.6 Events / MeV/c Events / 8MeV Events / 6MeV/c χ / ndf = 1. Events / 18MeV/c M (GeV/c bc E (GeV M ππ (GeV/c M (GeV/c Kπ * Charmed B-decays (b c. Events / MeV/c Events / 8MeV Events / 6MeV/c Events / 18MeV/c M (GeV/c bc E (GeV M ππ (GeV/c M (GeV/c Kπ * Charmless B-decays (b s, u, d, B f (17K, and feeddowns B a 1 (16K +, B K + 1 (17π and B K + 1 (14π are also considered. Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 9 /

10 4D FITTING PROJECTION Events / MeV/c (a Events / 8MeV 6 (b M bc (GeV/c E (GeV Events / 6MeV/c (c M ππ (GeV/c Events / 18MeV/c (d M Kπ (GeV/c Projection of the 4D fit results on to (a M bc, (b E, (c M ππ and (d M K π with the other variables required to be the signal criteria (except for the variable plotted. The curves are for the ρ K + π (solid-shaded, the sum of ρ K and f (98K (dashed, the sum of backgrounds (dotted, and the total (solid. Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 1 /

11 FITTING RESULTS Mode Y ε S B B UL (events (% (σ (1 6 (1 6 ρ K < 3.4 f (98K <. ρ K + π ±. ±. - f (98K + π ± <.1 π + π K π + π K + π <.1 B and B UL of the non-resonant decay are partial one for the ranges: M ππ (., 1. GeV/c and M K π (.7, 1. GeV/c Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 11 /

12 ADDITIVE SYST. ERRROR Source ρk f K ρk π f K π ππk ππk π +4.4 Fitting PDFs f f (17K f feed down f b s,u,d f SCF.1 K +9. (143 Fitting bias Interference Sum (events Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 1 /

13 MULTIPLICATIVE SYST. ERROR Source ρk f K ρk π f K π ππk ππk π MC statistics ±. ±.7 ±1.3 ±1.7 ±1.3 ±.1 Tracking ±4. ±4. ±4. ±4. ±4. ±4. PID ±3.7 ±3.7 ±3.7 ±3.8 ±3.8 ±3.7 R q q cut ±3.4 ±3.4 ±3.4 ±3.4 ±3.4 ±3.4 N B B ±1.4 ±1.4 ±1.4 ±1.4 ±1.4 ±1.4 f L Sum (% ±6.7 ±6.8 ±7. ±6.9 ±7. Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 13 /

14 SUMMARY * The first observation of the three-body decay B ρ K + π decay with.σ significance. * The first evidences for non-resonant B f (98K + π and B π + π K decays. * 9% C.L. upper limit for the fully non-resonant four-body decay B π + π K + π is calculated. * B and B UL of non-resonant decay are partial one for the ranges :. < M ππ < 1. and.7 < M K π < 1.. * Signal excesses for the two-body decays B f (98K and B ρ K. * More data set could help our understanding of the polarization puzzle in the ρk and new physics effect on B VV decays.

15 BACKUP SLIDES

16 CONTROL SAMPLE STUDY We study the B D (K + π π π + as our control sample. We perform D (M bc and E unbinned ML fit. We assume our control sample can be categorized into three components: B D (K πππ + signal, peaking background, and other non-resonant background. 8 7 Events / 3.6MeV/c Events / 16MeV M bc (GeV/c E (GeV B of our control sample is consistent with the PDG value. Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 16 /

17 FITTING BIAS B ρ K χ / ndf / 9 y-axis 8.41 ± slope.988 ± χ / ndf / 3 constant 7.6 ±.8 fitted Yields fitted Yields - No. of input * No. of input (ρ K * No. of input (ρ K B f (98K 1 χ / ndf 7.3 / 9 y-axis.731 ± 1.4 slope.986 ± χ / ndf 8 / 3 constant ±.74 fitted Yields fitted Yields - No. of input * No. of input (f K * No. of input (f K Fitting biases are considered as the systematics uncertainty. Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 17 /

18 TOY MC STUDY (I Events / (.1 4 µ = ±.38 σ =.997 ± Events / ( µ = 79.6 ± 1.1 σ = 9.7 ±.8 Events / ( µ = ±.4 σ = 1.66 ±.9 Events / ( µ = 3.68 ±.4 σ = 1.48 ± * Pull (ρ K * No. of fitting events (ρ K * Negative Error (ρ K * Positive Error (ρ K µ = ±.38 σ = 1.1 ±.7 4 µ =. ±.76 σ =. ± µ = ±.41 σ = 1.69 ±.9 µ =.48 ±.39 σ = 1.4 ±.8 Events / ( Events / (. 3 1 Events / ( Events / ( * Pull (f K * No. of fitting events (f K * Negative Error (f K * Positive Error (f K The definition of pull for contribution j is defined as pull(y j = Y j fit Y true j σ fit j Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 18 /

19 TOY MC STUDY (II Events / (.1 4 µ =.3 ±.39 σ = 1.14 ± Events / ( µ = 33 ± 18 σ = 479 ± Events / ( µ = ±. σ = 8.6 ± 1.6 Events / ( µ = 49.3 ±. σ =.8 ± Pull (qq No. of fitting events (qq Negative Error (qq Positive Error (qq 4 µ = -.14 ±.39 σ = 1.4 ±.8 4 µ = 48 ± 18 σ = 483 ± 13 4 µ = ±. σ =.1 ± µ = 449. ±. σ = 7.7 ± 1.6 Events / ( Events / ( Events / (. 3 1 Events / ( Pull (b c No. of fitting events (b c Negative Error (b c Positive Error (b c Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 19 /

20 BKG.-SUBTRACTED FIT Events / MeV/c (GeV/c M ππ Events / MeV/c (GeV/c M Kπ Figures show the yields obtained from the D M bc E fitting results as function of M ππ (left and M K π (right. Solid curves show the results of the fit and dashed lines indicates the non-resonant ππ (left and the non-resonant K π plus K (143 (right. The regions between the reddish straight lines show the nominal four-dimensional fit regions. Sunghyon Kyeong (Yonsei Univ. b s Hadronic Decay at Belle July 16-, 9 /