Search for b → u transitions in B+ → {Kpp0}DK+ Denis Derkach and Achille Stocchi BaBar-France meeting Orsay, 17.01.2010

Outlook ADS study of B+→D0(D0)K+ , D0 →K-p+p0 selection; likelihood fit validation; rB extraction.

CKM angle g Wolfenstein parameterization l~0.22 A~0.8 r~0.16 h~0.34

g measurement g = 88° ± 16° ([41,123] @ 95% Prob.) g = -92° ± 16° ([-139,-57] @ 95% Prob.) ADS: D. Atwood, I. Dunietz, A. Soni Phys.Rev.Lett. 78 (1997) 3257 GLW: M. Gronau, D. London Phys.Lett.B253:483-488,1991. M. Gronau, D. Wyler Phys.Lett.B265:172-176,1991 Dalitz: A. Giri, Yu. Grossman, A. Soffer and J. Zupan,{Phys. Rev.} D68, 054018 (2003)

Current Situation (B+→DK+)

{ { { { } B+→DK+ system } } D g+dB “Vcb” channel “Vub” channel Vus u Vcs s D B+ K+ u u u Relative phase g+dB u c { b } { c Vub Vcs u b Vcb B+ u u B+ Vus } s K+ u K+ s u u

Idea of the ADS method Opposite sign events (os) Vcb B+ →D0K+ D0 →f B+ DCS Vcb B+ →D0K+ D0 →f B+ B+ →[K- p+p0]D0 K+ D0 →f B+→D0K+ Vub CA for f=K+p-p0 CA Vcb B+ →D0K+ D0 →f B+ B+ →[K+ p-p0]D0 K+ D0 →f B+ →D0K+ Vub DCS Same sign events (ss)

D→ multibody state CLEO-C, arXiv:1001.1840v1

Observables Good sensitivity to rB Allows to extract more Hard to measure AADS Allows to extract more information but DR+>DRADS

Selection Last analysis was performed with R14 on runs 1-4 205 fb-1 (Phys.Rev.D76:111101,2007) This analysis: R24 BchToD0KAll skim is used. Runs 1-6 with 428 fb-1. |DEB|<23 MeV 0.12 GeV/c2<Mp0<0.146 GeV/c2 |dM - dMPDG|< 0.024 GeV/c2 |cos(QBcm)|<0.8 K very tight Selection criteria optimization was performed for os simulated events The only source of peaking background found is This peaking background is essential only in same sign channel.

Continuum background rejection After extensive studies of NN and Fisher we have decided to use Fisher discriminant constructed of 6 variables to reject the continuum background. The optimization was done using TMVA 4.0.3 Variables used: L10 L12 |cos(qthrust)| cosine between B thrust axis and thrust axis of the rest of the event |Dt| proper time interval between B decays DOCA distance of closest approach between two tracks forming B meson DistB-D distance between B and D vertices } os polar moments ss

Efficiency Tables (os) Selection criteria signal B+B- B0B0 cc uds s (os) preselection 92,1 13690 4763 304385 256273 0,12 |DEB|<23 MeV 70,0 3429 1198 75923 63291 0,18 0.12 GeV/c2<Mp0<0.146 GeV/c2 65,8 2331 811 55274 45442 0,20 |dM - dMPDG|< 0.024 GeV/c2 57,8 1416 505 36537 27557 0,22 |cos(QBcm)|<0.8 54,4 1177 413 29520 22178 0,23 K very tight 37,2 369 99 14712 6506 0,24 mES>5.27 GeV/c2 37,1 71 21 2016 1014 0,49 Fisher>0 31,5 58 20 445 166 0,59 ss signal reconstruction efficiency ~ 9.7%

Efficiency Tables (ss) Selection criteria signal B+B- B0B0 cc uds Dp s (ss) preselection 6165 22949 8180 206176 195072 16349 9 |DEB|<23 MeV 4703 5394 2015 51711 48243 3579 14 0.12 GeV/c2<Mp0<0.146 GeV/c2 4412 3646 1380 36832 34716 2850 15 |dM - dMPDG|< 0.024 GeV/c2 3883 2294 844 23621 21060 2266 17 |cos(QBcm)|<0.8 3667 1933 698 19076 16884 2103 K very tight 2492 340 121 4322 3146 176 24 mES>5.27 GeV/c2 2489 135 44 584 460 160 40 Fisher>0 2127 111 38 124 82 130 42 ss signal reconstruction efficiency ~ 9.5%

Likelihood Fit Structure Extended MLL fit to (mES, Fisher) for the ss and os components Species: os signal; ss signal; os BB combinatorial background; ss BB combinatorial background; os continuum background; ss continuum background; ss peaking background. Same PDF parameterization Npeak is fixed in the fit from MC Nsig,tot=Nos,sig+Nss,sig Fitted: RADS, Nsig,tot NBB,os, NBB,ss Ncont,os, N cont, ss (Shape cont)os, (Shape cont)ss is fitted directly to avoid systematics.

Parameterization from MC (os) signal Double Bifurcated Gaussian Double Bifurcated Gaussian BB background Crystal Ball Double Gaussian continuum background ARGUS Triple Gaussian

Parameterization from MC (os) signal Double Bifurcated Gaussian Double Bifurcated Gaussian BB background Crystal Ball Double Gaussian continuum background ARGUS Triple Gaussian

Parameterization from MC (ss) signal Double Bifurcated Gaussian Double Bifurcated Gaussian Peaking background BB background Crystal Ball Double Bifurcated Gaussian continuum background ARGUS Double Gaussian

Parameterization from MC (ss) signal Double Bifurcated Gaussian Double Bifurcated Gaussian Peaking background BB background Crystal Ball Double Bifurcated Gaussian continuum background ARGUS Double Gaussian

Parameterizations from Data We use the control sample B+→D0p+, D0 →K+p-p0 to get the “signal” mES parameterization. We use the 44 fb-1 of off-resonance data to get the “continuum” Fisher parameterization.

Control Sample Parameterization Fitted from CS Signal (sum of B+→D0K+ and B+→D0p+) Double Bifurcated Gaussian BB background (excluding B+→D0K+) Crystal Ball Double Bifurcated Gaussian continuum background ARGUS Double Gaussian

Control Sample Parameterization B+→D0p+, D0 →K+p-p0 (only same sign events) mES Fisher mES, Fisher>0.5 mES, zoomed to signal region We got mES parameters from the fit

Control sample parameterization vs. MC Blue curve : CS fitted parameters Black points : MC events Important to use the signal parameterizations directly from data (CS)

Continuum Fisher parameterization Offresonance data os events ss events MC vs data

Toy MC expectations (RADS=1.4*10-2 ) Errors are asymmetrical! Pull mean =-0.02 Pull RMS = 1.004 Error expected 6.5*10-3 for generated value RADS=1.4*10-2 Example : With such an error we could get an rB as in the plot 

Toy MC expectations (RADS=0) Pull mean =-0.05 Pull RMS = 1.05 Error expected 5.2*10-3 for Generated value RADS=0 Errors are asymmetrical!

Fit validation on full MC sample (RADS=1.4*10-2 ) Same sign mES Fisher Opposite sign Fisher mES

Fit validation on full MC sample (RADS=1.4*10-2 ) mES, Fisher>0.5, opposite sign mES, Fisher>0.5, same sign

Fit validation on full MC sample (RADS=0.) Same sign mES Fisher Opposite sign Fisher mES

Fit validation on full MC sample (RADS=0.) mES, Fisher>0.5, opposite sign mES, Fisher>0.5, same sign

Results for MC cocktails Generated Cocktail with signal 1 no signal 1 with signal 2 no signal 2 Nsignal, total 2529 or 2492 2531±61 2480±60 2489±61 2460±61 RADS 14*10-3 or 0 (29±7)*10-3 (9±6)*10-3 (6±7)*10-3 (-9±5)*10-3 NBB, SS 467 440±61 440±60 384±60 NBB, OS 460 320±66 330±70 520±67 522±66 Ncont, OS 21229 21326±157 21320±157 21179±157 21178±156 Ncont, SS 7468 7520±98 7520±90 7561±99 7565±100 The fit is performed with signal mES parameterization from MC Inside 1s Inside 2s Inside 3s

Systematics error Source PDF error Peaking background BR errors 1*10-3 Peaking background BR errors Crossfeed ss<->os ratio 6*10-4 Efficiency ratio 2*10-4 Combined error 2*10-3 Estimation is done randomly varying the parameters (or yield) fixed in the fit. Estimation is done according to number of ss events passing os selection. Estimation is done by reweighing the Dalitz distribution of CA and DCS decays (crucial information is obtained from the estimation on B0->D0K*0 analysis. Statistical error > 5*10-3

R+/- vs. RADS We plan to quote R+, R- and RADS as final results and quote rB from R+ / R-

Future plans Unblind the fit. Publish the results. More details in: BAD 2173 physics note;