1 / 15

Direct CP Violation and Charmless Branching Fractions with B A B AR

Direct CP Violation and Charmless Branching Fractions with B A B AR. Jinwei Wu University of Wisconsin On Behalf of B A B AR Collaboration. ICHEP 2004, Aug 16 th – 22 nd , 2004 Beijing, China. Motivation Analysis procedure Results Summary and outlook. Introduction.

sileas
Download Presentation

Direct CP Violation and Charmless Branching Fractions with B A B AR

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Direct CP Violation and Charmless Branching Fractions with BABAR Jinwei Wu University of Wisconsin On Behalf of BABAR Collaboration ICHEP 2004, Aug 16th – 22nd, 2004 Beijing, China • Motivation • Analysis procedure • Results • Summary and outlook

  2. Introduction • CP violation has been observed in Kaon system • Measurement of sin(2) with (cc)K0 established CP violation in B0 meson system arising from interference between mixing and decay amplitude • We have not yet observed direct CP violation in B meson system arising from decay amplitude It took more than 30 years to establish DCPV in Kaon system! PRL 83, 22 (1999) • Sources of direct CP asymmetries: Interference between two decay amplitudes (Ai) with different strong (i) and weak phases (i)

  3. Searching for Direct CPV in charmless B decay • Competing amplitudes with different weak phases make large asymmetries possible • Loop diagrams from New Physics (e.g. SUSY) can modify SM asymmetries/branching fractions • Experimentally – look for charge asymmetries: • Experimental challenge • Small branching fraction and large background from continuum (u, d, s, c) production • Charge bias • Detector: trigger, tracking, reconstruction • Event selection, particle ID, analysis • Asymmetries in background

  4. Analysis Procedure signal B background Event selection: E(GeV) • Quality cuts for tracks and showers • Continuum rejection using event shape variables • Kinematic signal identification with mES and E: mES (GeV/c2) Maximum Likelihood Fit to determine yields and asymmetries simultaneously: BABAR • B mass • B energy • Event shape • Particle ID K separation() K separation Separate signal from light quark background Separate Kaon from Pion pLAB (GeV/c)

  5. Searching for Direct CPV in B0K+ s s K+ K+ B0 p- B0 p- 227x106B pairs • Motivation • Both tree(T) and penguin(P) diagram contribute: Tree • Clean charmless mode with large BF: HFAG, March 2004 • Method • Extended ML fit simultaneously determines: • n, nK, nKK, AK and AKb • and uses: • c PDFs separately for {K+ ,K, +, } from PID control sample Penguin

  6. First Observation of Direct CPV in B decay B0K+ BABAR 4.2, syst. included BABAR B0K+ background subtracted signal enhanced

  7. AK : Systematics and Cross Checks Systematics: • CPV due to mixing ruled out • Asymmetries consistent in different Kaon momentum ranges • Asymmetries consistent when including decay time information • Asymmetries consistent in different running period • Asymmetries consistent with SM predictions PRL 89, 281802 (2002) Background charge asymmetry free in the fit: Running period:

  8. B+  K++, ++ 182x106B pairs • Motivation • measure  using a full Dalitz plot • look for direct CPV PRL 86, 2720 (2001) B+ K++ • Method • full Dalitz plot analysis • combined fit for B+ and B • Veto charm, charmonium decays: J/, (2S), D0 • Use relativistic Breit-Wigner lineshapes for resonances unless stated otherwise 148267 signal events B+ ++ 38351 signal events • Syst. dominated by: • bkg Dalitz plot characterization • efficiency uncertainty on the DP

  9. B+  K++ 182x106B pairs BABAR preliminary BABAR preliminary m(K+) (GeV/c2) m(+) (GeV/c2) LASS param.

  10. B+  ++ 182x106B pairs BABAR preliminary BABAR preliminary m(+) (GeV/c2) m(++) (GeV/c2) Flatte lineshape No evidence of: ‘’, c0 and f0(1370)

  11. B0  K+0 454 ± 24 B0  D00 213x106B pairs • Method • full Dalitz plot analysis • separate fit for B0 and B0 • 4-D convolution treatment for misreconstructed signal events • fit B0  D00 as cross check • Motivation • extract intermediate resonances • constrain penguins in Bρ • constrain  of the UT • look for direct CPV 1230 ± 74 signal events BABAR preliminary

  12. B0  K+0 213x106B pairs K s-wave LASS param. K*(892)00 4.2, syst. included Syst. dominated by ignoring ‘minor’ intermediate states

  13. Summary and outlook • For other results, eg B0, B0, see talk by Markus • First observation (4.2) of direct CP violation in B decay amplitude hep-ex/0407057 Submitted to PRL • Other results are preliminary • Charmless three body B decays move the era of Dalitz plot analysis. Many branching fractions and ACP measured, with new observations of: B+f2(1270)+, B0K*(892)00 • ACP precision achieved 3~25%, watch for future updates

  14. Backup slides

  15. B0  K++ background subtracted B+c0K+ B+f0(980)K+ B+ρK+ B+K*(892)+ B+K*(1340)+

More Related