1 / 19

Study of CP Violation in B 0   +  –  0 / K S Decays

Study of CP Violation in B 0   +  –  0 / K S Decays. Jinwei Wu Harvard University. Aug 21 st , 2006. CP violation Extraction of α from B  ρ  decay Extraction of β from B  K S  decay Conclusion. Direct CP Asymmetry. . . . . no CPV.

karleigh-walls
Download Presentation

Study of CP Violation in B 0   +  –  0 / K S Decays

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. Study of CP Violation in B0+–0/KS Decays Jinwei Wu Harvard University Aug 21st, 2006 • CP violation • Extraction of α from B  ρ decay • Extraction of β from B  KS decay • Conclusion

  2. Direct CP Asymmetry     no CPV • Sources of direct CP asymmetries: Interference between two decay amplitudes (Ai) with different strong (i) and weak phases (i) CPV

  3. Time-dependent CP Asymmetry B0 fCP no oscillation oscillation B0 B0 fCP no oscillation B0 oscillation

  4. Mixing induced CPV in Charmless B Decay • Decay-amplitude weak-phase structure for b → uud : • Time dependent asymmetry probes eff:

  5. Quasi-two-body Analysis R. Aleksanet al, 1990 free Penguin scenario • Quasi-two-body approximation, ignore interference effect • 6 observables through a time-dependent fit: Measure CP violation, but not necessarily phase 

  6. A3 = f+A+ + fA+ + f0A00 A3 = f+A+ + fA+ + f0A00 00 +– + Snyder-Quinn Method Quinn, Snyder PRD 48, 2139, (1993) Idea: Extract  and the strong phases using the interference between B0  +0 amplitudes +0amplitude parameterization: m(0)2 (GeV2) • The f+, ,0 are relativistic Breit-Wigner form factors m(+0)2 (GeV2)

  7. The Square Dalitz Plot Toy MC det|J|

  8. Fit Projection Plots Strong signal with 347M BBbar ρ(770) dominate

  9. Extract physics parameters • Time-dependent Dalitz plot approach should supersede the previous quasi-two-body analysis, with interference among resonances taken into account. hep-ex/0608002 * Using a Q2B approach and 144fb-1 data, BELLE measured:

  10. ρ  =? B0 + ρ+ B0 ρ+ + =? B0  ρ B0 Probing Direct CP Violation Define physically more intuitive quantities: 3.0 Large Direct CPV not expected…

  11. Road to  Dalitz plot specific measurements: • What is the strong phase between B0ρ+ and B0ρ+? • What is ?

  12. Measuring sin2β with Charmless B decay decays are tree and penguin diagrams, with equal dominant weak phases decays are pure “internal” and “flavor-singlet” penguin diagrams High virtual mass scales involved: believed to be sensitive to New Physics Both decays dominated by single weak phase BR~ 10-3 B0J/yK0 Tree: sin2b=0.69±0.03 B0fK0 Penguin: BR~ 10-5 New Physics? 3 ?

  13. Sources of Standard Model Pollution There are many modes that dominantly decay via bs(qq)…but not all modes were created equal There are various estimates for the deviation from sin2β due to SM pollution…most of them expect a larger value! This is ok; still gives sin2b in SM. c,t b s K0 B0 d d d w,p0,r0,h’(?),f0(?)… d b u w,p0,r0,h’(?),f0(?)… B0 u s CKM and color suppressed.. but will lead to slight deviation. K0 d d

  14. sin2β from B0KS Final State • quite a few CP events in this decay including r0KS and f0KS • also a higher (f?) resonance ~1500 MeV • there is a possible tree diagram which contaminates the sin2b measurement • time-dependent CP has been measured for f0Ks and r0Ks Last summer, Belle presented a (time and tag independent) Dalitz Plot analysis of this mode…this approach will be important in the future!

  15. B0KS Final State • A Dalitz plot with rich structures, apart from CP eigenstates, there are also flavor eigenstates. • K*(890)π, K*0(1430)π are important for testing QCD factorization and other schemes. • Can look for direct CP violation and test SU(3) symmetry in the B→ PV decays • Interference with flavor eigenstates can help lift the degeneracy in the sin2β measurement K*(890) K*(1430)

  16. B0f0KS ML fit : • Systematic errors dominated by • Fit bias & interference with other modes

  17. B0ρ0 KS • Complications • high level of bkg • ρ is broad • Interference with ππ s-wave at both high mass and low mass BaBar: S=0.17±0.52±0.26 C=0.64±0.41±0.25

  18. Analysis of B0KS Dalitz Plot Similar analysis technique, need to handle additional flavor eigenstates f0 r0 f??? Strong signal with 347M BBbar

  19. Conclusion • Extraction of α from B ρπ • The isospin analysis appears hopeless for the near future • There is hope for the Dalitz plot analysis although it’s technically difficult. • Extract α with no ambiguities. Especially useful when combined with other experiments or other measurements of α. • Latest result in hep-ex/0608002 • Pioneered time-dependent Dalitz plot analysis for B decays. Framework setup to study other three-body B decays. • Already tested on B0→K+–0 • Close to finish CP measurement of B0→K0+–,where CP violation in s-penguin decay and direct CP violation will be tested • Foresee preliminary results in September.

More Related