1 / 19

Constraints on α from B  Decays at BaBar

32 nd International Conference on High Energy Physics Beijing, China. Constraints on α from B  Decays at BaBar. Carlo Dallapiccola University of Massachusetts, Amherst For the BaBar Collaboration. Outline. Introduction and Motivation History of Measurements

Download Presentation

Constraints on α from B  Decays at BaBar

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. 32nd International Conference on High Energy Physics Beijing, China Constraints on α from B Decays at BaBar Carlo Dallapiccola University of Massachusetts, Amherst For the BaBar Collaboration C. Dallapiccola, ICHEP 2004

  2. Outline • Introduction and Motivation • History of Measurements • Time dependent CP Asymmetry in • Update of • Constraint on Unitarity Triangle angle a NEW! C. Dallapiccola, ICHEP 2004

  3. Measure Tree Motivation: Measuring a ACP(t) in decay to CP eigenstate: If dominates C. Dallapiccola, ICHEP 2004

  4. Penguin Motivation: Measuring a But...contribution from Interferes with Tree: ACP(t)  sin(2aeff) aeff = a+dapeng direct ACP ≠ 0 But can measure dapeng using isospin relations… C. Dallapiccola, ICHEP 2004

  5. Much smaller in rr system dapeng much smaller!! Motivation: Isospin and rr Gronau&London, PRL 65, 3381 (1990) Relative to experimentally simpler B  pp: 3 such relations (one for each polarization) C. Dallapiccola, ICHEP 2004

  6. Non-CP eigenstates CP eigenstate • * Observation of PRD 69, 031102 (2004) * • Run1-2 data (89M ) • Measure BF:  5 times larger than p+p- • Measure Polarization History: r+r-Observation But r is a vectorr+r-not a CP eigenstate? Transverse (h=±1) and longitudinal (h=0) helicity states It is almost a pure CP eigenstate (CP =+1) C. Dallapiccola, ICHEP 2004

  7. 89M History: r+r0and r0r0 • and measurements: • Update of in this talk * PRL 91, 171802 (2003)  hep-ex/0404029, submitted to PRL C. Dallapiccola, ICHEP 2004

  8. Fit params Set to 0 since fL1 ACP(t) in B0r+r- Decays • Reconstruct candidates  combine  • Find vertex positions of and otherB meson  • Tag flavor of • Compute Dt=tCP-ttag C. Dallapiccola, ICHEP 2004

  9. mESDE NN MV1,2 cos(qH)1,2Dt r helicities B kinematics Event shape r masses ACP(t) in B0r+r- Decays • Run1-3 data (122M ) • Max. Likelihood fit in 8 dimensional space • Fit for signal yield, polarization, Slongand Clong • Model: true signal, misreco. signal, continuum and 17 backgrounds 32133 events in fit sample: • 87% of background is continuum, 13% B backgrounds C. Dallapiccola, ICHEP 2004

  10. Fit: total mES DE Fit: bkgd Events with cleanest tags ACP(t) in B0r+r- Decays • Run1-3 data (122M )  Preliminary 314±34 Signal Events (205 tagged) fL=1.00±0.02 After cuts on likelihood ratio BaBar prelim BaBar prelim C. Dallapiccola, ICHEP 2004

  11. ACP ACP(t) in B0r+r- Decays • Run1-3 data (122M ) BaBar prelim • BaBar Run1-2 (89M ) Hep-ex/0404029, to PRL Dt (ps) C. Dallapiccola, ICHEP 2004

  12. Prelim studies show it’s not large ACP(t) in B0r+r- Decays: Run4 • Run1-4 data (226.6M )  Analysis in progress! • Add 86% more statistics • Comprehensive study of systematics due to interference of signal mode with other decays to p+p-p0p0 final states C. Dallapiccola, ICHEP 2004

  13. Search for B0r0r0 • Analysis description similar to that of B0r+r- • First result from Run1-2 (89M ) • Updated with Run1-4 data (226.6M ) • signal observed PRL 91, 171802 (2003) NEW! mES DE • Dominant Syst • a1p interfer: ±7.5 events • PDF variations: ±6 events • B bkgd: ±5.8 events BaBar prelim BaBar prelim C. Dallapiccola, ICHEP 2004

  14. Run1-2 result: Constraint on a • Preliminary update on a constraint: • BaBar BF(r+r-), BF(r0r0) and Slong and Clong • World average BF(r+r0)= (HFAG) prelim From r0r0 measurement a C. Dallapiccola, ICHEP 2004

  15. http://ckmfitter.in2p3.fr/ a from rr, rp, pp only • from full CKM fit (eK, Vub, Dmd,s, sin(2b)) Constraints on a Using BaBarrr, rp, and pp Measurements • Mirror solutions being disfavored! • From full CKM fit: C. Dallapiccola, ICHEP 2004

  16. Conclusion • First measurement of ACP(t) in B0r+r- decays • Updated (2004) with Run1-3 data (122M ) • Limit on • Updated with full Run1-4 sample (226.6M ) • Low BF allows for relatively clean measurement of a via isospin relations! • Important milestone for B-Factories! • Coming soon  update of ACP(t) in B0r+r- with full Run1-4 data sample and improved analysis C. Dallapiccola, ICHEP 2004

  17. Use Backup Slide • A00 small  Grossman-Quinn bound PRD 58, 017504 (1998). Gives same bound on dapeng C. Dallapiccola, ICHEP 2004

  18. Backup Slide • Distribution of r± helicity distributions for data • Clear demonstration of strong longitudinal polarization C. Dallapiccola, ICHEP 2004

  19. Backup Slide • Constraints in the r-h plane: C. Dallapiccola, ICHEP 2004

More Related