1 / 29

Title

Title. Searching for New Physics at the B factories: Measurements of sin2 b at BaBar. Gabriella Sciolla Massachusetts Institute of Technology Representing the BaBar Collaboration Beauty 2005 - Assisi, June 20-24, 2005. BaBar and PEP-II. BaBar detector 4 p collider detector

azia
Download Presentation

Title

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. Title Searching for New Physics at the B factories: Measurements of sin2b at BaBar Gabriella Sciolla Massachusetts Institute of Technology Representing the BaBar Collaboration Beauty 2005 - Assisi, June 20-24, 2005

  2. BaBar and PEP-II • BaBar detector • 4p collider detector • PEP-II asymmetricBfactory • 9.0 GeV e- beam • 3.1 GeV e+ beam • Peak luminosity • 9.1 x 1033cm-2s-1 • Integrated luminosity • Delivered: >268 fb-1 e+ e+ Most results in this talk are based on 227 M BB events Measurements of sin(2b) at BaBar

  3. (r,h) a b g (0,0) (1,0) The Beauty of the Unitarity Triangle Two ways of looking for New Physics: • Compare measurement of sides and angles • Measure angles in channels with different sensitivity to New Physics Measurements of sin(2b) at BaBar

  4. The three roads to b • Charmonium modes: • J/ψKS, ψ(2S)KS, χc1KS, ηcKS • J/ψKL • J/ψK*0 (K*0 → KS π0) • Open-charm modes: • D*+ D*−,D*+ D−, D+ D− • Penguin-dominated modes: • φK0, K+K−KS,KSKSKS • η′KS • KSπ0, ωKS,f0(980)KS Measurements of sin(2b) at BaBar

  5. mixing decay CP violation in interference between mixing and decays (hf) • When only one diagram contributes to the final state: • Example: B0 J/YKS: Measurements of sin(2b) at BaBar

  6. e+ Flavor tagging Q=(30.5  0.5)% Exclusive B reconstruction Dz~bgc Dt Precise Dt determination How to measure the CP asymmetry . e- B0 e- U(4S) m+ B0 p+ p- m- Measurements of sin(2b) at BaBar

  7. Phys. Rev. Lett. 94, 161803 (2005) The golden mode for sin2b:B0 charmonium K0 • Theoretically clean • Experimentally clean • Relatively large BF (~10-4) CP sample: mES[GeV] DE [MeV] Measurements of sin(2b) at BaBar

  8. Phys. Rev. Lett. 94, 161803 (2005) The golden mode for sin2b:CP fit in B charmonium K0 Unbinned maximum likelihood fit to Dt distribution CP=-1 CP=+1 sin(2b) = 0.722 ± 0.040stat ± 0.023syst Measurements of sin(2b) at BaBar

  9. SM test in B0  charmonium K0 cos(2β)<0 • Compare sides and angles • Both BaBar and Belle results used • Ambiguity resolved measuring sign(cos2b) in B0J/YK* • cos(2b)=-0.68 excluded at 86.6%CL[PRD 71 (2005)032005] • Excellent agreement with constraints from the sides • Another SM triumph? . cos(2β)>0 SM test #2: Compare b in various channels Measurements of sin(2b) at BaBar Measurements of angles NOT included in fit

  10. The bccd trees:B0 open charm • Tree measures sin2b from bccd transitions • Penguin expected to be small in SM (< few %) • D*D*: as large as Db = 0.6 [Grossman and Worah, 1997] u,c,t New Physics could have large effects Measurements of sin(2b) at BaBar

  11. New The open charm trees: Recent update: B0 D*+D*- BaBar Preliminary • Vector-vector final state: • CP-even and CP-odd admixture • Transversity analysis measures fCP-even CCP+ = +0.06 ± 0.17 ± 0.03 -SCP+ = 0.75 ± 0.25 ± 0.03 fCP+ = (87.54.4 0.7)% In good agreement with SM Measurements of sin(2b) at BaBar

  12. hep-ex/0505092 The open charm trees:B0 D(*)D Updated Updated New Measurements of sin(2b) at BaBar

  13. The key to New Physics: The Penguin Modes Decays dominated by gluonic penguin diagrams • The typical example: B0fKS • No tree level contributions • In SM, top quark dominates the loop: C~0; S~sin2b • Impact of New Physics could be significant • New particles could participate in the loop  new CPV phases • Low branching fractions • Measure ACP in as many bsqq penguins as possible! • φ K0, K+ K− KS,η′ KS, KS π0, KS KS KS, ω KS,f0(980) KS NP SM Measurements of sin(2b) at BaBar

  14. Phys. Rev. D 71, 091102(R) (2005) The golden penguin: B0fK0 Combined fKS and fKL fit: Measurements of sin(2b) at BaBar

  15. Phys. Rev. D 71, 091102(R) (2005) Related channel: B0 K+K-KS • For non resonant B0K+K-KS decays, hCP = 2 feven- 1 • feven measured from angular moment analysis of the K+K- system Measurements of sin(2b) at BaBar

  16. hep-ex/0502013 (accepted by PRL) A new golden penguin: B0KSKSKS • Theoretically clean • Penguin dominated CP=+1 eigenstate • Experimentally challenging • B decay vertex uses KS pseudo-particles and beam spot constraint Measurements of sin(2b) at BaBar

  17. Phys. Rev. Lett. 94, 191802 (2005) The silver penguin: B0h’KS • Relative large BF ~ 6 x 10-5 • Theoretically less clean than fKS • Tree diagram possible … but Cabibbo and color suppressed… • |DS| =|SYK-SPenguin|~ 0.01QCDFact 0.1SU(3) Sη′Ks = 0.30± 0.14±0.02 Cη′Ks = −0.21±0.10±0.02 Measurements of sin(2b) at BaBar

  18. hep-ex/0503011 hep-ex/0408095 hep-ex/0503018 The challenging penguins: B0p0KS, f0KS,wKS • B0p0KS: • dominated by • tree contribution are non negligible (DS ~ 0.1 – 0.2) • Experimental challenge: BCP decay vertex reconstruction (sDt~1ps) • B0f0KS: • In SM dominated by • B0wKS: • In SM dominated by • But tree can be relatively large Measurements of sin(2b) at BaBar

  19. “sin2b” in penguins: BaBar only • Although each • measurement is • compatible with J/YKS, • a trend is visible • h’KS has the most • significant shift • (~2.9 s if theory • uncertainties neglected) • … but statistical errors are • still large… Measurements of sin(2b) at BaBar

  20. Statistical fluctuation or first signs of New Physics? • Average of BaBar • and Belle results • Boxes are SM expected • ranges for -hfSf from • Beneke, hep-ph/0505075 • Shift still significant… SJ/Y- Spenguins > 3 s “sin2b” in penguins: BaBar + Belle Measurements of sin(2b) at BaBar

  21. Precision measurements of sin2b in many different channels are a powerful probe for New Physics • B0 charmonium K0: our calibration point (ssin2b ~ 0.04) • B0 open charm: no smoking guns so far • B0 penguin modes: intriguing shifts observed • New Physics or statistical fluctuations? • Time and data will tell… • Goals for BaBar luminosity • Summer 2006: 500 fb-1 • Summer 2008: 1 ab-1 Summary and Conclusion Measurements of sin(2b) at BaBar

  22. Backup slides -------------------------------------------------------------------- Measurements of sin(2b) at BaBar

  23. Transversity analysis • D*+D*- is not a CP eigenstate • sum of L=0, 2 (CP even) and L=1 (CP odd) • CP odd fraction Rdetermined by transversity analysis Measurements of sin(2b) at BaBar

  24. D*D analysis SM expectations • D+D- • D*D Measurements of sin(2b) at BaBar

  25. cos and sin fits in penguin modes Measurements of sin(2b) at BaBar

  26. hep-ex/0503011 The challenging penguins: B0p0 KS • In SM these decays are dominated by • tree contribution are non negligible • DS ~ 0.1 in model dependent QCD calculations • DS ~ 0.2 in SU(3) • Experimentally challenging • BCP decay vtx from KS and beam spot • KS tracks with > 3 SVT: sDt~1ps • Unbinned max likelihood fit: Nsig = 300 ± 23 Measurements of sin(2b) at BaBar

  27. hep-ex/0408095 hep-ex/0503018 Two more penguins:B0 f0KS and B0 wKS B0 f0KSdominated by b sss B0 ωKS : dominated by b → sdd Tree contamination can be relatively large Measurements of sin(2b) at BaBar

  28. Results presented at Moriond 2005 The Other Trees: Recent update: B  D*+D*- BaBar Preliminary • Vector-vector final state: • CP-even and CP-odd admixture • Transversity analysis measures fodd • fodd = (12.54.4 0.7)% CCP+ = +0.04 ± 0.14 ± 0.02 -SCP+ = 0.65 ± 0.26 +0.09-0.07 ± 0.04  Good agreement with SM Measurements of sin(2b) at BaBar

  29. Penguins vs tree Measurements of sin(2b) at BaBar

More Related