1 / 24

LHCb-Babar Meeting 8 April 2005.

A first look at B s → J/ YF in LHCb. Paul Soler University of Glasgow and Rutherford Appleton Laboratory. LHCb-Babar Meeting 8 April 2005. Contents. Motivation Physics aims Angle c from B s → J/ Yf LHCb Experiment Analysis of B s → J/ Yf Toy Monte Carlo Sensitivity New Physics

quinn-terrell
Télécharger la présentation

LHCb-Babar Meeting 8 April 2005.

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. A first look at Bs→J/YF in LHCb Paul Soler University of Glasgow and Rutherford Appleton Laboratory LHCb-Babar Meeting 8 April 2005.

  2. Contents • Motivation • Physics aims • Angle c from Bs→J/Yf • LHCb Experiment • Analysis of Bs→J/Yf • Toy Monte Carlo • Sensitivity • New Physics • Conclusions Work carried out in collaboration with: Stuart Paterson (Glasgow) Andrew Pickford (Glasgow) Borrowed from: G. Raven’s analysis in 2003 LHCb-Babar Meeting, 4 April 2005

  3. Motivation • Bs → J/Yf is the “gold plated” decay mode in the Bs system, similar to theBd → J/YKs in the Bd system • This mode is theoretically clean (very small penguin contributions). • It provides a measurement of the unitarity angle cdg, which is predicted to be very small (~0.02) in the SM. • Sensitive to new physics • Exploits the production capabilities of Bs mesons at the LHC (not available at B-factories) • Exploits UK investment in the RICH and VELO detectors LHCb-Babar Meeting, 4 April 2005

  4. Physics aims • CKM matrix: CKM matrix provides link between mass eigenstates and weak eigenstates Experimentally: LHCb-Babar Meeting, 4 April 2005

  5. Physics aims CKM matrix in Wolfenstein parametrization ~O(l5): _ b: Bd-Bd Mixing Phase g: Weak Decay Phase _ cdg : Bs-Bs Mixing Phase (From CKM-fit hep-ph/0406184) Standard Model: a=p-b-g LHCb-Babar Meeting, 4 April 2005

  6. (db) (ut) Im Im  a a      c Re 1 Re  c c Physics aims • Two main unitarity triangles: LHCb-Babar Meeting, 4 April 2005

  7. Physics aims • Channels to be used to extract unitarity triangles: LHCb-Babar Meeting, 4 April 2005

  8. c from Bs→J/Yf (Diagrams) Decay Mixing (This l is not Wolfenstein parameter!) LHCb-Babar Meeting, 4 April 2005

  9. c from Bs→J/Yf (Asymmetry) • Asymmetry: (if J/YF is eigenstate) • But J/Y F is not pure CP eigenstate: CP even CP odd CP even LHCb-Babar Meeting, 4 April 2005

  10. c from Bs→ J/Yf (Non-CP) • Change due to mixed eigenstate: The effect of the CP admixture is to dilute extraction of c and to add a small coefficient in front of cos(Dms) since: LHCb-Babar Meeting, 4 April 2005

  11. c from Bs→ J/Yf (Transversity) • Extraction of CP eigenstates (transversity analysis): Three polarization states • Bs→J/Y(l+l-)F(K+K-) has three angles but can be put into J/Y reference frame with only one angle (the transversity qtrq) that comes out of F(K+K-) decay plane . J/Y rest frame LHCb-Babar Meeting, 4 April 2005

  12. c from Bs → J/Yf (Transversity) • Angular distribution in transversity: • Once CP eigenstates established, the analysis proceeds in the same manner to establish CP asymmetries. • References: • Durham workshop CERN-TH/2001-034 (hep-ph/0102159) • LHCb notes: LHCb 98-067 & G. Raven, LHCb 2003-118 and LHCb 2003-119 • “B decays at the LHC”: CERN-TH/2000-101 LHCb-Babar Meeting, 4 April 2005

  13. LHCb Experiment • LHCb Detector: forward single arm spectrometer at LHC • Acceptance: 10-300 mrad bending 10-250 mrad non-bending LHCb-Babar Meeting, 4 April 2005

  14. LHCb Experiment • Exploit VELO for Bs proper time measurement (Bs oscillations) • Proper time resolution: ~40 fs • Dms sensitivity: 68 ps-1(Standard Model ~ 20 ps-1) • Exploit RICH for particle identification: F(K+K-) • PID: p-K separation 1-100 GeV RICH1 LHCb-Babar Meeting, 4 April 2005 RICH2

  15. Select J/ψ Calculate Transversity Combine to select Bs Real MC Data SelectФ Write Histos & NTuples Bs → J/Yf (Da Vinci Analysis) • Work flow of Bs → J/Yfanalysis using Da Vinci (LHCb analysis package) • First ever LHCb analysis run on the Grid (GLite) by S Paterson LHCb-Babar Meeting, 4 April 2005

  16. Bs → J/Yf (Da Vinci Analysis) • Ran with 100,000 Bs → J/Yfsignal events Efficiency F(K+K-): 9.8% Energy resolution: 9 MeV Efficiency J/Y(m+m-):14.4% Energy resolution: 13 MeV LHCb-Babar Meeting, 4 April 2005

  17. Bs → J/Yf (Da Vinci Analysis) • Transversity distribution looks promising • Contributions from CP odd (ℓ=1) & CP even (ℓ=0,2) states • Bs Efficiency ~ 8.2% • Energy resolution: 17 MeV • Event selection quite clean LHCb-Babar Meeting, 4 April 2005

  18. Bs → J/Yf (Da Vinci Analysis) • LHCb 2003-119 by Gerhard Raven, used a toy MC for re-optimization TDR (20% CP odd; 80% CP even) Very similar to distribution extracted. Need to fit to CP-odd versus CP-even LHCb-Babar Meeting, 4 April 2005

  19. Bs → J/Yf (G. Raven toy MC) • Proper time resolution: 38 fs (G Raven LHCb 2003-118) • Annual yield: Assume Lint=2 fb-1(107 s at 2x1032 cm-2s-1); sbb=500mb; fB=10% for Bs hadronization; BRvis=3.1x10-5 • Implies: 113 k events per year (with 8.2% efficiency) LHCb-Babar Meeting, 4 April 2005

  20. Bs → J/Yf (G. Raven toy MC) • G. Raven’s toy Monte Carlo varied a number of parameters to extract sensitivities _ q=+1(-1) for events tagged as Bs (Bs) w=wrong tag fraction (=0.5 for untagged) Assumed Q=etag(1-2w)2=4.5% (w=35%, etag =50%). Untagged sample can be used to extract lifetime difference: • One can fit for 5 parameters: LHCb-Babar Meeting, 4 April 2005

  21. Bs → J/Yf (G. Raven toy MC) • Results: LHCb-Babar Meeting, 4 April 2005

  22. Sensitivity Bs→ J/Yf • In one year expect ~ 113 k events (negligible background) • s(sin 2c) ~ 0.064 (depending on ) • In five years:s(sin 2c) ~ 0.03 (Standard Model:sin 2c ~ 0.04) One year LHCb-Babar Meeting, 4 April 2005

  23. New Physics • Left-Right symmetric models (eg. SB-LR) LHCb-Babar Meeting, 4 April 2005

  24. Conclusions • Bs→J/Yf is a very promising channel to study at LHCb • Not accessible at B factories or Tevatron • Standard Model prediction for cis very small (~ 0.02) • New Physics could make c significantly larger than SM • Started analysis of Bs→J/Yf and can achieve yields of ~100k events per year • Using Toy Monte Carlo (G Raven), LHCb can probe c to values very close to SM predictions, s(sin 2c) ~ 0.064 within 1 year. LHCb-Babar Meeting, 4 April 2005

More Related