1 / 21

Measurements of g and sin(2 b+g ) in BaBar

Measurements of g and sin(2 b+g ) in BaBar. Gianluca Cavoto Princeton University Universit à di Roma ‘La Sapienza’ On behalf of the BaBar Collaboration ICHEP'04 32 nd International Conference on High Energy Physics. Angle g of the Unitarity Triangle.

bessie
Download Presentation

Measurements of g and sin(2 b+g ) in 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. Measurements of g and sin(2b+g ) in BaBar Gianluca Cavoto Princeton University Università di Roma ‘La Sapienza’ On behalf of the BaBar Collaboration ICHEP'04 32nd International Conference on High Energy Physics Gianluca Cavoto

  2. Angle g of the Unitarity Triangle Measure relative phase between Vub and Vcb • Process mediated by both b  c and b u amplitudes • Results (all preliminary) g from direct CP asymmetry sin(2b+g) time dependent CP asymmetry Updated and newresults Gianluca Cavoto

  3. Interference when D final state common to both D0and D0 g from direct CP violation Relative size (rB) of B decay amplitudes Not well constrained by theory. Larger rB, larger interference, betterg experimental precision BaBar hep-ex/0402024 Belle hep-ex/0406067 Relative strong phase (dB) unknown Different incarnations… Gianluca Cavoto

  4. Theoretically clean, but with 8-fold ambiguity Gronau London Wyler method D decays into CP eigenstate • CP modes:small D0branching ratio Select CP-even and CP-odd final states 3 observables, 3 unknowns • Normalize to D0decay into flavour state (K-p+) Experimentally Gianluca Cavoto

  5. High reconstruction efficiency Analysis techniques Cerenkov angle • No charge confusion. • Clear separationDp/DK Reject events topological variables in Neural Network or Fisher discriminant data MC BF(B  DK) ~ 10 -4, BF(D f) ~ 10 -2reconstruct as many f final states as possible Gianluca Cavoto

  6. B- CP+ B+ CP- B- CP- B+ CP+ Combine several final states B-D0CPK(*)- yields CP+ (p+p-,K+K-) NBB=214 106 D0CP K - CP- (KSp0) D0p background D0CP K* - (K* - KSp -) Adding KSf, KSw NBB=227 106 Gianluca Cavoto

  7. From DCPK* Loose bound on rB GLW B-D(*)0CPK(*)- results D0CP K - D0CP K* - (K*- KSp -) NBB=227 106 NBB=214 106 Additional systematic error on ACP- ( CP even background) D*0 (D0CPp0)K - NBB=123 106 More CP eigenstate final states still to be added… More statistics needed to constrain g Gianluca Cavoto

  8. Atwood Dunietz Soni method D decay into flavor state dB dD Count B candidates with opposite sign kaons Input: Phys.Rev.Lett.91:171801,2003 D decay strong phase dDunknown Gianluca Cavoto

  9. ADS results D*0(D0g)K D0K D*0(D0p0)K NBB=227 106 No signal in current dataset Gianluca Cavoto

  10. Sensitive to rB (RADS~r2B) rB from ADS method D*0(D0p0)K D*0(D0g)K D0K RADS R*ADS No AADS measurement Not easy to determine g Gianluca Cavoto

  11. If we knew the charm phase shift dD? B-D(*)0K- D0(KSpp) Dalitz analysis Amplitude for B-/B+ “D0”K-/K+ g=75,d=180,rB=0.125 Sensitivity to g Isobar model for f(m2+ ,m2- ) can fix phase variationdD across Dalitz plot. Only two-fold ambiguity in g extraction r(770) DCS K*(892) Gianluca Cavoto

  12. Determined on D* D0p sample D0(KSp+p-) Dalitz model CA K*(892) Plot of mpipi r(770) DCS K*(892) No D-mixing, No CP violation in D decays Gianluca Cavoto

  13. 40 8 83 11 B+ B+ B- B- NBB=211 106 B-D0K-, B-D*0K- DCS K*(892) 261 19 D0K D*0(D0p0)K DCS K*(892) D*0(D0g)K Dalitz projection for mES >5.272 GeV/c2 Signal plus background PDF superimposed Gianluca Cavoto

  14. g from B-D(*)0[KSp+p-]K- With current statistics, no rB sensitivity for rB<0.10 180 A posteriori rB(rB*) with uniform a priori g D0K- 0 -180 rB D0K- D*0K- 0.3 180 68% g D*0K- 0 95% 0. 0. 0.3 0.3 -180 r*B 0.3 Bayesian confidence regions Dalitz model syst Gianluca Cavoto

  15. GLW ADS Critical rB… g sensitivity projection for 500 fb-1 D0 Dalitz rB =0.1 s(g) rB =0.2 GLW only ADS only (dD and dB unknown) GLW+ADS rB =0.3 g = 62o rB g measurement from combination of many modes (multiple constraints on rB) g 0 90 180 From ADS Gianluca Cavoto

  16. The final state is accessible from both B0 and B0 Time dependent CP analysis sin(2b+g) with B0D(*)-p+/r+ ~l2 ~l4 favored bc amplitude suppressed bu amplitude time-dependent CP violation arises from interference of mixing and decay: Asymmetry parameters Lepton tag Exclusive reconstruction of D-p+, D*-p+,D-r+ D*r Combinatoric BB Peaking BB Continuum Partial reconstruction of D*-p+ Gianluca Cavoto

  17. NBB=124 106 B0 D(*)0K(*)0 Sensitivity given by Search for b  u transition (self tagging mode) Eventually TD analysis… No signal… Gianluca Cavoto

  18. Unitarity triangle constraints Confidence regions in r-hplane http://www.utfit.org hep-ph/0408079 . Combination of BaBar a and c results with uniform prior in r 68% C.L. 95% C.L. Improve bound using SU(3) r from Search for B0 Dsr B0D+sp - NBB=90 106 Not encouraging for Dr… Phys.Rev.Lett.90:181803,2003 Gianluca Cavoto

  19. Conclusion • More modes and techniques added to measureg • GLW, ADS, D0K Dalitz, time-dep. sin(2b+g) • No single golden technique • Constraints on b u amplitude in B DK • Evidence for small rB • Sensitivity to g relies heavily on rB • g from combination of many modes Combination of BaBar GLW+ADS+D0K Dalitz 68 %C.L. 95 % C.L. Gianluca Cavoto

  20. Backup slides Gianluca Cavoto

  21. sin(2b+g): results NBB=110 106 Exclusive reconstruction of D-p+, D*-p+,D-r+ - higher signal purity, lower efficiency Higher pp resonance Included in syst.error Partial reconstruction of D*-p+ - highefficiency, more background NBB=178 106 Gianluca Cavoto

More Related