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

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 new results Gianluca Cavoto

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

Gronau London Wyler method Theoretically clean, but with 8-fold ambiguity Gronau London Wyler method D decays into CP eigenstate Select CP-even and CP-odd final states 3 observables, 3 unknowns Normalize to D0 decay into flavour state (K-p+) Experimentally CP modes: small D0 branching ratio Gianluca Cavoto

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

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

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

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 dD unknown Gianluca Cavoto

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

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

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

D0(KSp+p-) Dalitz model 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

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

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- -180 rB 0.3 D0K- D*0K- 180 68% g D*0K- 95% 0. 0.3 0. 0.3 -180 r*B 0.3 Bayesian confidence regions Dalitz model syst Gianluca Cavoto

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

sin(2b+g) with B0 D(*)-p+/r+ Time dependent CP analysis sin(2b+g) with B0 D(*)-p+/r+ The final state is accessible from both B0 and B0 ~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

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

Unitarity triangle constraints Confidence regions in r-h plane 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 - overlay the best fit for UT NBB=90 106 Not encouraging for Dr… Phys.Rev.Lett.90:181803,2003 Gianluca Cavoto

Conclusion More modes and techniques added to measure g 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 Add rb again Combination of BaBar GLW+ADS+D0K Dalitz 68 %C.L. 95 % C.L. Gianluca Cavoto

Backup slides Gianluca Cavoto

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+ - high efficiency, more background NBB=178 106 Gianluca Cavoto