Charmless Quasi-two-Body Modes at BaBar Fernando Palombo Dipartimento di Fisica and INFN, Milan for The BaBar Collaboration ICHEP’04 August 16 – 22 , 2004 Beijing, China 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 Outline Motivation Analysis Technique : Overview B0 →   B+ →  +, B+ →  + B0 →  B0 → a1(1260) - B0 →ρ0 KS B0 → KS KS KS Conclusion + 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 Motivation We look to processes dominated by penguin loops or CKM-suppressed decay (Rare Decays) An optimal place for measurements sensitive to new physics ( new contributions to the penguin amplitude beyond the SM) Check of QCD Factorization, Perturbative QCD, Flavour SU(3) 18/08/04 Fernando Palombo , ICHEP 2004

Analysis Technique : Overview Unbinned Maximum Likelihood (ML) Fit Kinematic and event shape variables Apply loose cuts to keep side-bands for background fitting Main background : e+e- → q q continuum (q = u,d,s,c) fit accounts also for B B background Extract from ML fits: yields, charge asymmetries, efficiencies, PDF parameters Several Crosschecks “Toy MC” experiments, control samples Analyses presented in this talk done in Q2B approximation 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 Expected dominated by b → s loop amplitudes K+ K, *+,  sK* enhanced + K K*+ * suppressed (Lipkin,199) Interference Ali et al., PRD59, 014005 (1999), M. Z. Yang et al., NPB609,469 (2001) M. Beneke et al., NP B651,225(2003), H.K. Fu et al., PRD69,074002 (2004) Chiang et al., PRD69,934001 (2004) ICHEP/11-0936 BaBar-Conf-04/023 18/08/04 Fernando Palombo , ICHEP 2004

New Measurement of B0 → New measurement with 182 106 BB pairs . ηK0 Now observed by BaBar PRL 92, 061801 (2004) Predicted large charge asymmetry Chiang et al., PRD69,034001(2004) 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 B+→ + and B+→ + Expected dominated by a CKM-suppressed tree diagram Vub ICHEP /11-0936 BaBar-Conf-04/023 18/08/04 Fernando Palombo , ICHEP 2004

New Measurements of B+→ + and B+→ + _ _ 182 106 BB pairs used in this analysis + + 18/08/04 Fernando Palombo , ICHEP 2004

New Measurement of B0 → Subm. to PRL _ Measurements done with 89 106 BB pairs _ Remeasurement done with 182 106 BB pairs As expected we improve upper limits. Very interesting for calculation of upper bound on ΔS in B0 decay modes dominated by penguins 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 Isoscalars ULs and ΔS With new ULs in B decays to isoscalar pairs measured by BaBar great improvement in the bounds of ΔS = S – sin 2 β S is the coefficient of sin term in time evolution of the system sin 2 β is S measured in B0 decays to charmonium K0 Previous bound New bounds Gronau, Rosner,Zupan hep-ph/0403287 2003 BaBar + Belle average η'K0 BaBar new measurement in η'K0 : S=0.27 ±0.14 ±0.03 ( see Hoecker C=-0.21± 0.10 ±0.03 talk, this conf ) see also :Grossman et al. PRD68 ,015004 (2003) 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 B0→ a1+- (a1→++-) Rare decay with a BF not yet measured. These decays can be used to study CP asymmetry for an independent measurement of sin 2α But first we have to measure the BF to see if there is any signal. Analysis done with a statistics of 124 106 BB pairs. Simple analysis done in Quasi-2-Body approximation. Dalitz plot analysis is in progress _ ICHEP/11-0969 BaBar-Conf-04/002 18/08/04 Fernando Palombo , ICHEP 2004

Measurement B0→ a1- ( a1→++- ) Yield 472 ±46 Br(B0→a1+ -) = (42.6 ± 4.2stat ± 4.1syst ) 10-6 3  m = 1.19 ± 0.02 GeV/c2 Γ = 312 ± 55 MeV/c2 a1 a1 Observation of this decay stat. sign. > 10 σ 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 B0→ρ0K0S Penguin dominated mode : Another candidate for measuring CP-violating asymmetries (sin 2 β ) in penguin-dominated modes Analysis done using 227 106 BB pairs Several classes of Charmless and Charm backgrounds described by PDFs in ML fit ICHEP/11/0992 BaBar-Conf-04/046 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 B0→ρ0K0S Yield : 99 ± 19 Br(B0→ρ0KS ) = (5.1 ± 1.0 ± 1.2) 10-6 Evidence of this mode at 3.5 σ (ρ0KS + σ KS ) signal at 6.1 σ 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 B →KS KS KS Penguin dominated mode : This decay is not Cabibbo-suppressed Already measured by Belle with 78 fb-1 Br(B0→KS KS KS ) = (4.2 ± 0.8) 10-6 This measurement done with 211 106 BB pairs +1.6 -1.3 _ 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 B0→K0S K0S K0S Yield 71 ± 9 ε = 5.2 % syst. err = 13 % Br(B0→ KS KS KS ) = (6.5 ± 0.8 ± 0.8) 10-6 Significance > 10 σ ICHEP/11-0929 BaBa-Conf-04/032 18/08/04 Fernando Palombo , ICHEP 2004

Fernando Palombo , ICHEP 2004 Conclusion Observations of B0 → ηK0 , ηρ+, η'+ , a1+ - Evidence for B0 → ρ0 at 3.5 σ B0 → 3 seen with stat. sign. > 10 σ No evidence in these decay modes for direct CPV Severe tests of factorizion models (predictions of BF, charge asymmetry, etc) KS KS all new results are preliminary 18/08/04 Fernando Palombo , ICHEP 2004