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Rare hadronic B decays at B A B AR. Markus Cristinziani. WIN’03, Lake Geneva, October 6-11. Outline . Measurements of branching fractions and asymmetries A CP for charmless decays by Babar: B → PP B → PV
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Rare hadronic B decays at BABAR Markus Cristinziani WIN’03, Lake Geneva, October 6-11 Markus Cristinziani, SLAC
Outline • Measurements of branching fractions and asymmetries ACP for charmless decays by Babar: B→PP B→PV B→VV • Discuss results which are challenging theory Markus Cristinziani, SLAC
Motivation • Standard Model is good ! • Look for processes where SM is suppressed to be sensitive to new physics • These are CKM-suppressed decays or penguin dominated processes • Measure and interpret as many channel as possible. Markus Cristinziani, SLAC
Processes at the quark level Penguin Tree π+ π+ π- B0 B0 π- |P/T| ~ 0.3 For a single weak phase: Sππ= sin 2α Cππ= 0 With additional weak phase: Spp= sin 2aeff Cpp≠ 0 Markus Cristinziani, SLAC
Direct CP violation If two distinct strong and weak phases are involved in the decays of the B meson and its charge conjugate CP asymmetry occurs • : strong phase CP-even : weak phase CP-odd Markus Cristinziani, SLAC
(DE) 20 MeV s(mES) 2.6MeV/c2 Kinematical Variables Energy substituted mass Markus Cristinziani, SLAC
Monte Carlo u,d,s,c background Signal Arbitrary Units Fisher Discriminant Background suppression • Event Topology: B’s are produced at rest: • B decays are sphericalqq events are jet-like • Event shape variables are combined through neural network (NN) • or a Fisher discriminant for • additional separation • Also tagging information can be used Maximum likelihood in these variables Blind Analysis Markus Cristinziani, SLAC
B → hh, h=π,K K and BF imply a high penguin contribution Markus Cristinziani, SLAC
B →π0π0 113 fb-1 Maximum Likelihood fit with qq and B-Background: Nππ= 46 Significance of Signal : 4.2 σ including systematics BF = (2.1 ± 0.6 ±0.3)x10-6 Markus Cristinziani, SLAC
Try to extract α from here Gronau, London PRL 65 (1990) 3381: Branching fractions for pp are related by isospin B→ππ0is pure tree diagram One common side of the triangles Need to measure B and B separately Grossman-Quinn bound Does not provide a very useful bound Consider rr → da ~ 200 Markus Cristinziani, SLAC
B → (ηη’)h Branching Fractions involving η´ are high Markus Cristinziani, SLAC
B → (ηη’)V The different scales in the ηη’ branching fraction are interpreted as an interference of two penguin diagrams (Lipkin Phys.Lett.B 254 (1991) 247) Markus Cristinziani, SLAC
B → (ρω)h • B → ρh updated to 113 fb-1 • B → ρp could provide bounds on a through isospin analysis (pentagon relation) • larger BF than in B → pp (x4) • smaller |P/T| ratio • expect CKM suppressed BF(B → ωp) > BF(B → ωK) Markus Cristinziani, SLAC
B → (ρω)h Markus Cristinziani, SLAC
B → VV N(ρρ) = 93 (>5σ) Markus Cristinziani, SLAC
B →φK(*) Pure penguin modes b → sss Measure sin 2β and a probe for New Physics The BF are similar “Small” The same penguin diagram is dominant in PV and VV cases Markus Cristinziani, SLAC
Conclusions • With 89 (113) fb-1 several charmless decays have been measured • Most measurements comply nicely with the Standard Model prediction • Potentially interesting channels include ACP (K+π-), P(φK*), BF(π0π0) • Need more data to test ACP predictions Markus Cristinziani, SLAC