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Constraints on from Charmless Two- Body B Decays: Status and Perspectives James D. Olsen Princeton University Workshop on the CKM Unitarity Triangle Second Meeting, IPPP Durham April 5-9, 2003

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CKM Workshop 2003 J. Olsen 2 Overview is the weak phase difference between b u tree and b s penguin amplitudes Large penguin contributions facilitate sensitivity to One physicists garbage (penguin pollution) is anothers gold! Challenges Strong phase difficult to calculate Electroweak penguins (EWP) Rescattering All two-body modes are useful K sensitivity to A( 0 ) ~ T, cross-check kinematic assumptions (A CP in 0 ) KK constraints on rescattering

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CKM Workshop 2003 J. Olsen 3 General Strategies Use SU(2) symmetry Relate decay rates for all K modes (use R ratios of BFs) Assuming negligible annihilation amplitudes, K 0 pure P Use A CP to remove dependence on strong phase Provides allowed regions in R vs. Use a model QCD FA, PQCD, Charming Penguins, etc Pitfalls? Electroweak penguins (EWP) Can be included; constrained by asmmetry in Rescattering Use decay rates for KK modes to constrain rescattering effects

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CKM Workshop 2003 J. Olsen 4 Experimental Considerations Charmless decays are Cabibbo suppressed ( |V ub | 2 ) BF(B KK) ~ 10 -8 - 10 -6, BF(B ) ~ 10 -6, BF(B K ) ~ 10 -5 Background dominated by At the (4S) can use kinematics and topology to separate spherical B decays from jetty light-quark production Particle ID is critical ( /K separation) BaBar Detector of Internally Reflected Cherenkov Light Belle Aerogel Dominant sources of systematic error (now) BF: PDF shapes, efficiency A CP : PDF shapes, possible detector charge bias

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CKM Workshop 2003 J. Olsen 5 Data: B K K+-K+- K0+K0+ BaBar BaBar Belle CLEO 81 78 15 BF(10 -6 )

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CKM Workshop 2003 J. Olsen 6 Data: B K K+0K+0 K00K00 Belle BaBar Belle CLEO 81 78 15

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CKM Workshop 2003 J. Olsen 7 Data: B Fit region Belle +-+- 0000 BaBar BaBar Belle CLEO 81 78 15 Br(B 0 Br(B 0 )?

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CKM Workshop 2003 J. Olsen 8 Data: B KK K+K-K+K- K+K0K+K0 K0K0K0K0 Belle BaBar PID cross-feed BaBar Belle CLEO 81 78 15 No sign of B KK

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CKM Workshop 2003 J. Olsen 9 Summary of Branching Fractions * weighted average (speakers calculation) *

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CKM Workshop 2003 J. Olsen 10 The penguins are out there If trees dominate in we would have: Data: first ratio is 0.25 0.08, second is 2.1 0.4 Destructive P/T interference in Color-suppressed tree in 0 ? If penguins dominate in K we would have: Data:

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CKM Workshop 2003 J. Olsen 11 Constraints on P/T Use data P from K 0 + Two-body BFs S and C CKM indirect constraint on BaBar prefers: 0.1 < |P/T| < 0.4 -170 < arg(P/T) < -40 Belle prefers: 0.5 < |P/T| < 1.1 -70 < arg(P/T) < -30 P/T Arg(P/T) Belle BaBar P/T

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CKM Workshop 2003 J. Olsen 12 Is Rescattering Important? Could modify branching fractions and CP asymmetries in and K decays, complicating extraction of and KK decays are more sensitive to rescattering Could have significant enhancement through (for example) DD or intermediate states BaBarPQCD * K+K-K+K-