title: B-->pipi, new physics in B-->piK, and implications for rare K and B decays.
abstract: The measured B-->pipi,piK branching ratios (BRs) exhibit puzzling patterns. We point out that the B-->pipi hierarchy can be nicely accommodated in the standard model (SM) through nonfactorizable hadronic interference effects, whereas the B-->piK system may indicate new physics (NP) in the electroweak (EW) penguin sector. Using the B-->pipi data and the SU(3) flavor symmetry, we fix the hadronic B-->piK parameters and show that any currently observed feature of the B-->piK system can be easily explained through enhanced EW penguin diagrams with a large CP-violating NP phase. This in turn implies in particular an enhancement of the K(L)-->pi(0)nunu rate by 1 order of magnitude, with BR(K(L)-->pi(0)nunu) approximately 4BR(K+-->pi(+)nunu), BR(K(L)-->pi(0)e(+)e(-))=O(10(-10)), and (sin(2beta)(pinunu)<0. We address also other rare K and B decays and B(d)-->phiK(S).
authors.affiliation: Physik Department, Technische Universität München, D-85748 Garching, Germany.
authors.forename: Andrzej J
authors.initials: AJ
authors.lastname: Buras
authors.forename: Robert
authors.initials: R
authors.lastname: Fleischer
authors.forename: Stefan
authors.initials: S
authors.lastname: Recksiegel
authors.forename: Felix
authors.initials: F
authors.lastname: Schwab