2005/11/29 by Robert Fleischer, Fleischer, Robert, Stefan Recksiegel +1
Physics and Astronomy · #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/0511325
4 pages, 2 figures. Contribution to the proceedings of EPS-HEP2005
arxiv created 2005/11/29 · openalex publication_date 2005/11/29 · arxiv updated 2009/12/01 · openalex created_date 2024/04/10 · openalex updated_date 2026/07/28
With the wealth of new data from the B-factories, b -> d penguin decays become available for study, in addition to their b -> s counterparts that have proven an indespensable tool for the exploration of new-physics effects in flavour physics. A prominent example of the b -> d penguin transitions is B0d → K0 K0. We show that this decay can be charaterized in the Standard Model by a surface in the observable space of the direct and mixing-induced CP asymmetries and the branching ratio. The form of this surface, which is theoretically clean, implies a lower bound for the branching ratio that has recently been confirmed experimentally. If future measurements of the CP asymmetries yield a point away from the SM surface, this would be an interesting signal of new physics. We point out that the hadronic parameters in B0d → K0 K0 that parameterize the position on the SM surface are related to hadronic parameters in the B -> pi K system. The fact that the branching ratio of B0d → K0 K0 is very close to its lower bound yields interesting implications for B -> pi K even without knowledge of the CP asymmetries of B0d → K0 K0. The mechanism that produces the lower bound for B0d → K0 K0 is actually much more general; we derive lower bounds for various other b -> d penguin-induced processes, including B -> rho gamma and B^± → K(∗)± K(∗). Some of these theoretical lower bounds are very close to the current experimental upper bounds.