Can one measure the weak phase of a penguin diagram? art. no. 074020

The b-->d penguin amplitude receives contributions from internal u, c and t quarks. We show that it is impossible to measure the weak phase of any of these penguin contributions without theoretical input. However, it is possi ble to obtain the weak phase if one makes a single assumption involving the hadronic parameters. With such an assumption, one can test for the presenc e of new physics in the b-->d favor-changing neutral current by comparing t he weak phase of B-d(o)-(B) over bar(d)(o) mixing with that of the t-quark contribution to the b -->d penguin amplitude. [S0556-2821(99)00319-7].