Methods for Measuring New-Physics Parameters in B Decays

Recently, it was argued that new-physics (NP) effects in B decays can be approximately parametrized in terms of a few quantities. As a result, CP violation in the $B$ system allows one not only to detect the presence of new physics (NP), but also to measure its parameters. This will allow a partial identification of the NP, before its production at high-energy colliders. In this paper, we examine three methods for measuring NP parameters. The first uses a technique involving both $\btos$ and $\btod$ penguin B decays. Depending on which pair of decays is used, the theoretical error is in the range 5--15%. The second involves a comparison of $B\to \pi K$ and $B\to\pi\pi$ decays. Although the theoretical error is large ($\gsim 25$), the method can be performed now, with presently-available data. The third is via a time-dependent angular analysis of $\bvv$ decays. In this case, there is no theoretical error, but the technique is experimentally challenging, and the method applies only to those NP models whose weak phase is universal to all NP operators. A reliable identification of the NP will involve the measurement of the NP parameters in many different ways, and with as many B decay modes as possible, so that it will be important to use all of these methods.