Subleading penguin effects in b→ccs transitions impacting 2β(s) determinations

Determine the effects of subleading contributions from highly suppressed penguin diagrams in b→ccs transitions on the precision determination of the CP-violating weak phases 2β and 2βs obtained from time-dependent CP asymmetries in beauty decays, so that these contributions can be fully understood and reliably controlled in the extraction of these phases.

Background

Beauty decays to charmonium final states governed by b→ccq transitions are central to precision studies of CP violation. The weak phases 2β and 2βs are determined from time-dependent CP asymmetries in channels such as B0→J/ψK0 and Bs0→J/ψK+K−, respectively, providing stringent tests of the Standard Model.

However, subleading penguin contributions in b→ccs transitions can bias these determinations. The authors note that these effects are difficult to calculate reliably and must be fully understood for more precise tests. They highlight that measurements in penguin-enhanced b→ccd modes (e.g., B+→J/ψπ+) can help control these contributions, underscoring the unresolved status of quantifying the penguin impact on 2β(s).