Anatomy of $B^{0}_{s,d} to J/psi f_{0}(980)$

The (B^{0}_{s}to J/psi f_{0}(980)) decay offers an interesting experimental alternative to the well-known (B^{0}_{s}to J/psi phi) channel for the search of CP-violating New-Physics contributions to (B^{0}_{s})–(bar{B}^{0}_{s}) mixing. As the hadronic structure of the f ₀(980) has not yet been settled, we take a critical look at the implications for the relevant observables and address recent experimental data. It turns out that the effective lifetime of (B^{0}_{s}to J/psi f_{0}(980)) and its mixing-induced CP asymmetry S are quite robust with respect to hadronic effects and thereby allow us to search for a large CP-violating (B^{0}_{s})–(bar{B}^{0}_{s}) mixing phase ? _s , which is tiny in the Standard Model. However, should small CP violation, i.e. in the range ?0.1?S?0, be found in (B^{0}_{s}to J/psi f_{0}(980)), it will be crucial to constrain hadronic corrections in order to distinguish possible New-Physics effects from the Standard Model. We point out that (B^{0}_{d}to J/psi f_{0}(980)), which has not yet been measured, is a key channel in this respect and discuss the physics potential of this decay.