Revealing new physics in $${\varvec{B}}^{0}_{s}\rightarrow D_s^{\mp } K^{\pm }$$ decays

Abstract The $$B^0_s\rightarrow D_s^{\mp } K^{\pm }$$ B s 0 → D s ∓ K ± system offers a determination of the Unitarity Triangle angle $$\gamma $$ γ . Intrigued by an LHCb analysis showing a surprisingly large result in tension with information on the Unitarity Triangle and other $$\gamma $$ γ measurements, we make a transparent study of the measured observables, confirming the LHCb picture. The corresponding $$\gamma $$ γ puzzle at the $$3\sigma $$ 3 σ level would require CP-violating contributions of New Physics, which should also manifest themselves in the corresponding decay branching ratios. Indeed, we find that the rates of the individual $$B^0_s\rightarrow D_s^{\mp } K^{\pm }$$ B s 0 → D s ∓ K ± channels show puzzling patterns, in accordance with similar decays, with tensions up to $$4.8\sigma $$ 4.8 σ , thereby making the situation much more exciting. We present a formalism to include New-Physics effects in a model-independent way and apply it to the data to constrain the corresponding parameters. Interestingly, new contributions of moderate size could accommodate the data. Utilising this formalism in the future high-precision B physics era may allow us to finally establish new sources of CP violation.