A Novel Model-Independent Approach to Explore New Physics in Five-body Semileptonic Decays

We derive three parameters associated with the angular distribution of semileptonic five-body decays D_(s)/B_(s)→ Vℓ^+ν_ℓ (ℓ=e,μ,τ) with V→ PPP, where V and P denote vector and pseudo-scalar particles. These parameters, expected to be unity in the Standard Model, may deviate if new physics is involved. Our model-independent approach involves deriving the specific form of the angular distribution under the most general form of the decay matrix element D_(s)/B_(s)→ V. The outcomes have potential applications in precisely testing the Standard Model and exploring new physics. Relevant measurements can be carried out using data obtained from BESIII, Belle II, and LHCb.