A Weighting Method for Incorporating Mass Resolution Effects in Amplitude Analysis

Abstract

We present a phase-space weighting method for incorporating detector mass-resolution effects into amplitude analysis in an efficient and flexible way. The method uses fully simulated Monte Carlo samples containing both truth-level and reconstructed kinematics to estimate the local detector response around each observed event. Based on these truth-reconstruction correspondences, event-by-event weights are constructed to map theoretical amplitudes from the true phase space to the smeared observational space. In this way, detector smearing can be included in the likelihood fit without performing an explicit multidimensional convolution or on-the-fly detector simulation. The procedure naturally handles nonuniform resolution across the Dalitz plane and can be extended beyond invariant masses to momentum and angular variables. Applied to the decays $J/ψ\rightarrow Ξ^{-} \barΞ^{+}π^0$ and $J/ψ\rightarrow K^-Λ\barΞ^+$, the method significantly reduces biases in fitted resonance parameters and interference patterns, suppresses artificial structures, and improves the reliability of partial-wave analysis and resonance spectroscopy in high-precision hadron experiments.