In two fully simulated particle-decay channels, fits using a phase-space weighting method — one that assigns corrections at local kinematic points — showed masses, widths and component fractions closer to the values generated in the simulations. The approach is designed to account for detector mass-resolution effects in amplitude analysis: in the simulations, the truth-level quantity and reconstructed observation can differ. The authors’ summary also reports lower resonance-parameter and interference biases, along with fewer artificial structures, in the two applications.
The document is an arXiv version 1 preprint dated 26 August 2026. Its tests use fully simulated Monte Carlo samples — computer-generated events with both truth-level and reconstructed kinematics. Here, “truth-level” means the generated quantities used as the simulation reference.
A local correction for detector smearing
For each observed event, the method estimates the local detector response from nearby truth–reconstruction correspondences in the simulated sample and creates an event-by-event weight that maps true phase space to smeared observation space. The local response estimate typically uses more than about 100 nearby Monte Carlo events, a design intended to suppress statistical fluctuations while keeping the estimate local.
The corrected event weights are then included in a partial-wave-analysis (PWA) fit used here to estimate masses, widths and component fractions. The amplitude model and weights are updated repeatedly until the fitted parameters stabilize within a predefined tolerance. The authors acknowledge residual model dependence because the correction uses an assumed amplitude; iteration is presented as a possible mitigation.
Two tests in simulated decays
The first test modeled a J/ψ decay to Ξ−, Ξ̄+ and π0, with an intermediate Ξ(1530) and a phase-space contribution. In that channel, the weighted distribution was reported to agree more closely with the truth-level distribution. Across weighting iterations, the fitted mass and width became stable and close to truth, while the reported bias in component fractions was lower.
The second test modeled a J/ψ decay to K−, Λ and Ξ̄+, with Ξ(1690), Ξ(1720), non-resonant contributions and mutual interference. The fits assessed mass, width and fraction for the modeled components. The text reports much smaller deviations from generated values after weighting for both Ξ(1690) and Ξ(1720).
The checks behind the reported improvement
The study also examined “pull” distributions, a check of mass, width and fraction fits against their generated values in standardized units. For Ξ(1690), the reported means were −0.14 ± 0.10 for mass, −0.239 ± 0.10 for width and 0.2 ± 0.1 for fraction; the corresponding widths were 1.06 ± 0.07, 0.96 ± 0.07 and 1.01 ± 0.07. For Ξ(1720), the means were 0.02 ± 0.10, −0.28 ± 0.1 and 0.2 ± 0.1, with widths of 0.99 ± 0.07, 1 ± 0.07 and 1.02 ± 0.07. The paper describes both sets as standard Gaussian functions with centers near zero and widths near one.
A result with clear limits
The supplied analysis reports the main improvements qualitatively. It gives no numerical effect size for the bias changes, and no confidence intervals, formal hypothesis tests or p-values are reported.
The evidence is limited to the two fully simulated Monte Carlo decay samples, so it does not establish performance on real experimental data. The authors acknowledge residual dependence on the assumed amplitude model. They also describe extensions to momentum and angular resolution, but those extensions were not quantitatively evaluated in the supplied text.
The authors report minimal computational overhead after reusable weight tables are generated, but the supplied text does not quantify that efficiency claim.
The work was supported in part by the National Key R&D Program of China (Contract 2025YFA1613900), the National Natural Science Foundation of China (Contracts 12225509 and 12475089), and the Guangdong Basic and Applied Basic Research Foundation (2024A1515012416).
Paper data and sources
Original title: A Weighting Method for Incorporating Mass Resolution Effects in Amplitude Analysis
Authors: Benhou Xiang, Wenqian Zheng, Hongxun Yang et al.
Journal/Repository: arXiv
Status: Preprint, not yet peer-reviewed
First online: 2026-08-26
DOI: Not available
Original paper · Full text