Evaluation of the systematic uncertainties of the cosmic ray energy spectrum measured by the Telescope Array surface detector array

The surface detector (SD) array of the Telescope Array (TA) experiment, covering an area of 700 km$^2$ with 507 plastic scintillators, observes ultra-high-energy cosmic rays (UHECRs). This study evaluates systematic uncertainties in the energy spectrum measured by the TA SD array, focusing on the impact of hadronic interaction models and primary mass composition. Additionally, we introduce a Bayesian forward-folding framework that incorporates various systematic effects into spectral reconstruction and illustrate the influence of spectral assumptions and composition modeling.