Spin dynamics simulation in muon accelerator

One of the major problems in particle physics is the discrepancy of the anomalous magnetic moment of muons (g − 2) between the experimental and theoretical value about 3.7 σ. This discrepancy suggests the physics beyond the standard model, and should be verified by an experiment with improved accuracy. We plan to conduct a different experiment at J-PARC than the previous one at the Brookhaven. This experiment for the muon g − 2 is to measure the muon spin dynamics, and it is important to understand the spin dynamics leading up to the measurement. In particular, our study shows that the correlation between momentum and spin direction systematically shifts the measured muon g − 2 value. In order to understand the momentum-spin correlation, it is necessary to understand the spin dynamics in the muon linear accelerator. Conventional simulations of the muon linear accelerator have been performed using multiple software programs, which have not been able to simulate spin dynamics. In order to solve this problem, an extension program using the General Particle Tracer (GPT) has been developed to calculate the spin dynamics. In this presentation, we will present the methods and results of the spin dynamics simulation of the muon linear accelerator using GPT. (author)