A method for studying initial geometry fluctuations via event plane correlations in heavy ion collisions

A method is proposed to measure the relative azimuthal angle distributions involving two or more event planes of different order in heavy ion collisions using a Fourier analysis technique. The analysis procedure is demonstrated for correlations involving two and three event planes (Φ_n, Φ_m and Φ_h). The Fourier coefficients of these distributions are found to coincide with previously proposed correlators, such as cos(6Φ₂-6Φ₃) and cos(Φ₁+2Φ₂-3Φ₃) etc., hence the method provides a natural framework for studying these correlators at the same time. Using a Monte Carlo Glauber model to simulate Au+Au collisions with fluctuating initial geometry, we are able to identify several new two- or three-plane correlators that have sizable magnitudes and should be measured experimentally.