Helicity amplitude analysis of χ cJ → ϕϕ by Ablikim, M, Achasov, MN, Adlarson, P, Albrecht, M, Aliberti, R, Amoroso, A, An, MR, An, Q, Bai, XH, Bai, Y, Bakina, O, Baldini Ferroli, R, Balossino, I, Ban, Y, Batozskaya, V, Becker, D, Begzsuren, K, Berger, N, Bertani, M, Bettoni, D, Bianchi, F, Bloms, J, Bortone, A, Boyko, I, Fischer, K, Gilman, A, Malde, S, Tat, M, Wilkinson, G, Zhang, Y