Magnetic excitations of the classical spin liquid MgCr2O4 by Bai, X, Paddison, JAM, Kapit, E, Koohpayeh, SM, Wen, J-J, Dutton, SE, Savici, AT, Kolesnikov, AI, Granroth, GE, Broholm, CL, Chalker, JT, Mourigal, M