Theory of Zeeman level widths of nuclear spins in solid orthohydrogen

The Zeeman level widths of nuclear spins in solid orthohydrogen are calculated. The treatment is based on an equation for the nonequilibrium mean values of the operators characterizing the nonequilibrium state of the spin system, which interacts with the libron system (treated as a thermal bath). This equation is derived by the method of Zubarev's nonequilibrium statistical operator. The correlation functions for the libron subsystem that occur in the expression for the widths are calculated in the Bose approximation.