Direct and Indirect Capture of Weakly Interacting Massive Particles by the Earth

The capture of weakly interacting massive particles (WIMPs) by the Earth is calculatd taking account of corrections due to the Earth's motion deep within the potential well of the Sun. Two distinct types of capture are evaluated: first, direct capture of WIMPs out of the Galactic halo; second, indirect capture of WIMPs which had previously interacted with the Earth and had lost enough energy to go into solar orbit, but not enough to be directly captured. It is found that the capture 'resonances' (peaked where the WIMP mass is matched to the mass of some nucleus well-represented in the Earth) are enlarged and broadened by these corrections. General methods are developed for analyzing the propagation of the anisotropies of a nonrelativistic distribution in a central potential.