FIG. 1 is a left front perspective view of a head lamp showing our new design; FIG. 2 is a front elevational view thereof; FIG. 3 is a rear elevational view thereof; FIG. 4 is a right side elevational view thereof; FIG. 5 is a left side elevational view thereof; FIG. 6 is a top plan view thereof; and, FIG. 7 is a bottom plan view thereof. The broken lines illustrate environmental structure and form no part of the claimed design.