  We study the connection between radiative energy loss and radiative
p_T-broadening of a high-energy quark or gluon passing through QCD matter. The
generalized Baier-Dokshitzer-Mueller-Peigne-Schiff-Zakharov (BDMPS-Z) formalism
is used to calculate energy loss due to multiple gluon emission. With L the
length of the matter and l_0 the size of constituents of the matter we find a
double logarithmic correction proportional to ln^2(L/l_0) to parton energy loss
due to two-gluon emission. We also show that the radiative energy loss per unit
length -dE/dz = alpha_s N_c < p_T^2 >/12 by carrying out a resummation of the
double logarithmic terms. Here, the transverse momentum broadening <p_T^2> is
obtained by resumming terms proportional to alpha_s ln^2(L/l_0) in Ref. [11].
Our result agrees with that by the renormalization of qhat proposed in Refs.
[13,14].
