  We present a statistical study of the non-thermal X-ray emission of 27 young
rotation powered pulsars (RPPs) and 24 pulsar wind nebulae (PWNe) by using the
Chandra and the XMM-Newton observations, which with the high spatial
resolutions enable us to spatially resolve pulsars from their surrounding PWNe.
We obtain the X-ray luminosities and spectra separately for RPPs and PWNe, and
then investigate their distribution and relation to each other as well as the
relation with the pulsar rotational parameters. In the pair-correlation
analysis we find that: (1) the X-ray (2-10 keV) luminosities of both pulsar and
PWN (L_{psr} and L_{pwn}) display a strong correlation with pulsar spin down
power Edot and characteristic age, and the scalings resulting from a simple
linear fit to the data are L_{psr} \propto Edot^{0.92 \pm 0.04} and L_{pwn}
\propto Edot^{1.45 \pm 0.08} (68% confidence level), respectively, however,
both the fits are not statistically acceptable; (2) L_{psr} also shows a
possible weak correlation with pulsar period P and period derivative Pdot,
whereas L_{pwn} manifests a similar weak correlation with Pdot only; (3) The
PWN photon index Gamma_{pwn} is positively correlated with L_{pwn} and
L_{pwn}/Edot. We also found that the PWN X-ray luminosity is typically 1 to 10
times larger than that from the underlying pulsar, and the PWN photon indices
span a range of ~1.5 to ~2. The statistic study of PWN spectral properties
supports the particle wind model in which the X-ray emitting electrons are
accelerated by the termination shock of the wind.
