The energy-momentum tensor of the massless scalar field is calculated from the
transformation
:

if
and
(Vendrell (1997a)). The black hole emits thus
spontaneously a thermal radiation (Hawking (1975)) of temperature

To the first loop approximation, the back-reaction of the massless radiation on
space-time is analysed by adding to eq.1 the trace anomaly
. One obtains

where
. The mass and temperature of the black hole are renormalised and
become smaller

The radius
of the black hole becomes larger.