  Using the RossiXTE experiment, we detect weak X-ray emission from the
recurrent Be/X-ray transient A 0535+26 at a time when the optical counterpart
V725 Tau displayed H-alpha in absorption, indicating the absence of a
circumstellar disc. The X-ray radiation is strongly modulated at the 103.5-s
pulse period of the neutron star, confirming that it originates from A 0535+26.
The source is weaker than in previous quiescence detections by two orders of
magnitude and should be in the centrifugal inhibition regime. We show that the
X-ray luminosity cannot be due to accretion on to the magnetosphere of the
neutron star. Therefore this detection represents a new state of the accreting
pulsar. We speculate that the X-ray emission can be due to some matter leaking
through the magnetospheric barrier or thermal radiation from the neutron star
surface due to crustal heating. The observed luminosity is probably compatible
with recent predictions of thermal radiation from X-ray transients in
quiescence. The detection of the X-ray source in the inhibition regime implies
a reduced density in the outflow from the Be companion during its disc-less
phase.
