  The Herschel Gould Belt Survey key project mapped the bulk of nearby
star-forming molecular clouds in five far-infrared bands with the aim of
compiling complete census of prestellar cores and young, embedded protostars.
In this paper, we present the catalogue of the dense cores and YSOs/protostars
extracted from the Herschel maps of the Lupus I, III, and IV molecular clouds.
The physical properties of the detected objects were derived by fitting their
spectral energy distributions. A total of 532 dense cores, out of which 103 are
presumably prestellar in nature, and 38 YSOs/protostars have been detected in
the three clouds. Almost all the prestellar cores are associated with filaments
against only about one third of the unbound cores and YSOs/protostars.
Prestellar core candidates are found even in filaments that are on average
thermally sub-critical and over a background column density lower than that
measured in other star forming regions so far. The core mass function of the
prestellar cores peaks between 0.2 and 0.3 solar masses and it is compatible
with the log-normal shape found in other regions. Herschel data reveal several,
previously undetected, protostars and new candidates of Class 0 and Class II
with transitional disks. We estimate the evolutionary status of the
YSOs/protostars using two independent indicators: the $\alpha$ index and the
fitting of the spectral energy distribution from near- to far-infrared
wavelengths. For 70% of the objects, the evolutionary stages derived with the
two methods are in agreement. Lupus is confirmed to be a very low-mass
star-forming region, both in terms of the prestellar condensations and of the
diffuse medium. Noticeably, in the Lupus clouds we have found star formation
activity associated with interstellar medium at low column density, usually
quiescent in other (more massive) star forming regions.
