  We explain the axisymmetric gaps seen in recent long-baseline observations of
the HL Tau protoplanetary disc with the Atacama Large Millimetre/Submillimetre
Array (ALMA) as being due to the different response of gas and dust to embedded
planets in protoplanetary discs. We perform global, three dimensional dusty
smoothed particle hydrodynamics calculations of multiple planets embedded in
dust/gas discs which successfully reproduce most of the structures seen in the
ALMA image. We find a best match to the observations using three embedded
planets with masses of 0.2, 0.27 and 0.55 $M_{\rm J}$ in the three main gaps
observed by ALMA, though there remain uncertainties in the exact planet masses
from the disc model.
