Context : In recent years evidence has been building that planet formation starts early , in the first \sim 0.5 Myr .
Studying the dust masses available in young disks enables understanding the origin of planetary systems since mature disks are lacking the solid material necessary to reproduce the observed exoplanetary systems , especially the massive ones .

Aims : We aim to determine if disks in the embedded stage of star formation contain enough dust to explain the solid content of the most massive exoplanets .

Methods : We use Atacama Large Millimeter/submillimeter Array ( ALMA ) Band 6 ( 1.1 – 1.3 mm ) continuum observations of embedded disks in the Perseus star-forming region together with Very Large Array ( VLA ) Ka-band ( 9 mm ) data to provide a robust estimate of dust disk masses from the flux densities measured in the image plane .

Results : A strong linear correlation between the ALMA and VLA fluxes is observed , demonstrating that emission at both wavelengths is dominated by dust emission .
For a subsample of optically thin sources , we find a median spectral index of 2.5 from which we derive the dust opacity index \beta = 0.5 , suggestive of significant dust growth .
Comparison with ALMA surveys of Orion shows that the Class I dust disk mass distribution between the two regions is similar , but that the Class 0 disks are more massive in Perseus than those in Orion .
Using the DIANA opacity model including large grains , with a dust opacity value of \kappa _ { 9 mm } = 0.28 cm ^ { 2 } g ^ { -1 } , the median dust masses of the embedded disks in Perseus are 158 M _ { \oplus } for Class 0 and 52 M _ { \oplus } for Class I from the VLA fluxes .
The lower limits on the median masses from ALMA fluxes are 47 M _ { \oplus } and 12 M _ { \oplus } for Class 0 and Class I , respectively , obtained using the maximum dust opacity value \kappa _ { 1.3 mm } = 2.3 cm ^ { 2 } g ^ { -1 } .
The dust masses of young Class 0 and I disks are larger by at least a factor of 10 and 3 , respectively , compared with dust masses inferred for Class II disks in Lupus and other regions .

Conclusions : The dust masses of Class 0 and I disks in Perseus derived from the VLA data are high enough to produce the observed exoplanet systems with efficiencies acceptable by planet formation models : the solid content in observed giant exoplanets can be explained if planet formation starts in Class 0 phase with an efficiency of \sim 15 % .
A higher efficiency of \sim 30 % is necessary if the planet formation is set to start in Class I disks .