We present the results of a search for rapidly evolving transients in the Dark Energy Survey Supernova Programme .
These events are characterized by fast light curve evolution ( rise to peak in \lesssim 10 d and exponential decline in \lesssim 30 d after peak ) .
We discovered 72 events , including 37 transients with a spectroscopic redshift from host galaxy spectral features .
The 37 events increase the total number of rapid optical transients by more than factor of two .
They are found at a wide range of redshifts ( 0.05 < z < 1.56 ) and peak brightnesses ( -15.75 > M _ { \mathrm { g } } > -22.25 ) .
The multiband photometry is well fit by a blackbody up to few weeks after peak .
The events appear to be hot ( T \approx 10000 - 30000 K ) and large ( R \approx 10 ^ { 14 } -2 \cdot 10 ^ { 15 } cm ) at peak , and generally expand and cool in time , though some events show evidence for a receding photosphere with roughly constant temperature .
Spectra taken around peak are dominated by a blue featureless continuum consistent with hot , optically thick ejecta .
We compare our events with a previously suggested physical scenario involving shock breakout in an optically thick wind surrounding a core-collapse supernova ( CCSNe ) , we conclude that current models for such a scenario might need an additional power source to describe the exponential decline .
We find these transients tend to favor star-forming host galaxies , which could be consistent with a core-collapse origin .
However , more detailed modeling of the light curves is necessary to determine their physical origin .