Quintom scenario

The Quintom scenario (derived from the words quintessence and phantom, as in phantom energy) is a hypothetical scenario regarding dark energy, with the equation of state crossing the cosmological constant boundary (${\displaystyle w=-1}$) from above to below, or oppositely. Theoretically, a no-go theorem[1] has been proven, showing that to generate this scenario at least two degrees of freedom are required for dark energy models.