Earlier quoted context omitted.
Yes, but just what are those states? I see no explicit hypotheses. The clearest hint that I see is that the calculated dipole moment is 2.3 Ds at 0–60°C, "which is close to the value for ice", and 1.8 Ds at 60–100°C, "which is comparable to that reported for the vapour phase". Lower dipole moment means weaker hydrogen bonding, and less tetrahedral structure.
> Lower dipole moment means weaker hydrogen bonding Wouldn't weaker hydrogen bounding imply on much lower surface tension? There is some smaller tension, but the trend is really tiny.
So I don't think that they've found a new phase of water. Rather, as the title states, they argue that liquid water is a mixture of two states, one ice-like with strong hydrogen bonding and tetrahedral structure, and the other more disordered, gas-like, with weaker hydrogen bonding. It's just that there's something like a figure/ground transition at 50-60°C. Going from islands of "gas-like" structure in a sea of "ice-like" structure, to islands of "ice-like" structure in a sea of "gas-like" structure.