Is it possible to fix

it looks repairable but i am not sure if that is a diaphragm or a filter type material that is torn.

If it is just a filter it should be a rather easy fix, just a little glue, but if it is a diaphragm, it is doubtful it will be fixed

Not sure if it is worth it but you can get a replacement from

http://www.sennheiserusa.com/serviceandsupport_part-finder

~65USD

Have you tried gluing the part back into its place?  Did you tear the diaphram as well or what?  As long as you have not torn the diaphram or dislodged the voice coil from it, that looks repairable.

It is repairable, BUT you must get the pieces perfectly mated together or the coil will rub the magnet housing. Before trying to glue it, set the plastic in place, see if it fits well, and you might try passing an audio signal through it to see if it distorts unusually. If not, you should be able to glue it back in place but I don't know what the best glue to use would be. Not superglue, the fumes from it can deposit on the diaphram though I don't know if pointing a fan at it while it dried would help or hurt. Maybe some epoxy instead, so it hardens by chemical interaction rather than evaporation.

mono, superglue should be fine for something like this, CA fumes tend to rise' and if he glues it together like its sitting in the picture, it shouldnt be a problem. 

i have fixed things like this before, get it perfectly centered back into place, shouldnt be too difficult looking at how it broke, and then wick a few drops of superglue back into the cracks. check to see that the coil does not rub the magnet (youll hear it). if its good to go, and the diaphragm moves freely without restriction, dab some more superglue on there for good measure (Dont go overboard and get it on the diaphragm). and try not to break it again.