This morning I had to cut this branch for safety purposes. It's from a neighbor's tree.
Can I regrow it?
The longer you leave it sitting where it is in the picture, dehydrating, the less likely it is to grow!
Since it's the wrong time of year to take hardwood cuttings (which appears to be what your branch is) I would just try cutting off the top 18 inches (50 cm) and stick it in a deep container of water - something like a 1-liter plastic bottle with the neck cut off. You want about half the length of the cutting in the water.
Take off all the leaves below the water level. Take all the flowers off as well - you don't want it to waste its energy trying to set seed instead of growing roots.
If you get lucky, it will grow some roots in a few weeks. If nothing happens within say 3 months, or it has obviously died, give up.