There are a couple of different things in this post.
First an adult should never do anything to a child out of anger.
Second there are laws in the US against child abuse but not corporal punishment per say. So hitting with a fist and breaking a nose or fracturing a jaw would be child abuse, but an open handed slap that leaves a red mark would be within the limits.
Third the schools in the US started giving children "education" about child abuse trying to prevent such abuse - abuse which does happen to some kids. The schools have indoctrinated kids with your parents can't do this and they can't do that. Frankly I think that for small children whose language skills are not yet developed that a little swat on the fanny is a good thing. I also think that some mystery in life is good. (What would happen if my parents got so mad that they totally lost control...) But by the time a child is old enough to start school and be reasoned with, then methods other than corporal punishment should be used.
The "education" problem is a real pickle for adults today. My daughter pulled that on my wife and I. She said that she was going to call the police and report that she was being abused. You can't tell her that she can't call since that would throw gas on the fire. Fortunately I was able to think faster. Ok call. But I'm not leaving the house that I work to pay for. If anybody goes then you'll be removed to a group home until this matter is resolved. It will probably take a 3 or 4 months to resolve. So if that is what you want go ahead and try calling the police. (My daughter was a privileged princess and never abused in any way.)