Instead of asking here where you get the dumb answers to questions from guys that have no clue about what the CA, AZ, NM or Texas laws are, you might want to ask either in the Legal forum or the State Forums. Might get some better and more accurate answers.
They are trespassing. You might not be guilty of brandishing if you didn't threaten. (As far as I can tell "brandishing" in CA is only unlawful with an imitation firearm) You can carry a loaded firearm on your land, you can carry a loaded firearm when making an arrest, and you can carry while waiting for the authorities to arrive after notifying them that a crime is in progress.
Then you get into areas if you draw down, if you can't show that you felt threatened. In other words a couple of grandmas and little kids wouldn't cut it, 30 young farmworkers, would probably be easy to show you felt threatened.
In other words up until you did something really stupid, you wouldn't be breaking the law.