Legal Question in Administrative Law in California

Is what a legal alias? Your birth name? The name you've used for 40 years? Something else?

California pretty much allows a person to adopt and use whatever name they want. Sure, there is a formal process for legal name change. Nevertheless, it is also permissible to change your name without using the legal process, so long as you don't defraud anyone or use the name change to avoid prosecution.

If you are having an actual problem now, after 40 years, related to your change of name, you need to tell us what the nature of the problem is, not just ask whether something or other is a legal alias. We can't work on your problem for you without knowing who is challenging your name choice, and why.