That would interest me, too! I happen to live in France, and the only ES I know is written with an "accent grave" over the "e", i.e. "ès", which is only used in diploma abbreviations meaning "en les" = "in the" e.g. "Docteur ès sciences" or "Licencié ès lettres" --- has nothing necessarily to do with "The Arts". Otherwise of course there's the abb. for Einsteinium! But since two of you have made this connection (& the solution then seems to make sense), perhaps one of you could explain: some secret art movement we mortals have never heard of perhaps? Got nowhere by googling, either. It's your turn now!