In French, Italian there is a particle ba(h) which is used for exclamation of contempt, excitement, surprise etc. There's pretty similar particle բա in Armenian which is used for expressing amusent as well as for strengthening of affirmation - like in phrase "Ba vontc" ("that's for sure").
On the other hand in Proto-Slavic languages there was a particle "bo" - because - which is used as a compound in many words in Russian, Ukrainian, Polish and other Eastern and Western Slavic languages - abo, libo, lub, ibo. Also in Polish, for example, word "bo" is still used by itself.
Moreover, in Lithuanian there's a word "arba" - "or", which is actually exact equivalent of Slavic "або".
Are "exclamation" ba and "conjuction" ba related? If yes, what is the etymology of this particle. In book "Indo-European and its closest relatives" it is claimed that the roots of this word can be found as mush as on pre-PIE level. How valid is this claim fron the point of view of modern linguistics?