New York: QUICK; FRED; THE FLIT: There are rumors around that this j.5 Britain's revenge for the Poston Tea Party. You guessed it . . . the Beatles have arrived in the United States for their first appearance before an idolizing teen-age crowd; with the St. Vitus bounce. They take an airing in Central Park. No. There is no truth to the buzz that the Zoo's laughing hyena was driven underground.