It is definitely not just the end of the Alma Mater, or "theme song" as you put it, and if anything else it has become part of the Alma Mater but not vice versa. The Alma mater is not sung without being followed by the Rock Chalk Chant, but the Rock Chalk Chant is said frequently without the Alma Mater. It is always chanted before a game and then when the game is near the end, if Kansas is clearly going to win, which is most of the time, it is chanted until the clock runs out. So picture the last two minutes of a game, with time outs, with that being chanted over and over. Like I said, the video doesn't do it justice, as it is exceptionally loud when being chanted in the Fieldhouse and/or Memorial Stadium. It rocks the place!