Well if this Batman has a theme it's not great enough for me to know it. Look at Indiana Jones, Superman, James Bond all have iconic, recognisable, grand themes.
The same can't really be said about this Batman mostly becuase I think the music and score is uninspired.
I like the USE of music in this movie, the action scenes aren't overblown with it, infact, the music is almost absent in the action scenes, but a great, grand, theme is needed for Batman.
Straining to think about I think I can scarely hear it my head but it's not something grand and awesome that you can hum/vocalize out loud like Superman's theme or Indy's.
I think part of the problem is that you want the score to be something that it's not.
Composers like Williams and Elfman both write film music in a Romantic vein, full of the Wagnerian motifs you're calling "themes."
Zimmer and Howard's scores for both of Nolan's Batman movies are far more minimalist.
a Batman "theme," and it's quite distinctive, when you hear it. But it's just two long notes in the background, like a hunting horn: naa-NAA. My knowledge of music theory is relatively limited, and my ear is not altogether reliable, but I believe the interval between the two is called a "perfect fourth". It's heavy, slow, and somber.
By comparison, Elfman's six-note Batman theme sounds busy and corny, especially when played quickly, on brass instruments: ba-ba-ba-BAAAT-man...ba-ba-ba-bat...bat-MAN! It works in the context of Elfman's score, but it would have stood out like a sore thumb in Batman Begins
or The Dark Knight
To me, Elfman's theme evokes Batman rushing around and beating up the bad guys--sock! pow! biff! bam! Whereas those two notes in Zimmer and Howard's theme evoke Batman perched on top of a building, looking down at Gotham City by night, contemplating his next move, or perhaps just brooding about how tortured and emo he is.