Where could I obtain the rights to a piece of music by Gy=?UTF-8?B?w7Y=?=rgy Ligeti?

Where could I obtain the rights to a piece of music by György Ligeti?

I am looking to obtain the right to use "Lontano" by György Ligeti in
a short film. I'm wondering who owns the right to the music? Is the
sheet music in the public domain? If so, are there any royalty free
versions available? If not, do you know of any lesser orchestras that
have performed it? I doubt any major orchestra will allow be to use
their recording, let alone write back to me. Hopefully someone could
help, I haven't had any luck so far.