They've been working on the follow-up to their breakout (on both sides of the pond) Sigh No More album since early 2011 and have been road-testing new material during a recent run of U.S. summer shows.

But now, finally, Mumford & Sons have given fans a proper taste of what they can expect on their upcoming album. The problem is, they can't seem to settle on a name for the new track.

Called either "Ghosts That We Knew" or, simply, "Ghosts" ("We're not very good at deciding song names," frontman Marcus Mumford laughed, "we'll hash it out, we'll have a physical fight later"), Mumford & Sons unveiled the brand-new song during a performance at Philadelphia station Radio 104.5. Regardless of the title they settle on, there's a pretty good chance their fanbase is going to be rather happy.

Because, frankly, the song is a stunner, rolling along on a rail of acoustic guitar, banjo and accordion, while Mumford keens about a love destroyed ("You saw no fault/ No cracks in my heart/ And you kneel beside/ My hope torn apart/ But the ghosts that we knew, will flicker from view/ Will live a long life") and the misguided hope that all can be repaired ("So give me hope in the darkness/ That I will see the light/ Because oh, it gave me such a fright/ But I will hope as long as you like/ Just promise me we'll be all right"). There's a hushed majesty to it all, a muted sense of despair and grace, and it finds them building on their Bluegrass roots. Shoot, Mumford even replicates the staggered "I-I-I-I" that helped propel "The Cave" to smash status both here in the States and back home in England.

There's still no official release date for the follow-up to Sigh (it is reportedly set for February), but based on "Ghosts," that disc can't come soon enough for Mumford's fans. Hopefully, they'll figure out all the song titles by then.

What are you expecting from the next Mumford album? Let us know in the comments!