What if Radiohead had used their Nineties digital prog to escape into the past rather than fight the future? That’s the vibe of “3WW,” the prettily mordant first track on Alt-J’s third record, a glitch-y modern version of Fairport Convention’s folk pastorales. The U.K. art rockers have a nice time messing with history – their “House of the Rising Sun” is a minimalist chamber rumble, with singer-guitarist Joe Newman adding his own poetry to the original. At times their idea-heavy songs can feel weighed down by cleverness (the Primus-y “Deadcrush”). But Alt-J can create a dark beauty that’s like moonlight on an English moor.