Keane collaborating with rappers? On their fourth album, the erstwhile Brit-pop whimperers join forces with K’Naan on “Stop for a Minute,” where the Canadian MC rhymes while Tom Chaplin belts out one of the band’s patented big, cresting choruses. Even better — and weirder — is “Ishin Denshin,” a sprightly synth-propelled ditty with vocal help from Japanese baile-funk singer Tigarah. Elsewhere, there is brass-bolstered soul, electro-flavored dance pop and other un-Keane-like songs. The band can still deliver the angsty goods (check out the gusty “My Shadow”), but Keane have proved themselves masters of — gasp! — pop perkiness.