Modern Music, a collaboration among pianists Brad Mehldau and Kevin Hays and composer Patrick Zimmerli, blurs the line that separates classical and jazz. (All three have roots playing jazz in Connecticut as teenagers; Zimmerli is also a saxophonist, but he doesn’t perform here.) Mehldau’s work is heavily influenced by classical music, so the acclaimed pianist’s fans shouldn’t be surprised by this project. Zimmerli wrote three of the compositions and arranged the other material, which includes pieces by Mehldau, Hays, Ornette Coleman, Steve Reich, and Philip Glass. The pianists perform the opener, Zimmerli’s melodic “Crazy Quilt,” with clarity and grace; there’s none of the clutter that can mark piano duos. Coleman’s “Lonely Woman” starts with grand chords that create a vibe miles from the original; later the piece’s classic melody emerges, but in a setting that evokes Romanticism more than free jazz. It’s strange to hear improvisation brought to bear on a piano arrangement of an excerpt of Reich’s “Music for 18 Musicians,” but the loose fluidity shines a new light on the well-known pattern music.