Fractured Dreams, Lera Auerbach’s Fourth Violin Sonata, consists of 18 short musical “dreams.” The piece was premiered by Hilary Hahn together with the composer in the summer of 2019, shortly before the American violinist took a year-long sabbatical that was involuntarily extended by the pandemic. Now Fractured Dreams is back on the program for Hahn’s Pierre Boulez Saal debut, once again with Auerbach at the piano. The two artists also perform works by Sergei Prokofiev—whose music has played a significant role in both of their careers.