What saxophonist did bandeoneon player and "nuevo tango" pioneer Astor Piazzolla collaborate with on his album Summit?
Summit (album): Summit is an album by Argentinean bandoneonist Astor Piazzolla and jazz saxophonist Gerry Mulligan. Astor Piazzolla:  His oeuvre revolutionized the traditional tango into a new style termed "nuevo tango", incorporating elements from jazz and classical music.
Gerry Mulligan