Rome’s Santa Cecilia Orchestra, led by Sir Antonio Pappano, with guest soloist Martha Argerich, visited Symphony Hall on Sunday, October 22nd, performing at the rather unusual hour of 5 p.m. Going into the concert, I was overtaken by the suggestion of my title for this review. Thinking of Lorca and Hemingway, who between them immortalized the phrase “Five in the Afternoon,” in connection with bullfighting, I wondered if we concert goers were in for a strong flavor of doom, transcended through ritual and magnificence. No such thing. The concert was all beauty and vitality, though certainly with magnificence about it.  This stunning event was the best orchestral concert of the fall in Boston.