“It was inevitable, time marching on as it does, and yet it also hard to believe: Half a century has passed since the Beatles touched down in New York for the first time, on Feb. 7, 1964, and seduced the country with three performances on “The Ed Sullivan Show” and a pair of concerts, at the Washington Coliseum and Carnegie Hall. Everything about them — their pudding basic haircuts, their Cardin suits and pointed boots, their sharp, irreverent sense of humor — seemed outlandish, compared with American pop groups. And though their music was firmly rooted — as they were always quick to point out — in American rhythm and blues, soul and rock, they produced a sound that was fresh, energetic and unmistakably their own.”