Unless you’re listening to an iPod, you probably don’t associate your train ride with jazz. But this Sunday, Chicago jazz guitarist Neal Alger will play live on a special Chi-Jazz El train traveling from the Loop to Evanston along the purple line, accompanied by Brian Gephart on sax and Mike Arnopol on bass. It’s a partnership between the Mayor’s Office of Special Events and the Jazz Institute of Chicago. A CTA historian will also be there to point out historic sites along the way.