Not a lot of girls can ooze sex appeal in a t-shirt and sweatpants decorated with dice, but the lead singer of Marina and the Diamonds owned the crowd Saturday at South by Southwest. I’m not sure I would’ve gotten her if I had only listened to her record, but, live, she definitely glowed with that elusive, rock-star charisma. We caught two acts at the Chop Shop/Atlantic Records tent and both were pretty kick-ass. The other act (which also happened to be British) was Scars on 45, a rocking band with a dose of folk and a dose of Oasis. Not sure if I loved these bands because the Chop Shop/Atlantic tent was warm and felt like a hug after walking through the bracing wind and uncommonly chilly 40-degree weather. Or maybe I liked them because I saw a lot of disappointing acts the day before. Chop Shop licenses music and has been known for “breaking” bands on TV shows like CSI. Gotta give an old-school label like Atlantic credit for working a new path of market-testing. Do Chop Shop favorites get an Atlantic deal upstream? Is that the tail wagging the dog?