Alt-J (∆)‎

Alt-J (also known as ∆) is an English indie rock quartet, formed in 2007 in Leeds, England. Their ‎debut album “An Awesome Wave” was released in May 2012 in Europe and September 2012 in the ‎United States and won the 2012 British Barclaycard Mercury Prize.‎

http://en.wikipedia.org/wiki/Alt-J