LONDON, June 12: British folk-rockers Mumford & Sons have canceled three sell-out concerts in the United States this week after announcing on Tuesday that bassist Ted Dwane needed emergency surgery for a blood clot on the brain. The band, which won Album of the Year for “Babel” at the Grammy awards in February and the British Group award at BRIT awards, said Dwane had felt unwell for a few days and was taken to hospital on Monday for emergency treatment. (AGENCIES)