LOS ANGELES (AP) — Zac Brown Band have achieved a rare feat. They have been number one on both the Billboard country airplay chart and the mainstream rock chart. Zac Brown Band have had 11 country airplay number-one songs, the latest being “Homegrown.” ”Heavy Is The Head,” their collaboration with Chris Cornell of Soundgarden, tops the mainstream rock chart this week. The only other act to have achieved number-one songs on both charts is Bon Jovi.