On ‘light’ fermions and proton stability in ‘big divisor’ D3/D7 large volume compactifications Aalok Misra and Pramod Shukla Eur. Phys. J. C, 71 6 (2011) 1662 Published online: 01 June 2011 DOI: 10.1140/epjc/s10052-011-1662-x