B s →μ + μ − decay in the R-parity violating minimal supergravity Ashutosh Kumar Alok and Sudhir Kumar Gupta Eur. Phys. J. C, 65 3-4 (2010) 491-500 Published online: 20 October 2009 DOI: 10.1140/epjc/s10052-009-1163-3