Neutron-neutron scattering length from the reaction γd → πnn employing chiral perturbation theory V. Lensky, V. Baru, E. Epelbaum, C. Hanhart, J. Haidenbauer, A. Kudryavtsev and U. -G. Meißner Eur. Phys. J. A, 33 4 (2007) 339-348 Published online: 19 September 2007 DOI: 10.1140/epja/i2007-10461-y