Resumen: The invariant balanced Hermitian geometry of nilmanifolds of dimension 6 is described. We prove that the (restricted) holonomy group of the associated Bismut connection reduces to a proper subgroup of SU(3) if and only if the complex structure is abelian. As an application we show that if J is abelian, then any invariant balanced J-Hermitian structure provides solutions of the Strominger system. Idioma: Inglés DOI: 10.1515/forum-2012-0072 Año: 2015 Publicado en: FORUM MATHEMATICUM 27, 2 (2015), 1025-1070 ISSN: 0933-7741 Factor impacto JCR: 0.823 (2015) Categ. JCR: MATHEMATICS, APPLIED rank: 124 / 254 = 0.488 (2015) - Q2 - T2 Categ. JCR: MATHEMATICS rank: 88 / 311 = 0.283 (2015) - Q2 - T1 Factor impacto SCIMAGO: 0.918 - Mathematics (miscellaneous) (Q2) - Applied Mathematics (Q2)