We study a problem of constructing an algebraic torus (an abelian variety) over a -adic field whose Néron model would have a given connected commutative unipotent group as the identity component of its special fibre.
Boris KUNYAVSKIĬ. Jean-Jacques SANSUC. "Réduction des groupes algébriques commutatifs." J. Math. Soc. Japan 53 (2) 457 - 483, April, 2001. https://doi.org/10.2969/jmsj/05320457