Multisymplectic formalism for cubic horndeski theories

We present the covariant multisymplectic formalism for the so-called cubic Horndeski theories and discuss the geometrical and physical interpretation of the constraints that arise in the uni¿ed Lagrangian-Hamiltonian approach. We analyse in more detail the covariant Hamiltonian formalism of these theories and we show that there are particular conditions that must be satis¿ed for the Poincar´e-Cartan form of the Lagrangian to project onto J1p. From this result, we study when a formulation using only multimomenta is possible. We further discuss the implications of the general case, in which the projection onto J1p conditions are not met.The authors acknowledge financial support from the Ministerio de Ciencia, Innovación y Universidades (Spain), projects PGC2018-098265-B-C33 and D2021-125515NB-21Peer ReviewedPostprint (author's final draft