Resumo
In this work we made a quick study on some basic results related to Groups and Lie Algebras,
action of Groups and Fiber Bundles with the objective of defining connections in Principal Bundles
and, later, in Associated Vector Bundles. Once these concepts are understood, in the main part of this
work, following the article Stability and Isolation Phenomena for Yang-Mills Fields by J.P. Bourguignon
and H. B. Lawson Jr., we developed the “geometric environment” and defined the Yang-Mills
Functional in order to demonstrate a stability result, namely: every weakly stable Yang-Mills field on
S4 with structure group G = SU(2),SU(3),U(1) or U(2) is self-dual or anti-self-dual.