Nonuniform symmetry breaking in noncommutative λΦ4 theory -: art. no. 065008

Spontaneous symmetry breaking in noncommutative cutoff lambdaPhi(4) theory has been analyzed by using the formalism of the effective action for composite operators in the Hartree-Fock approximation. It turns out that there is no phase transition to a constant vacuum expectation of the field and the broken phase corresponds to a nonuniform background. By considering <phi(x)>=A cos((Q) over right arrow .(x) over right arrow) the generated mass gap depends on the angles among the momenta (k) over right arrow and (Q) over right arrow and the noncommutativity parameter (theta) over right arrow. The order of the transition is not easily determinable in our approximation.