The Painlevé test for sigma models

Abstract

We test the sigma models for the Painlevé property. While the construction of finite action solutions ensures their meromorphicity, the general case requires testing. The test is performed for the equations in the homogeneous variables, with their first component normalised to one. No constraints are imposed on the dimensionality of the model or the values of the initial exponents. This makes the test nontrivial, as the number of equations and dependent variables are indefinite. The system proves to have a (4N − 5)-parameter family of solutions whose only movable singularities are poles, while the order of the investigated system is 4N − 4. The remaining degree of freedom, connected with an extra negative resonance, may correspond to a branching movable essential singularity. An example of such a solution is provided.