Leading low-energy effective action in 6D, N= (1 1) SYM theory

We elaborate on the low-energy effective action of 6D,N= (1 1) supersymmetric Yang-Mills (SYM) theory in the N= (1 0) harmonic superspace formulation. The theory is described in terms of analytic N= (1 0) gauge superfield V⁺⁺ and analytic ω-hypermultiplet, both in the adjoint representation of gauge group. The effective action is defined in the framework of the background superfield method ensuring the manifest gauge invariance along with manifest N= (1 0) supersymmetry. We calculate leading contribution to the one-loop effective action using the on-shell background superfields corresponding to the option when gauge group SU(N) is broken to SU(N − 1) × ϒ(1) ⊂ SU(N). In the bosonic sector the effective action involves the structure ∼F2X2 , where F⁴ is a monomial of the fourth degree in an abelian field strength F_{M N} and X stands for the scalar fields from the ω-hypermultiplet. It is manifestly demonstrated that the expectation values of the hypermultiplet scalar fields play the role of a natural infrared cutoff.