2026/07/23 by Masaki Yamada
#hep-ph #astro-ph.CO #hep-th
We numerically investigate networks of global ℤN strings with multi-string junctions in a scalar field model whose vacuum manifold is PSU(N)=SU(N)/ℤN. The construction of the model is motivated by the Higgs vacua of mass-deformed N=4 supersymmetric Yang-Mills theory, commonly known as N=1^* theory, and provides a tractable effective description of string networks with baryon-vertex-like junctions. We perform classical lattice simulations of the formation and evolution of these networks in a radiation-dominated universe. For N=2,3,4,5, and 8, we find that the networks approach a scaling regime rather than becoming frustrated. The normalization of the string density grows in proportion to the dimension of the adjoint representation, N2-1, while non-minimal-charge components remain subdominant. These results imply that, at least for N\lesssim 8, the amplitude of the gravitational-wave energy density generated by the cosmic-string network scales as Ω\rm GW∝ μ2 (N2-1)2, where μ is the tension of a unit-charge string.