Universality of subleading corrections for self-avoiding walks in presence of one dimensional defects

We study three-dimensional self-avoiding walks in presence of a one-dimensional excluded region. We show the appearance of a universal sub-leading exponent which is independent of the particular shape and symmetries of the excluded region. A classical argument provides the estimate: $\mathrm{\Delta }=2\nu -1\approx 0.175(1)$. The numerical simulation gives $\Delta = 0.18(2)$.