“…In a series of papers, Baroni, Colombo and Mingione [3,5,16,17,18] have studied regularity properties of minimizers of these problems, see also [9,46]. Other researchers [15,21] have considered the variant of the double phase functional, F (x, t) ≈ (t − 1) p − + a(x)(t − 1) q − , with (s) − := max{s, 0}, which is degenerate for positive values of the gradient. Furthermore, minimizers of borderline functionals like F (x, t) = t p(x) log(e + t) or F (x, t) = t p + a(x)t p log(e + t) have been recently studied, see for instance [4,9,24,44,45,47].…”