“…In the temperature - 3 He concentration plane (T, x) the line of second-order superfluid transitions T s (x) meets the boundary of the two-phase coexistence region at the tricritical point (T t ≈ 87mK, x t ≈ 0.67); x = N 3 /(N 3 + N 4 ), where N i , i = 3, 4, denotes the number of atoms of 3 He or 4 He, respectively. In this paper we consider a simple lattice model known in the literature as the Vectoralized Blume-Emery-Griffiths model (VBEG) [15,16]. It is defined in Sec.…”