About a quarter of a century ago, it was shown that nuclei deform from spheres to cylinders, slabs, cylindrical holes and spherical holes as the density increases to ∼1014 g/cm3 the density of the uniform nuclear matter. These canonical pasta phases have been explicitly evaluated or implemented in many calculations, however other structures may exist. In this paper we discuss the gyroid morphology, a periodic bicontinuous structure that has also been observed in block copolymers. Earlier works used the liquid drop model to study the canonical pasta phases. Hence, we will study the gyroid morphology with the same model. The curvature effect is also taken into account perturbatively in our analysis. We then find that the gyroid morphology may appear near the transition point from a cylinder to a slab as well as that from a slab to a cylindrical hole. This interesting analogy between nuclear and polymer systems is not merely qualitative. The volume fraction at the phase transition is also similar for the two systems. Our results are also interesting because recent studies on the dynamics of pasta phases by quantum molecular dynamics show that intermediate phases, which are different from any of the known pasta phases, may emerge between the cylinder and slab phases as well as between the slab and cylindrical holes phases.
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