Curvature-Activated Majorana Condensate in Palatini Gravity: A Minimal EFT Framework for Inflation without an Inflaton

Inflation without an inflaton from a curvature-activated sterile Majorana condensate in Palatini f(R)f(\mathcal{R})f(R) gravity. This record contains the LaTeX source and PDF of a model-definition manuscript where an NJL-like sterile Majorana sector undergoes a curvature-controlled transition into (and out of) a condensed phase that provides a metastable vacuum energy driving an early accelerated expansion. Gravity is treated in Palatini f(R)f(\mathcal{R})f(R), so the Palatini scalar R\mathcal{R}R is eliminated algebraically, while the matter EFT and heat-kernel expansion are formulated in terms of the metric curvature R(g)R(g)R(g). Key elements Clear separation of R\mathcal{R}R, R(h)R(h)R(h), and R(g)R(g)R(g) and controlled use of the conformal relation (slow-variation regime). Curvature-dependent four-fermion coupling Geff(R(g))\,G_{\rm eff}(R(g))Geff(R(g)) and operational definition of the critical coupling GcG_cGc using a proper-time UV cutoff (with scheme-dependence remarks). Bosonized effective potential, gap condition, and a closed coupled algebraic background system (gap + Palatini trace), plus EFT control conditions and a posteriori consistency checks. Technical roadmap for perturbations/observables and for exit/reheating analyses (left for follow-up work). License: CC BY 4.0 (see record metadata). Keywords: Palatini gravity; f(R)f(R)f(R); Majorana fermions; NJL; fermion condensate; curvature activation; heat-kernel; early Universe inflation; effective field theory