Sections of symmetric powers of the tangent bundle

Establish whether every Fano manifold of Picard number one admitting a non-isomorphic surjective endomorphism has a positive integer $m$ for which $H^0(X,\operatorname{Sym}^m T_X)\neq 0$, and determine whether its tangent bundle is big.

Background

The paper notes a folklore conjecture that a Fano manifold of Picard number one admitting a non-isomorphic surjective endomorphism should be projective space. Existing results had only partially addressed this expectation under the stronger assumption that the tautological line bundle on the projectivized tangent bundle is big.

The authors propose a related conjecture implied by stronger positivity of the tangent bundle: the existence of nonzero sections in some symmetric power of the tangent bundle, with the more optimistic possibility that the tangent bundle itself is big.

References

It is a folklore conjecture that a Fano manifold of Picard number one admitting a non-isomorphic surjective endomorphism is isomorphic to projective space. The conjecture was partially solved in under the assumption that $\mathcal{O}_{\mathbb{P}(T_X)}(1)$ is big. Building on this result, Theorem \ref{t:pos} may be viewed as a first step toward the following expectation.

\begin{conjecture}[{cf.~Remark \ref{r:pos-cur} (3)}]\label{Conj-big} Let $X$ be a Fano manifold of Picard number one admitting a non-isomorphic surjective endomorphism. Then there is a positive integer $m$ such that $H0(X,SymmT_X)\neq 0$. More optimistically, the tangent bundle $T_X$ is big. \end{conjecture}

Positivity of compact Kähler varieties admitting an int-amplified endomorphism  (2609.09869 - Matsumura et al., 9 Sep 2026) in Conjecture 1.8, Subsection 1.2, following Corollary 1.7