The stability for F-Yang-Mills functional on CP^n
Yang Wen
TL;DR
The paper addresses stability of the $F$-Yang-Mills functional on complex projective space $\mathbb{C}P^n$ and characterizes when weakly stable connections must be flat or have rigid curvature form. It develops a second-variation framework for $\mathscr{A}_F(\nabla)=\int F(\tfrac12|R^\nabla|^2)$, and analyzes it via Killing-vector-field variations on $\mathbb{C}P^n$, leveraging the Bochner-Weitzenböck identity. The main results show that a negativity condition on $F''$ and $F'$ forces stability to imply trivial curvature, while equality yields a precise curvature structure $R^\nabla(X,Y)=g(X,JY)\,\sigma$, along with a gap theorem bounding $\|R^\nabla\|_{L^\infty}$ to force flatness. Together, these findings clarify stability and curvature constraints for generalized Yang–Mills functionals on symmetric spaces, with explicit corollaries for power-type $F$ on low-dimensional projective spaces.
Abstract
In this paper, we study the critical points of $F$-Yang-Mills functional on $\mathbb{C}P^n$, which are called $F$-Yang-Mills connections. We prove that if $(2+\frac4n)F''(x)x+(n+1)F'(x)<0$, then the weakly stable $F$-Yang-Mills connection on $\mathbb{C}P^n$ must be flat. Moreover, if $(2+\frac4n)F''(x)x+(n+1)F'(x)=0$, we obtain the structure of curvatures corresponding to weakly stable connections. We also show a gap theorem for $F$-Yang-Mills connections on $\mathbb{C}P^n$.
