The negative-curve characterization of instability for line bundles

From papers

Let XX be a smooth complex projective surface, let B,ω\biginNS(X)RB,\omega\bigin\operatorname{NS}(X)\otimes\mathbb{R} with ω\omega ample, and let σB,ω=(ZB,ω,AB,ω)\sigma_{B,\omega}=(Z_{B,\omega},\mathscr{A}_{B,\omega}) be the Bridgeland stability condition defined by the tilted heart and central charge above. For a line bundle LL on XX, write L(C)CL(C)|_C for the restriction to CC of L(C)L(C). Negative-curve instability conjecture. (a) If LAB,ωL\in\mathscr{A}_{B,\omega}, then LL is not σB,ω\sigma_{B,\omega}-stable if and only if there exists a curve CC of negative self-intersection such that L(C)L(-C) is a subobject of LL in AB,ω\mathscr{A}_{B,\omega} and

0<ArgZB,ω(L)ArgZB,ω(L(C))π.0<\operatorname{Arg} Z_{B,\omega}(L)\leq\operatorname{Arg} Z_{B,\omega}(L(-C))\leq\pi.

(b) If L[1]AB,ωL[1]\in\mathscr{A}_{B,\omega}, then LL is not σB,ω\sigma_{B,\omega}-stable if and only if there exists a curve CC of negative self-intersection such that L(C)CL(C)|_C is a subobject of L[1]L[1] in AB,ω\mathscr{A}_{B,\omega} and

0<ArgZB,ω(L[1])ArgZB,ω(L(C)C)π.0<\operatorname{Arg} Z_{B,\omega}(L[1])\leq\operatorname{Arg} Z_{B,\omega}(L(C)|_C)\leq\pi.

This conjecture aims to characterize precisely the mechanisms by which a line bundle can fail to be Bridgeland stable: instability should arise exactly from subobjects associated with curves of negative self-intersection. Its status is unresolved in the supplied source.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Yu-Wei Fan, “Notes on the deformed Hermitian-Yang-Mills equations and the large scaling limits of stability conditions”, arXiv:2604.22246 (2026).

Solutions 0

No solutions have been posted yet.