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Commit e27fca48 authored by Luke Naylor's avatar Luke Naylor
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Introduce twisted Chern and associated condition

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......@@ -12,6 +12,7 @@
\newcommand{\chern}{\operatorname{ch}}
\newcommand{\firsttilt}[1]{\mathcal{B}^{#1}}
\newcommand{\bddderived}{\mathcal{D}^{b}}
\newcommand{\centralcharge}{\mathcal{Z}}
\begin{document}
......@@ -67,9 +68,39 @@ used, followed by refinements on them which give explicit formulae for tighter
bounds on $\chern_0(E)$ of potential destabilizers $E$ of $F$.
\section{Section 1}
\section{Characteristic Curves of Stability Conditions Associated to Chern
Characters}
\section{Section 2}
\section{Twisted Chern Characters of Pseudo Destabilizers}
For a given $\beta$, we can define a twisted Chern character
$\chern^\beta(E) = \chern(E) \cdot \exp(-\beta \ell)$:
\begin{align*}
\chern^\beta_0(E) &= \chern_0(E)
\\
\chern^\beta_1(E) &= \chern_1(E) - \beta \chern_0(E)
\\
\chern^\beta_2(E) &= \chern_2(E) - \beta \chern_1(E) + \frac{\beta^2}{2} \chern_0(E)
\end{align*}
$\chern^\beta_1(E)$ is the imaginary component of the central charge
$\centralcharge_{\alpha,\beta}(E)$ and any element of $\firsttilt\beta$
satisfies $\chern^\beta_1 \geq 0$. This, along with additivity gives us, for any
destabilizing sequence [ref]:
\[
0 \leq \chern^\beta_1(E) \leq \chern^\beta_1(F)
\]
When finding Chern characters of potential destabilizers $E$ for some fixed
Chern character $\chern(F)$, this bounds $\chern_1(E)$.
The Bogomolov form applied to the twisted Chern character is the same as the
normal one. So $0 \leq \Delta(E)$ yields:
\[
\chern^\beta_0 \chern^\beta_2 \leq \left(\chern^\beta_1\right)^2
\]
\section{Section 3}
......
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