Theorem 10.20.1.C4F23D785797 Let $\mu $ be a smooth positive volume form with $\mu (X)=\operatorname {vol}(\alpha )$. The normalized full-mass solution $\varphi \in \mathcal E(X,\theta )$ of
6DBC0A4AFE96
10.20.2
\begin{equation} \bigl \langle (\theta +\mathrm{dd}^{\mathrm{c}}\varphi )^ n\bigr \rangle =\mu , \qquad \sup _ X\varphi =0, \end{equation}
is smooth on $\operatorname {Amp}(\alpha )$, and the restriction of $\theta +\mathrm{dd}^{\mathrm{c}}\varphi $ to this locus is a Kähler form.
Proof.
Fix a Kähler form $\omega $ and put $f=\mu /\omega ^ n$. Since $X$ is compact and $\mu $ is smooth, $f\in L^ p(X,\omega ^ n)$ for every finite $p>1$. The classical estimate for this equation, discussed in section 25.21, shows that $\varphi $ has minimal singularities: there is a constant $C>0$ such that
658C9DBC52ED
10.20.3
\begin{equation} V_\theta -C\leq \varphi \leq V_\theta . \end{equation}
The upper bound follows from the normalization.
Let $T=\theta +\mathrm{dd}^{\mathrm{c}}\rho $ be a Kähler current with analytic singularities as in theorem 10.13.2. Its potential $\rho $ has analytic singularities with smooth remainder, and for some constant $\varepsilon >0$,
\[ T=\theta +\mathrm{dd}^{\mathrm{c}}\rho \geq \varepsilon \omega , \qquad \{ \rho =-\infty \} =E_{\mathrm{nK}}(\alpha ). \]
Thus $\rho $ is smooth on $\Omega =\operatorname {Amp}(\alpha )$. After subtracting a constant we may assume $\rho \leq 0$, hence $\rho \leq V_\theta $, and (10.20.3) gives
\[ \rho -C\leq \varphi \leq 0. \]
In particular $\varphi $ is locally bounded on $\Omega $, and by locality its non-pluripolar equation there is the equation for bounded potentials. The density $f$ belongs to $L^ p$ on $X$ and is smooth and strictly positive on $\Omega $. Hence all hypotheses of corollary 15.18.50 hold for the strict barrier $\rho $, so $\varphi $ is smooth and $\theta +\mathrm{dd}^{\mathrm{c}}\varphi >0$ on $\Omega $. Since $\theta $ is closed, this form is Kähler.
$\square$
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