\( \def\CC{{\mathbb C}} \def\RR{{\mathbb R}} \def\NN{{\mathbb N}} \def\ZZ{{\mathbb Z}} \def\QQ{{\mathbb Q}} \def\TT{{\mathbb T}} \def\CF{{\operatorname{CF}^\bullet}} \def\HF{{\operatorname{HF}^\bullet}} \def\SH{{\operatorname{SH}^\bullet}} \def\ot{{\leftarrow}} \def\st{\;:\;} \def\Fuk{{\operatorname{Fuk}}} \def\emprod{m} \def\cone{\operatorname{Cone}} \def\Flux{\operatorname{Flux}} \def\li{i} \def\ev{\operatorname{ev}} \def\id{\operatorname{id}} \def\grad{\operatorname{grad}} \def\ind{\operatorname{ind}} \def\weight{\operatorname{wt}} \def\Sym{\operatorname{Sym}} \def\HeF{\widehat{CHF}^\bullet} \def\HHeF{\widehat{HHF}^\bullet} \def\Spinc{\operatorname{Spin}^c} \def\min{\operatorname{min}} \def\div{\operatorname{div}} \def\SH{{\operatorname{SH}^\bullet}} \def\CF{{\operatorname{CF}^\bullet}} \def\Tw{{\operatorname{Tw}}} \def\Log{{\operatorname{Log}}} \def\TropB{{\operatorname{TropB}}} \def\wt{{\operatorname{wt}}} \def\Span{{\operatorname{span}}} \def\Crit{\operatorname{Crit}} \def\CritVal{\operatorname{CritVal}} \def\FS{\operatorname{FS}} \def\Sing{\operatorname{Sing}} \def\Coh{\operatorname{Coh}} \def\Vect{\operatorname{Vect}} \def\into{\hookrightarrow} \def\tensor{\otimes} \def\CP{\mathbb{CP}} \def\eps{\varepsilon} \)

Symplectic snippets

special Lagrangian torus fibration

definition 0.0.1 [Mirror symmetry motivation notes]

Let \((X,\omega,\Omega)\) be a Calabi--Yau \(n\)-fold with its Ricci-flat Kähler metric, and assume that \(\Omega\) is normalized with respect to this metric. For \(\theta\in \RR/2\pi\ZZ\), an oriented real \(n\)-dimensional submanifold \(L\subset X\) is special Lagrangian of phase \(\theta\) if \[ \omega|_L=0,\qquad \operatorname{Im}(e^{-i\theta}\Omega)|_L=0, \] and \[ \operatorname{Re}(e^{-i\theta}\Omega)|_L=\operatorname{vol}_L \] as positive volume forms on \(L\). A special Lagrangian torus fibration of phase \(\theta\) is a continuous map \[ f:X\to B \] to a real \(n\)-dimensional base such that, over a dense open subset \(B_0\subset B\), the restriction \[ f^{-1}(B_0)\to B_0 \] is a smooth fiber bundle whose fibers are \(n\)-tori that are special Lagrangian submanifolds of phase \(\theta\). In the SYZ setting, nontrivial compact examples are expected to have singular fibers over a discriminant locus \(\Delta=B\setminus B_0\).

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