使用箭头或其他包来连接不同位置的方程式

Question

本 MWE，

\documentclass[a4paper,12pt]{article}
\usepackage{newtxtext,newtxmath,amssymb}
\usepackage{mathrsfs}
\usepackage{xcolor}
\usepackage[most]{tcolorbox}
\newtcolorbox{mybox}[1]{%
    colback=teal!10,
    coltitle=black,
    colframe=teal!30,
    fonttitle=\bfseries,
    title=#1, 
    sharp corners,
    boxrule=0pt,
    enhanced}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}    
\usepackage{lipsum}

\begin{document}
\[
\mathscr{L}(\Psi(\bar{r},t))=\iiiint_{\mathbb{R}^{4}}\mathscr{L}\left(G(\bar{r},\bar{r}',t,t') f(\bar{r}',t')\right) dx'dy'dz'dt'=(\star)
\]
\lipsum[1]
\begin{mybox}{}
\begin{equation}
\begin{aligned}
(\star)&= \iiiint_{\mathbb{R}^{4}}\left(\mathscr{L}(G (\bar{r},\bar{r}',t,t')\right) f(\bar{r}',t') \,dx'dy'dz'dt'=\\
&= \iiiint_{\mathbb{R}^{4}}\left(-4\pi \delta(\bar{r} -\bar{r}')\delta(t -t'))\right) f(\bar{r}',t') \,dx'dy'dz'dt'=\\
&= -4\pi \iiiint_{\mathbb{R}^{4}}\delta(\bar{r} -\bar{r}')\delta(t -t') f(\bar{r}',t') \,dx'dy'dz'dt'=\\
&=-4\pi f(\bar{r},t)
\end{aligned}
\end{equation}
\end{mybox}
\end{document}

产生以下输出：

我的问题很简单：有没有另一种优雅的方式来连接两个方程式，用文字隔开，我使用的是符号\star？我曾想过这样的东西（witharrows包），

但它不会侵入顶部两个方程式之间的文本以及底部的彩色框。

欢迎提出任何更好的建议（并更改我的标签）。

Answer 1

\documentclass[a4paper,12pt]{article}
\usepackage{newtxtext,newtxmath,amssymb}
\usepackage{mathrsfs}
\usepackage{xcolor}
\usepackage[most]{tcolorbox}
\newtcolorbox{mybox}[1]{%
    colback=teal!10,
    coltitle=black,
    colframe=teal!30,
    fonttitle=\bfseries,
    title=#1, 
    sharp corners,
    boxrule=0pt,
    enhanced}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}    
\usepackage{lipsum}
\usepackage{tikz} 
\usetikzlibrary{tikzmark,calc}


\begin{document}
\[
\mathscr{L}(\Psi(\bar{r},t))=\iiiint_{\mathbb{R}^{4}}\mathscr{L}\left(G(\bar{r},\bar{r}',t,t') f(\bar{r}',t')\right) dx'dy'dz'dt'=\tikzmark{start}
\]
\lipsum[1]
\begin{mybox}{}
\begin{equation}
\begin{aligned}
\tikzmark{stop}&= \iiiint_{\mathbb{R}^{4}}\left(\mathscr{L}(G (\bar{r},\bar{r}',t,t')\right) f(\bar{r}',t') \,dx'dy'dz'dt'=\\
&= \iiiint_{\mathbb{R}^{4}}\left(-4\pi \delta(\bar{r} -\bar{r}')\delta(t -t'))\right) f(\bar{r}',t') \,dx'dy'dz'dt'=\\
&= -4\pi \iiiint_{\mathbb{R}^{4}}\delta(\bar{r} -\bar{r}')\delta(t -t') f(\bar{r}',t') \,dx'dy'dz'dt'=\\
&=-4\pi f(\bar{r},t)
\end{aligned}
\end{equation}
\end{mybox}
\begin{tikzpicture}[remember picture, overlay]
\draw[->] (pic cs:start) -- ++(0,-0.5) -- ++(-13,0) |- (pic cs:stop);
\end{tikzpicture}
\end{document}

Answer 2

就我个人而言，我更喜欢将方程的名称重写为解释性文本的逻辑结果。并以因此我们有：

在我看来，如果箭头和其他装饰物的优点是可以起到漂亮的装饰作用，那么它们并不能使演示更加明确或更容易理解。

\documentclass[a4paper,12pt]{article}
\usepackage{newtxtext,newtxmath,amssymb}
\usepackage{mathrsfs}
\usepackage{xcolor}
\usepackage[most]{tcolorbox}
\newtcolorbox{mybox}[1]{%
    colback=teal!10,
    coltitle=black,
    colframe=teal!30,
    fonttitle=\bfseries,
    title=#1, 
    sharp corners,
    boxrule=0pt,
    enhanced}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}    
\usepackage{lipsum}

\begin{document}
\[
\mathscr{L}(\Psi(\bar{r},t))=\iiiint_{\mathbb{R}^{4}}\mathscr{L}\left(G(\bar{r},\bar{r}',t,t') f(\bar{r}',t')\right) dx'dy'dz'dt'
\]
\lipsum[1]


\begin{mybox}{}
And so we have:
\begin{equation}
\begin{aligned}
\mathscr{L}(\Psi(\bar{r},t))&=  \iiiint_{\mathbb{R}^{4}}\left(-4\pi \delta(\bar{r} -\bar{r}')\delta(t -t'))\right) f(\bar{r}',t') \,dx'dy'dz'dt'=\\
&= -4\pi \iiiint_{\mathbb{R}^{4}}\delta(\bar{r} -\bar{r}')\delta(t -t') f(\bar{r}',t') \,dx'dy'dz'dt'=\\
&=-4\pi f(\bar{r},t)
\end{aligned}
\end{equation}
\end{mybox}
\end{document}