Align equations in enumerate environment

Question

I want to left align equations just as the items in the left.

I used the following code but it only align items not equations

\begin{enumerate}[align=left]
\item[Charm] $C\equiv N_c\equiv N(c)-N(\bar{c})$
\item[Strangeness] $S\equiv -N_s\equiv -[N(s)-N(\bar{s})]$
\item[Bottomness] $\tilde{B}\equiv N_b\equiv -[N(b)-N(\bar{b})]$
\item[Topness] $T\equiv N_t\equiv N(t)-N(\bar{t})$
\end{enumerate}

Answer 1

Not precisely what the O.P. requested, but I suggest to use an alignat environment rather.

\documentclass{article}

\usepackage{mathtools}
\begin{document}

\begin{alignat}{4}
&\text{Charmness}   &\quad &  C          &\quad\equiv  \phantom{-}N_{c}  &\equiv \quad \phantom{-[} N(c)-N(\bar{c})\phantom{]} \\
&\text{Strangeness} &\quad &  S          &\quad\equiv   -N_s             &\equiv \quad -[N(s)-N(\bar{s})] \\
&\text{Bottomness}  &\quad &  \widetilde{B}  &\quad\equiv  \phantom{-}  N_b  &\equiv \quad -[N(b)-N(\bar{b})] \\
&\text{Topness}     &\quad &  T          &\quad\equiv  \phantom{-}  N_t  &\equiv \quad \phantom{-[} N(t)-N(\bar{t})\phantom{]}  
\end{alignat}


\begin{alignat*}{4}
&\text{Charmness}   &\quad &  C          &\quad\equiv  \phantom{-}N_{c}  &\equiv \quad \phantom{-[} N(c)-N(\bar{c})\phantom{]} \\
&\text{Strangeness} &\quad &  S          &\quad\equiv   -N_s             &\equiv \quad -[N(s)-N(\bar{s})] \\
&\text{Bottomness}  &\quad &  \widetilde{B}  &\quad\equiv  \phantom{-}  N_b  &\equiv \quad -[N(b)-N(\bar{b})] \\
&\text{Topness}     &\quad &  T          &\quad\equiv  \phantom{-}  N_t  &\equiv \quad \phantom{-[} N(t)-N(\bar{t})\phantom{]}  
\end{alignat*}


\end{document}

Answer 2

I doubt too that a list is the correct environment, but if some reason you really want it, I would do it like this:

\documentclass{article}

\usepackage{enumitem,calc}
\begin{document}
\begin{description}[font=\normalfont,labelwidth=\widthof{Strangeness~},leftmargin=!]
\item[Charm] $C\equiv N_c\equiv N(c)-N(\bar{c})$
\item[Strangeness] $S\equiv -N_s\equiv -[N(s)-N(\bar{s})]$
\item[Bottomness] $\tilde{B}\equiv N_b\equiv -[N(b)-N(\bar{b})]$
\item[Topness] $T\equiv N_t\equiv N(t)-N(\bar{t})$
\end{description}
\end{document}

Answer 3

I was about to post this other possibility

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{enumitem}

\begin{document}

\begin{enumerate}[align=left, leftmargin=*, widest=Strangeness]
\item[Charm] $C\equiv N_c\equiv N(c)-N(\bar{c})$
\item[Strangeness] $S\equiv -N_s\equiv -[N(s)-N(\bar{s})]$
\item[Bottomness] $\tilde{B}\equiv N_b\equiv -[N(b)-N(\bar{b})]$
\item[Topness] $T\equiv N_t\equiv N(t)-N(\bar{t})$
\end{enumerate}

\end{document}

when Ulrike Fischer posted her answer. But maybe it is still of interest.

Here is the output: is actually “strangeness” the widest label? (This question shows a drawback of this method.)

Answer 4

With a two-pass approach one can avoid guessing at the widest label:

\documentclass{article}
\usepackage{enumitem}
\usepackage{lipsum}

\newcounter{tabdesc}
\newlength\tabdescwd
\newenvironment{tabdesc}
 {\setlength{\tabdescwd}{0pt}\stepcounter{tabdesc}\let\item\tabdescitem
  \description[labelwidth=\thistabdescwd,font=\normalfont,leftmargin=!]}
 {\writethistabdescwd\enddescription}

\makeatletter
\let\saved@item\item
\def\tabdescitem[#1]{%
  \sbox\z@{\normalfont #1}%
  \ifdim\wd\z@>\tabdescwd\setlength{\tabdescwd}{\wd\z@}\fi
  \saved@item[#1]%
}
\def\writethistabdescwd{%
  \immediate\write\@auxout{%
    \gdef
    \expandafter\string\csname tabdesc@\romannumeral\value{tabdesc}\endcsname
    {\the\tabdescwd}%
  }%
}
\def\thistabdescwd{%
  \@ifundefined{tabdesc@\romannumeral\value{tabdesc}}{4em}{%
    \csname tabdesc@\romannumeral\value{tabdesc}\endcsname}%
}
\makeatother

\begin{document}

\lipsum*[2]
\begin{tabdesc}
\item[Charm] $C\equiv N_c\equiv N(c)-N(\bar{c})$
\item[Strangeness] $S\equiv -N_s\equiv -[N(s)-N(\bar{s})]$
\item[Bottomness] $\tilde{B}\equiv N_b\equiv -[N(b)-N(\bar{b})]$
\item[Topness] $T\equiv N_t\equiv N(t)-N(\bar{t})$
\end{tabdesc}
\lipsum[3]

\end{document}

I wouldn't try and aligning all the \equiv symbols.

Answer 5

A very simple solution with enumitem:

\documentclass{article}

\usepackage{enumitem}
\usepackage[showframe]{geometry}

\begin{document}

\begin{enumerate}[wide=0pt, widest=Strangeness, leftmargin=*]
  \item[Charm] $C\equiv N_c\equiv N(c)-N(\bar{c})$
  \item[Strangeness] $S\equiv -N_s\equiv -[N(s)-N(\bar{s})]$
  \item[Bottomness] $\tilde{B}\equiv N_b\equiv -[N(b)-N(\bar{b})]$
  \item[Topness] $T\equiv N_t\equiv N(t)-N(\bar{t})$
\end{enumerate}
\vskip1cm

\begin{enumerate}[wide, widest=Strangeness, leftmargin=*]
  \item[Charm] $C\equiv N_c\equiv N(c)-N(\bar{c})$
  \item[Strangeness] $S\equiv -N_s\equiv -[N(s)-N(\bar{s})]$
  \item[Bottomness] $\tilde{B}\equiv N_b\equiv -[N(b)-N(\bar{b})]$
  \item[Topness] $T\equiv N_t\equiv N(t)-N(\bar{t})$
\end{enumerate}

\end{document}