Math & Science ⇒ Wide Bar in Math Mode

[Cham]

How can I tell LaTeX to put a wide bar on top of a symbol?

I need to write \Psi with a large bar, but \bar{\Psi} gives a too small bar on top. I need a large one (i.e. wide bar). Apparently, a command like \widebar doesn't exist, while \widetilde do exists.

For the ones familiar with quantum field theory, I need to write the "Dirac adjoint" of the bi-spinor field.

Any idea on this ?

[localghost]

Code: Select all

$\overline{\Psi}$

Thorsten

[Cham]

Code: Select all

$\overline{\Psi}$

Hmm, now I think that this bar is a bit too long. I'm not sure. I need to check how the Dirac adjoint is written elsewhere.


Edit:
OK, apparently, in most of the books I have, it's the usual \bar which appears to be used. However, most of them are using \psi instead of \Psi (I much prefer the latter), so I'm not sure yet how I should write the Dirac's adjoint.

[localghost]

[…] Hmm, now I think that this bar is a bit too long. I'm not sure. I need to check how the Dirac adjoint is written elsewhere. […]

No reason to despair. Define your own command if the given ones are not satisfactory.

Code: Select all

\documentclass[11pt]{article}

\newcommand*\xbar[1]{%
  \hbox{%
    \vbox{%
      \hrule height 0.5pt % The actual bar
      \kern0.5ex%         % Distance between bar and symbol
      \hbox{%
        \kern-0.1em%      % Shortening on the left side
        \ensuremath{#1}%
        \kern-0.1em%      % Shortening on the right side
      }%
    }%
  }%
} 

\begin{document}
  $\xbar{\Psi}$
\end{document}

The new command works both in text and mode.

[Cham]

Wow !

Your solution is pretty complex, but the result looks very nice.

I'll experiment with it.

Thanks a lot !

[samrob]

The package mathabx provides a \widebar macro. This is documented in "The Comprehensive LaTeX Symbol List".

For more disambiguation I thoroughly recommend to have a look at it.

[quatsch83]

No reason to despair. Define your own command if the given ones are not satisfactory.

This command doesn't work if used in a subscript. It doesn't change the size of the font to the proper subscript size.