Contraction with hat

[alejandrogallo]

Hi!

For some reason this does not work

  \wick{
    \c \hat{a} \c \hat{b}
  }

Cheers!

[schtandard]

Well, \c is a macro that eventually absorbs an argument; in your case \hat. As always in LaTeX, you need to add braces in order for the syntax not to break:

\wick{
  \c {\hat{a}} \c {\hat{b}}
}

(You will want to modify some parameters to account for the additional height of the characters.)