Cut time (also called "alla breve") in music notation is represented by a stylized 'C' with a vertical line through it where the time signature would normally be. It represents 2/2 time, and is so called because it is equivalent to common time but "cut in half".
It looks something like this:
/\
|----| /-------
| |/
|----/------|--
| /| /|\
|--/-|/\--|-|--
| | | | \|/
|-| -|--|---|--
| \ | |
|---\|_/-------
|
\|
| 
