# Textbook definition a c-number

1. Sep 6, 2005

### fliptomato

Hello everyone--I was hoping someone could give (or refer to) a textbook definition of a $$c$$-number, as used in the context of quantum field theory.

Does this refer to a commuting number? I've also read it referring to a classical quantity. classical quantity, from a not-very-reputable source. (Though are these the same?)

If the 'c' refers to commuting, when I read something like "...spinors are anti-commuting (c-numbers)." (Bailin and Love, SUSY book) Does this mean that spinors are anti-commuting objects composed of commuting numbers? (It certainly doesn't mean that the spinors themselves are commuting...)

Thanks,
Flip

2. Sep 6, 2005

### Norman

C-number usually refers to "complex" number. At least that is all I have ever seen it used as.

3. Sep 6, 2005

4. Sep 8, 2005

### snooper007

c-number is really defined as a classical number. it is not an operator or
spinor.!

anticommuting number is Grassmann number used in the functional integral
representation of fermionic field.

Often the Grassman number is not called c-number, maybe someone can call
Grassmann number as c-number.