あるかないか

expression

whether or not; ... or lack thereof

Used to express uncertainty about existence or occurrence, often in the pattern ～かどうか or as a noun modifier.

• 彼かれが来くるかどうかは、あるかないか分わからない。

  I don't know whether he will come or not.

• その情じょう報ほうの真しん偽ぎはあるかないかのレベルだ。

  The truth of that information is at the level of whether it even exists or not.

expression, noun which may take the genitive case particle 'no'

faint hint of; barely there

Describes something so slight that its existence is questionable. Often used attributively with の.

• 彼かれの顔かおにはあるかないかの笑えみが浮うかんでいた。

  A faint hint of a smile appeared on his face.

• その差さはあるかないか程てい度どのものだ。

  The difference is so slight it's barely there.