Barron Hilton Puncher -- Arrest Imminent

The man who socked out Paris Hilton's little bro WILL BE arrested for the attack ... law enforcement sources tell TMZ.

We broke the story ... Lindsay Lohan's friend Ray LeMoine has admitted he threw the punches that wrecked Barron Hilton's face during a mansion party in Miami last week -- though Ray claims Barron struck him first.

Still, law enforcement sources tell TMZ ... officials now believe they have "probable cause" to arrest Ray and will most likely make their move in the very near future.

Barron Hilton claims Lindsay orchestrated the attack because she thought he was talking smack about her at the party. LeMoine claims LL had nothing to do with the altercation.

Barron not only wants to press charges -- we're told he wants to sue both Lindsay and Ray.