Can paypal reverse withdraw or take money from my bank account without my permission?

Hello,
I was recently scammed by someone. I had sold him bitcoins for $1100 through PayPal transaction and a few days later he claimed a dispute in PayPal for unauthorized transaction.
Now PayPal has ruled their decision in favor of him and I need to pay back the amount. I don't have the balance in my PayPal account as i had withdrawn it out earlier to my bank account and since there is a negative balance in my account, I cant perform any PayPal transaction.
That is a lot off money to pay and since I kept my side of the bargain, I don't want to pay that money.
My question is in case i do not pay back the money to PayPal, will they be able to reverse the withdraw or charge out of my bank account? (i do not have any CC linked but have a debit card linked to PayPal).

Note: I have received an email stating
PayPal has made a transfer between the balances in your account due to the following reason:
Our policy of converting negative to positive balances.

What does that mean?

 

That is their policy so they will collect the money and if you cancel the DD go after you via legal means.

 

If you have balance in your Debit card thats linked they will cut the amount that they have paid against your payment.
As stated above it seems paypal has paid for you to the customer due to negative balance. Once you get payment in your paypal account they will start cutting the amount the owe.

 

I doubt they can, i know in UK if you set up direct debit with payment processor they can leech money from your account.