Legal Question in Real Estate Law in California

If a tenant does not pay rent within the three days of the three day pay or quit, the new owner can bring an unlawful detainer action to evict the tenant. I'm not sure what your exact question is.

Your question seems to suggest that the new owner/landlord is imposing tougher rental terms on an existing tenant, that the tenant has rejected the proposed new terms, had not paid, and has therefore been given a three-day notice. Without knowing whether this is fully correct or the timing and sequence of events, I can only guess what the answer is. However, please note that the tenant is probably entitled to 60 days' notice of a rent increase or other tightening of the rental conditions. Unless and until given 60 days notice, the prior rental terms remain in full force and effect. The tenant doesn't have to pay more -- but cannot refuse to pay the former rental.