Advanced Event Ticketing Dynamic Pricing Engine

Build a sophisticated dynamic pricing algorithm for an event ticketing platform using Laravel, incorporating machine learning predictive models to optimize ticket pricing in real-time. Develop a system that considers factors like historical demand, artist popularity, venue capacity, time until event, and current market trends. Create a robust caching mechanism using Redis to handle high-concurrency pricing calculations, and implement a background job that continuously refines pricing models based on sales data.