The particle beams are heavy hitters, but fire so slowly. Smaller beams with lower strength but faster reload would threaten beam fighters more effectively at a medium range.
The Centauri are paying for their tactical mistakes and overconfidence, but now with a larger fleet en route may have learned their lessons. I think Earth can still win this engagement, and even if the cost is heavy in ships and lives the strategic gains from a victory here will outweigh those losses in the longer term, as the Centauri will be effectively out of the picture as a future threat. Retreating now means committing to a costly jump point assault later on unless the Centauri are truly reckless enough to follow the Earth ships through.
In the long term Earth is potentially a bit screwed, as regardless of the final result here having an active enemy threat so close to Sol will cost many resources that cannot be leveraged against any other threats that materialize - whether those resources are destroyed in action or tied to the defense of a jump point. At least eliminating the Centauri will allow any surviving ships, however damaged, to be repaired and redeployed, hopefully before a new threat materializes.
