A subsequent question of this one. When the Clone Army arrives at Geonosis, why didn't they capture the Sith Lord and the Separatist Leaders? They had the advantage, because they almost destroyed the Droid Army.
They could not. Advantage of Clone Army was not so great, it was very hard battle, leading to second battle some time after that. Note that Clone army throughout the war rarely had numerical superiority over Droids. They would usually had to destroy large number of enemies before achieving strategic goal. In this case there were simply no time to protect Jedi in Arena, battle droids and capture leadership. Especially hard would be to capture powerful Sith Lord like Dooku when even Yoda could not do that.