You can override the onTabSelected to show/hide -
 @Override
public void onTabSelected(ActionBar.Tab tab,
        FragmentTransaction fragmentTransaction) {
    //get the tab position and show/hide 
    if (tab.getPosition() == 0) {
        ActionBar actionBar = getActionBar();
        actionBar.hide();
    } else {
        ActionBar actionBar = getActionBar();
        actionBar.show();
    }
}
UPDATE:
On onResume() method of each fragment you want to show your action bar -
@Override
public void onResume() {
    super.onResume();
    ActionBar actionBar = getActionBar();
    actionBar.show();
}
On onResume() method of each fragment you want to hide your action bar -
@Override
public void onResume() {
    super.onResume();
    ActionBar actionBar = getActionBar();
    actionBar.hide();
}