Performance and strategies of the b,-jet selection for the ATLAS High-Level Trigger

The challenging environment in which the ATLAS detector is going to operate implies a sophisticated trigger strategy. The online b-jet selection is thus an important ingredient which greatly improves the trigger flexibility and extend the ATLAS physics programme. In particular, b-jets acceptance is increased and the backgroung reduced by lowering jet transverse energy thresholds at the first trigger level and then applying online b-tagging. Different physics channels, especially topologies containing more than one b-jet where higher rejection factors are achieved, benefit from requesting this kind of trigger to be fired. We present an overview of the status-of-the-art of the b-jet trigger menu at the experiment start-up.