The ATLAS Transverse Momentum Trigger at the LHC

The transverse momentum triggers of the ATLAS experiment at the CERN Large Hadron Collider (LHC) are designed to select collision events with non-interacting particles passing through the detector. Such events provide an interesting probe for new-physics interactions beyond the Standard Model, and also provide the basis for precise measurements of Standard Model parameters such as Higgs couplings. The transverse momentum used in the trigger system is calculated from calorimeter- based global energy sums and supplemented with information from the muon detection system. The trigger successfully operated during the first running period of the LHC. Starting in 2015 the LHC will produce collisions at higher energy and increased luminosity; improving on the trigger performance from the previous run period will be challenging.