PID Performance in the LHCb High Level Trigger

The LHCb High Level Trigger (HLT) incorporates RICH particle identification (PID) calculations that are designed to be faster than those used for the offline reconstruction, which is necessary due to the timing constraints imposed on the HLT. The performance of this faster calculation has been evaluated using $B^+ \to \overline{D}^0\pi^+$ events recorded during 2011 data taking and compared against the performance of the offline calculation. The time taken to calculate PID information in the HLT has been measured both for the configuration used in Run 1, and for configurations approaching that used offline. Similar overall efficiency and misidentification performance is seen in the configurations used offline and in the HLT, though the raw values of PID variables can differ substantially for a given candidate.