Event selection and data analysis application. Project website.
DIRA: Direction angle
The angle between a line drawn from the primary vertex to the decay vertex of the particle and the sum of the 4-momentum of its decay products. One typically uses the cosine of the direction angle in selections.
DIRAC: Distributed Infrastructure with Remote Agent Control
DIRAC is the software framework for distributed computing used in LHCb. Official DIRAC website.
DOCA: Distance Of Closest Approach
The shortest distance between a pair of tracks.
DSS: Detector Safety System
Protection system for the experiment. Details in the Online System webpages.