Overview

This package houses the code that runs as a first step of an xAOD slimming job. The code reads in an auxiliary store object of any type (implementing the SG::IAuxStore interface), and "wrapps" it into either an xAOD::AuxContainerBase or an xAOD::AuxInfoBase object.

Neither of these wrapper objects have any persistent variables of their own, they just report all variables of the wrapped object as dynamic variables, which Athena I/O then writes out into individual branches in the output file.

Algorithms

There is a single useful algorithm in the package at the moment, xAODMaker::AuxStoreWrapper. It can be configured to prepare just some selected, or all auxiliary store objects for slimming. Needs to be run as the first algorithm, before any of the auxiliary store objects would be read into StoreGate by some other algorithm.

Usage

After the algorithm is finished, the event store can no longer retrieve the auxiliary store objects as their original, specific type (e.g. xAOD::CaloClusterAuxContainer_v1), the event store will just hold proxies to generic xAOD::AuxContainerBase and xAOD::AuxInfoBase objects.

This means that while the output item list looks like the following after reconstruction:

StreamAOD.ItemList += [ "xAOD::CaloClusterContainer_v1#Clusters" ] StreamAOD.ItemList += [ "xAOD::CaloClusterAuxContainer_v1#ClustersAux." ]

, after running this algorithm, one needs to instead write something like:

StreamAOD.ItemList += [ "xAOD::CaloClusterContainer_v1#Clusters" ] StreamAOD.ItemList += [ "xAOD::AuxContainerBase#ClustersAux." ]

Adding the auxiliary variable selection at the end of the item string, following the latest formalism, now allows us to slim away variables which were read in as "static" variables.