  The Large Hadron Collider (LHC) at CERN houses two general purpose detectors
- ATLAS and CMS - which conduct physics programs over multi-year runs to
generate increasingly precise and extensive datasets. The efforts of the CMS
and ATLAS collaborations lead to the discovery of the Higgs boson, a
fundamental particle that gives mass to other particles, representing a
monumental achievement in the field of particle physics that was recognized
with the awarding of the Nobel Prize in Physics in 2013 to Fran\c{c}ois Englert
and Peter Higgs. These collaborations continue to analyze data from the LHC and
are preparing for the high luminosity data taking phase at the end of the
decade. The computing models of these detectors rely on a distributed
processing grid hosted by more than 150 associated universities and
laboratories worldwide. However, such new data will require a significant
expansion of the existing computing infrastructure. To address this, both
collaborations have been working for years on integrating High Performance
Computers (HPC) and commercial cloud resources into their infrastructure and
continue to assess the potential role of such resources in order to cope with
the demands of the new high luminosity era. US ATLAS and US CMS computing
management have charged the authors to provide a blueprint document looking at
current and possibly future use of HPC and Cloud resources, outlining
integration models, possibilities, challenges and costs. The document will
address key questions such as the optimal use of resources for the experiments
and funding agencies, the main obstacles that need to be overcome for resource
adoption, and areas that require more attention.
