  The Large Hadron Collider presents an unprecedented opportunity to probe the
realm of new physics in the TeV region and shed light on some of the core
unresolved issues of particle physics. These include the nature of electroweak
symmetry breaking, the origin of mass, the possible constituent of cold dark
matter, new sources of CP violation needed to explain the baryon excess in the
universe, the possible existence of extra gauge groups and extra matter, and
importantly the path Nature chooses to resolve the hierarchy problem - is it
supersymmetry or extra dimensions. Many models of new physics beyond the
standard model contain a hidden sector which can be probed at the LHC.
Additionally, the LHC will be a top factory and accurate measurements of the
properties of the top and its rare decays will provide a window to new physics.
Further, the LHC could shed light on the origin of neutralino masses if the new
physics associated with their generation lies in the TeV region. Finally, the
LHC is also a laboratory to test the hypothesis of TeV scale strings and
D-brane models. An overview of these possibilities is presented in the spirit
that it will serve as a companion to the Technical Design Reports (TDRs) by the
particle detector groups ATLAS and CMS to facilitate the test of the new
theoretical ideas at the LHC. Which of these ideas stands the test of the LHC
data will govern the course of particle physics in the subsequent decades.
