  This document provides input from the CLIC e+e- linear collider studies to
the update process of the European Strategy for Particle Physics. It is
submitted on behalf of the CLIC/CTF3 collaboration and the CLIC physics and
detector study. It describes the exploration of fundamental questions in
particle physics at the energy frontier with a future TeV-scale e+e- linear
collider based on the Compact Linear Collider (CLIC) two-beam acceleration
technique. A high-luminosity high-energy e+e- collider allows for the
exploration of Standard Model physics, such as precise measurements of the
Higgs, top and gauge sectors, as well as for a multitude of searches for New
Physics, either through direct discovery or indirectly, via high-precision
observables. Given the current state of knowledge, following the observation of
a \sim125 GeV Higgs-like particle at the LHC, and pending further LHC results
at 8 TeV and 14 TeV, a linear e+e- collider built and operated in
centre-of-mass energy stages from a few-hundred GeV up to a few TeV will be an
ideal physics exploration tool, complementing the LHC. Two example scenarios
are presented for a CLIC accelerator built in three main stages of 500 GeV, 1.4
(1.5) TeV, and 3 TeV, together with the layout and performance of the
experiments and accompanied by cost estimates. The resulting CLIC physics
potential and measurement precisions are illustrated through detector
simulations under realistic beam conditions.
