deletions | additions       diff --git a/The VHE LHC.tex b/The VHE LHC.tex  index 26fcf5f..dbbc20f 100644  --- a/The VHE LHC.tex  +++ b/The VHE LHC.tex 
...
Precision measurements constitute only one facet of a sound high-energy-physics project for the future. They need to be complemented with direct searches for new phenomena at an energy-frontier facility, to possibly answer fundamental questions that will unavoidably arise from these precision measurements.   Both the $\epem$ Higgs factories discussed in Section~\ref{sec:Higgs} are accompanied by high-energy upgrade projects. For the ILC, it is foreseen to double its length to reach a centre-of-mass energy of 500 GeV, and it is not yet excluded to extend it by another factor of two towards $\sqrt{s} =$ 1 TeV. Another linear collider project, CLIC~\cite{cite:CLICDR}, could also take over for the high-energy physics programme all the way to $\sqrt{s}=$ 3 TeV. While it would also be possible, if it were justified by scientific reasons, to increase to centre-of-mass energy of TLEPall the way  to 500 GeV by tripling the RF length from 600 to 1700 m, the foreseen energy upgrade of TLEP is of another, unique, and more ambitious, nature. It would consist in re-using the 80-to-100 km tunnel for a very-large-energy large hadron collider (VHE-LHC). If instrumented with magnets of 16 T, pp collisions would be produced at a centre-of-mass energy of 80 to 100 TeV. Typically, $\epem$ colliders can pair-produce new particles with masses up to half the centre-of-mass energy, should they be either electrically charged or with a non-vanishing coupling to the Z. The reach of ILC500, ILC1000 and CLIC is therefore limited to particles lighter than 250, 500 and 1500 GeV/$c^2$, respectively. With the absence of new phenomena discovery at the LHC so far, air is therefore getting extremely thin for the ILC energy-frontier upgrade, even in its hypothetical 1-TeV version. The next LHC run at 13 TeV, expected to start in 2015, will bring the final word in this respect. A discovery of a new particle lighter than 1.5 TeV/$c^2$ in the 13-TeV LHC data would probably rejuvenate the proposal of CLIC at $\sqrt{s} =$ 3 TeV. Neutral particles with sizable direct coupling to fermions -- like new gauge bosons, for example -- can also be produced at $\epem$ colliders as $s$-channel resonances all the way to the highest centre-of-energy, but those are already excluded up to several TeV/$c^2$ by the LHC data at 8 TeV, and have therefore reduced interest in this context. A 100 TeV proton-proton collider would instead be able to produce new particles up to several tens of TeV/$c^2$, thus opening a unique window at high energy. A detailed study of the VHE-LHC physics case is therefore in order, and is foreseen to start at the beginning of 2014, in order to have relevant answers ready for the next European Strategy update in 2018.     Another facet of the physics programme of the energy-frontier projects is the direct measurement of the Higgs boson coupling to the top quark -- through ${\rm t\bar t H}$ production --, and the measurement of the Higgs trilinear self-coupling -- through double Higgs production. Studies exist, albeit with different levels of maturity, for the sensitivity of ILC500, ILC1000~\cite{cite:ILCTDR}, CLIC~\cite{cite:CLICDR}, and HL-LHC~\cite{cite:ATLAS,cite:CMS} to these couplings. From the HL-LHC estimates and the ttH and HH production cross sections at higher energies~\cite{Mangano_Rojo_2012}, extrapolations for $300~\infb$ of pp collision data at HE-LHC ($\sqrt{s} =$ 33 TeV) and VHE-LHC ($\sqrt{s}=$ 100 TeV) can be inferred. An executive summary is displayed in Fig.~\ref{fig:VHELHC}.