Future Linear Colliders: Detector R&D, Jet Reconstruction and Top Physics Potential

During the 20th century, discoveries and measurements at colliders, combined with progress in theoretical physics, allowed us to formulate the Standard Model of the in- teractions between the constituents of matter. Today, there are two advanced projects for a new installation that will collide electrons and positrons covering an energy range from several hundreds of GeV to the multi-TeV scale, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). These Future Linear Colliders give the opportunity to study the top quark with unprecedented precision. Measurements of top quark properties are of special interest, as the top quark is the heaviest ele- mentary particle of the SM. Precision measurements of top quark properties at e+e colliders promise therefore to be highly sensitive to physics beyond the SM. This thesis has three complementary parts. The first is dedicated to the R&D of the ILD detector concept for future e+e- colliders, more precisely, the innermost region of the detector. A thermo-mechanical characterization of ultra-thin self-supporting silicon sensors is carried out and a first mock-up of the forward tracker is designed and characterized. Additionally, the possibility of integrated micro-cooling circuits in the active silicon sensors is demonstrated. The program of precision physics scheduled for future colliders requires excellent detectors, but it also demands the best reconstruction algorithms. In the second part of the thesis the jet reconstruction performance is evaluated at different centre-of-mass energies and a new sequential jet reconstruction algorithm is proposed to deal with the expected gamma gamma > hadrons background levels at ILC and CLIC. The last part is focused on the top quark physics potential of future colliders. I demonstrate that both projects can constrain the top quark CP-conserving electro- weak couplings and CP-violating couplings to the % level. The potential of an e+e- collider with polarized beams, an integrated luminosity of 500 fb 1 and centre-of- mass energies of 500 GeV for ILC or 380 GeV for CLIC is studied in full simulation. The sensitivity to new physics is over an order of magnitude with respect to what is expected from LHC.