No Arabic abstract
The physics programme for a coming electron linear collider is dominated by events with final states containing many jets. We develop in this paper the opinion that the best approach is to optimise the independent measurement of the tracks in the tracker, the photons in the electromagnetic calorimeter and the neutral hadrons in the camorimetry, together with a good lepton identification. This can be achieved with a high granularity calorimetry providing particle separation, through an efficient energy flow algorithm.
A comprehensive review of physics at an e+e- Linear Collider in the energy range of sqrt{s}=92 GeV--3 TeV is presented in view of recent and expected LHC results, experiments from low energy as well as astroparticle physics.The report focuses in particular on Higgs boson, Top quark and electroweak precision physics, but also discusses several models of beyond the Standard Model physics such as Supersymmetry, little Higgs models and extra gauge bosons. The connection to cosmology has been analyzed as well.
We carried out a feasibility study on the measurement of the branching ratio of H -> cc_bar at a future e+e- linear collider. We used the topological vertex reconstructing algorithm for accumulating secondary vertex information and the neural network for optimizing c quark selection. With an assumption of a light Higgs mass of 120 GeV/c^2, we estimated the statistical error of Br(H -> cc_bar) to be 20.1% or 25.7% depending on the number of vertex detector layers at the center-of-mass energy of 250 GeV and the intergrated luminosity of 500 fb^-1.
The scalar top discovery potential has been studied with a full-statistics background simulation for sqrt(s) = 500 GeV and L = 500 fb-1. The simulation is based on a fast and realistic simulation of a TESLA detector. The large simulated data sample allowed the application of an Iterative Discriminant Analysis (IDA) which led to a significantly higher sensitivity than in previous studies. The effects of beam polarization on signal efficiency and individual background channels are studied using separate optimization with the IDA for both polarization states. The beam polarization is very important to measure the scalar top mixing angle and to determine its mass. Simulating a 180 GeV scalar top at minimum production cross section, we obtain Delta(m) = 1 GeV and Delta(cos(theta)) = 0.009.
The Compact Linear Collider, CLIC, is a proposed e$^+$e$^-$ collider at the TeV scale whose physics potential ranges from high-precision measurements to extensive direct sensitivity to physics beyond the Standard Model. This document summarises the physics potential of CLIC, obtained in detailed studies, many based on full simulation of the CLIC detector. CLIC covers one order of magnitude of centre-of-mass energies from 350 GeV to 3 TeV, giving access to large event samples for a variety of SM processes, many of them for the first time in e$^+$e$^-$ collisions or for the first time at all. The high collision energy combined with the large luminosity and clean environment of the e$^+$e$^-$ collisions enables the measurement of the properties of Standard Model particles, such as the Higgs boson and the top quark, with unparalleled precision. CLIC might also discover indirect effects of very heavy new physics by probing the parameters of the Standard Model Effective Field Theory with an unprecedented level of precision. The direct and indirect reach of CLIC to physics beyond the Standard Model significantly exceeds that of the HL-LHC. This includes new particles detected in challenging non-standard signatures. With this physics programme, CLIC will decisively advance our knowledge relating to the open questions of particle physics.
This paper summarizes the physics potential of the CLIC high-energy e+e- linear collider. It provides input to the Snowmass 2013 process for the energy-frontier working groups on The Higgs Boson (HE1), Precision Study of Electroweak Interactions (HE2), Fully Understanding the Top Quark (HE3), as well as The Path Beyond the Standard Model -- New Particles, Forces, and Dimensions (HE4). It is accompanied by a paper describing the CLIC accelerator study, submitted to the Frontier Capabilities group of the Snowmass process.