Session: Beyond the Standard Model

Prospects for Beyond Standard Model Physics at CLIC (544) (Philipp Roloff) Slides

The Compact Linear Collider (CLIC) is an attractive option for a future multi-TeV linear electron-positron collider. A staged construction in several centre-of-mass energy steps from a few hundred GeV up to 3 TeV is foreseen. At high energies, CLIC provides sensitivity to a wide range of phenomena beyond the Standard Model through direct observation of new particles and precision measurements. An overview of these opportunities is given in this presentation. CLIC is in particular well suited for the measurement of weakly interacting states due to the clean experimental conditions and low backgrounds compared to hadron colliders. Most studies are based on full detector simulations using Geant 4 and considering pileup from gamma gamma -> hadrons interactions. The production of supersymmetric particles like sleptons and gaugions was studied in detail in several different models. The scenarios discussed in this presentation include an extended Higgs sector, Z' physics and other models.

Session: Higgs physics

Higgs Physics at CLIC (546) (Eva Sicking) Slides

The Compact Linear Collider (CLIC) is an attractive option for a future multi-TeV linear electron-positron collider, offering the potential for a rich precision physics programme, combined with sensitivity to a wide range of new phenomena. The physics reach of CLIC has been studied in the context of three distinct centre-of-mass energy stages, 350 GeV, 1.4 TeV and 3.0 TeV. This staged scenario provides the ideal environment for precise studies of the properties of the ~125 GeV Higgs boson. Operation at 350 GeV allows the couplings and width of the Higgs boson to be determined in a model-independent manner through the study of the Higgs-strahulung and WW-fusion processes. Operation at higher centre-of-mass energies provides high statistics for even more precise measurements and the potential to study the top Yukawa coupling and even the Higgs boson self-coupling. In this talk we explore the potential of the CLIC Higgs physics programme, based on full simulation studies of a wide range of final states. The evolution of the physics sensitivity with centre-of-mass energy is presented in terms of model-independent coupling fits and the constrained kappa fits employed at the LHC.

SM-like Higgs decay into two muons at 1.4 TeV CLIC (571) (poster) (Gordana Milutinovic-Dumbelovic) Poster

The branching fraction measurement of the SM-like Higgs boson decay into two muons at 1.4 TeV CLIC will be presented. The study is performed in the fully simulated ILD detector concept for CLIC, taking into consideration all the relevant physics and beam-induced backgrounds, as well as instrumentation of the very forward region to tag high-energy electrons. In this analysis we show that BR times the Higgs production cross section can be measured with the 38% statistical accuracy in four years of the CLIC operation at 1.4 TeV center of mass energy. This study complements the Higgs physics program foreseen at various CLIC energy stages.

Session: Top-quark and electroweak Physics

Measurement of the top quark mass and couplings at Linear Colliders (Ignacio García García) Slides

The future precision studies of the Standard Model require excellent knowledge of the top quark mass, to an accuracy of 100 MeV or better. This mass can be measured in a way that is free of any ambiguities from soft QCD by locating the threshold position for e+e- annihilation to top quarks, or, more precisely, the mass of the unstable 1S resonance. The measurement requires a combination of precise QCD calculations, excellent detection efficiency and recognition of top quark events, and excellent control of the initial beam energy and profile. This contribution will report the current status of this program, with results from full-simulation studies of measurements of the top quark threshold in the detectors proposed for ILC and CLIC. Models in which the Higgs boson is composite or strongly interacting typically predict modifications of the coupling of the top quark to vector bosons and, in particular, to the Z boson. The production of the top quarks at e+e- colliders goes through the top quark couplings to the photon and the Z. Thus, precision studies of this pair production process, including its full dependence on electron and top quark polarization, has the potential to extract the form factors for the top quark couplings with high precision and in a model-independent way. This contribution will report the current status of this program, with results from full-simulation studies of top quark pair production in the detectors proposed for ILC and CLIC.

Session: Detector R&D and Performance

CLIC detector: performance optimisation for e+e- physics above 1 TeV and status of the corresponding R&D activities (547) (Marcel Demarteau) Slides

Detectors at CLIC are optimised for precision e+e- physics at multi-TeV centre-of-mass energies, as well as for the CLIC-specific beam timing conditions and beam-induced background processes. The talk will provide an overview of these requirements, illustrated on the basis of example physics benchmark processes, and show how optimal physics performance can be achieved under these conditions. The resulting requirements set very high demands on sub-detector capabilities. The vertex and tracking detectors require very small cell sizes and hit timing at the 10 ns level, as well as ultra-low mass, facilitated by power pulsing and air cooling. The calorimetry calls for ultra dense solutions with high granularity, large dynamic range and hit timing at the 1 ns level. Detector R&D following these stringent requirements is progressing well in several areas. A status report on the innovative detector R&D efforts for CLIC will be included in the presentation.

Vertex detector R&D for CLIC (548) (poster) (Philipp Roloff) Poster

A future CLIC vertex detector must satisfy the precision physics needs and be compatible with the challenging beam structure at CLIC. As a result the pixel detector is required to have excellent spatial resolution, precise time-tagging, full geometrical coverage, extremely low mass, low occupancy and sufficient heat removal from sensors and readout. A vertex detector concept based on two hybrid pixel-detector options (with silicon sensors or with a HV-CMOS sensor pre-stage) forms the basis of an active integrated R&D effort that pushes technology to its limits. It comprises fast, low-power and small-pitch readout ASICs implemented in 65 nm CMOS technology (CLICpix) coupled to ultra-thin sensors via low-mass interconnects. The power dissipation of the readout chips is reduced by means of power pulsing, allowing for a cooling system based on forced gas flow. In this presentation the CLIC vertex-detector requirements are reviewed and the current status of R&D on sensors, readout and detector integration, including results of recent beam tests are presented.

-- MaxChefdeville - 23 Apr 2014