ICHEP 2016 - CLICdp(/ILC) abstract

Higgs physics at CLIC

• Speaker: Strahinja Lukic (Vinča Institute of Nuclear Sciences Belgrade, Serbia)
• Session: Higgs Physics
• Status: Accepted for oral presentation (ID 620) on behalf of the CLICdp collaboration
• Time: 15+5 min
• Abstract: The Compact Linear Collider (CLIC) is an option for a future multi-TeV electron-positron collider, offering the potential for a rich precision physics programme, combined with sensitivity to a wide range of new phenomena. The CLIC physics potential for measurements of the 125 GeV Higgs boson has been studied using full detector simulations for several centre-of-mass energies. The presented results provide crucial input to the energy staging strategy for the CLIC accelerator. The complete physics program for measurements of all accessible Higgs boson couplings is presented in this talk. All measurements available at a given centre-of-mass energy were included in combined fits. Operation at a few hundred GeV allows the couplings and width of the Higgs boson to be determined in a model-independent manner through the study of the Higgsstrahlung and WW-fusion processes. At a lepton collider, the measurement of the Higgsstrahlung cross section using the recoil mass technique with leptonic Z decays sets the absolute scale for all Higgs coupling measurements. Recently, it has been shown that this approach can be extended to hadronic decays of the Z boson which improves the statistical precision significantly. Operation at higher centre-of-mass energies provides large statistics for the study of Higgs boson decays and the potential to directly measure the top Yukawa coupling. At the highest centre-of-mass energy (presently assumed to be 3 TeV), the Higgs boson self-coupling can be determined with 10% precision.
• slides

BSM physics at CLIC

• Speaker: Rosa Simoniello (CERN)
• Session: Beyond the Standard Model
• Status: Accepted for oral presentation (ID 622) on behalf of the CLICdp collaboration
• Time: 15+5 min
• Abstract: The Compact Linear Collider (CLIC) is an option for a future electron-positron collider operating at centre-of-mass energies from a few hundred GeV up to 3 TeV. The search for phenomena beyond the Standard Model through direct observation of new particles and precision measurements is a main motivation for the high-energy stages of CLIC. An overview of physics benchmark studies assuming different New Physics scenarios is given in this presentation. These studies are based on full detector simulations. New particles can be discovered in a model-independent way almost up to the kinematic limit of sqrt(s) / 2. The low background conditions at CLIC provide extended discovery potential compared to hadron colliders, for example in the case of non-coloured TeV -scale SUSY particles. In addition to studying new particles directly, BSM models can be probed up to scales of tens of TeV through precision measurements. Examples, including recent results on the reaction e+ e- -> gamma gamma, are given. Beam polarisation allows to constrain the underlying theory further in many cases. The talk will also include discussion of LHC results relevant for the CLIC physics case.
• slides

Top physics at CLIC and ILC

• Speaker: Aleksander Filip Zarnecki (University of Warsaw)
• Session: Top Quark and Electroweak Physics
• Status: Accepted for oral presentation (ID 996)
• Time: 15+5 min
• Abstract: Measurements of top quark production at e+e- colliders can provide a leap in precision in our knowledge of top quark properties and open a new window on physics beyond the Standard Model. In this contribution the top quark physics prospects of linear colliders is reviewed. Progress in detailed full-simulation studies is reported for the highlights of the programme. We present the prospects for a measurement of the top quark mass and width in a scan of the beam energy through the pair production threshold, and discuss new studies of alternative measurements in continuum production, which are also capable of a precise determination of the mass in a rigorously defined mass scheme. A precision of ~50 MeV on the MSbar mass is expected when taking into account the dominant systematic uncertainties. Another key measurement is the study of the top quark couplings to electroweak gauge bosons, where form factors can be determined to 1% precision, an order of magnitude better than the full LHC programme. New results extend the prospects to different center-of-mass energies and to CP violating form factors. Finally, new studies are presented into the possibility at linear colliders to detect Flavour Changing Neutral Current decays of the top quark, such as the decay t -> cH, to a branching ratio BR(t->cH) ~ 10^-5.
• slides

Silicon pixel R&D for CLIC

• Speaker: Dominik Dannheim (CERN)
• Session: Detector: R&D and Performance
• Status: Accepted for oral presentation (ID 624) on behalf of the CLICdp collaboration
• Time: 12+3 min
• Abstract: The physics aims at the future CLIC high-energy linear e+e- collider set very high precision requirements on the performance of the vertex and tracking detectors. Moreover, these detectors have to be well adapted to the experimental conditions, such as the time structure of the collisions and the presence of beam-induced backgrounds. The principal challenges are: a point resolution of a few μm, ultra-low mass (~0.2% X0 per layer for the vertex region and ~1% X0 per layer for the outer tracker), very low power dissipation (compatible with air-flow cooling in the inner vertex region) and pulsed power operation, complemented with ~10 ns time stamping capabilities. A highly granular all-silicon vertex and tracking detector system is under development, following an integrated approach addressing simultaneously the physics requirements and engineering constraints. For the vertex-detector region, hybrid pixel detectors with small pitch (25 μm) and analog readout are explored. For the outer tracking region, both hybrid concepts and fully integrated CMOS sensors are under consideration. The feasibility of ultra-thin sensor layers is validated with Timepix3 readout ASICs bump bonded to active edge planar sensors with 50-150 μm thickness. Prototypes of CLICpix readout ASICs implemented in 65 nm CMOS technology with 25 μm pixel pitch have been produced. Hybridisation concepts have been developed for interconnecting these chips either through capacitive coupling to active HV-CMOS sensors or through bump-bonding to planar sensors. Recent R&D achievements include results from beam tests with all types of hybrid assemblies. Simulations based on Geant4 and TCAD are used to validate the experimental results and to assess and optimise the performance of various detector designs. The R&D project also includes the development of through-silicon via (TSV) technology, as well as various engineering studies involving thin mechanical structures and full-scale air-cooling tests. An overview of the R&D program for silicon detectors at CLIC will be presented.
• slides

Linear Collider Software and Computing

• Speaker: Nikiforos Nikiforou (CERN)
• Session: Computing and Data Handling
• Status: Accepted for oral presentation (ID 998)
• Time: 15+5 min
• Abstract: The ILC/CLIC linear collider community has for many years followed a strategy of developing common and generic software tools for studying the physics potential as well as continuously optimizing their detector concepts. The basis of the software framework is formed by the common event data model LCIO and the detector description toolkit DD4hep. DD4hep is a recently developed, generic detector description toolkit that allows to provide all aspects of detector geometry, materials and physics properties of the detector as needed for simulation, reconstruction and analysis from one single source of information. It offers an application framework for running full simulations with Geant4 as well as interfaces for handling conditions data and simulating mis-alignment of detector components. DD4hep has also been adopted by detector projects at FCC and CEPC. The proposed detectors for ILC and CLIC combine unprecedented momentum and impact parameter resolution with very high jet energy resolution, achieved with highly granular calorimeters and the application of particle flow reconstruction algorithms (PFA). The reconstruction algorithms for tracking and PFA are written as much as possible in a detector independent way, which on the one hand facilitates common software developments and on the other hand simplifies the comparison of different detector variants. For large scale Monte Carlo production and physics analyses the iLCDIRAC system provides a unified interface to the distributed computing resources used by the LC community. A simplified API allows to transparently submit jobs running all of the LC software to a large number of different batch and Grid-resources that are either directly provided or opportunistically available for the VO ILC. In this talk we will present the complete LC software for simulation and reconstruction with a focus on recent developments and application to ILD and the new CLIC detector model.
• slides