LCWS14 - International Workshop on Future Linear Colliders

Abstracts

WG1: Plenary talks

Higgs physics at CLIC and future prospects

• Speaker: Philipp Roloff (CERN)
• Abstract: not needed

CLICdp status

• Speaker: Sophie Redford (CERN)
• Abstract: not needed

WG2: Higgs/EW

H->bb/cc/gg at 350 GeV at CLIC

• Status: accepted
• Speaker: Marco Szalay (MPI Munich)
• Abstract: With precise flavor tagging and the reconstruction of hadronic final states, CLIC is capable of measuring the branching fractions of the decay of the Higgs boson into bottom and charm quarks and gluons. A study of the prospects for this measurement at 350 GeV has been performed in full detector simulations with realistic machine-induced and physics background levels. At the initial energy stage of CLIC of 350 GeV, Higgs production both via Higgsstrahlung and via vector boson fusion contributes significantly to the total signal, which enables a simultaneous measurement of both production modes.
• Time: 15+2 min

Combined fits of Higgs couplings at CLIC

• Status: accepted
• Speaker: Frank Simon (MPI Munich)
• Abstract: To evaluate the impact of the full CLIC program on the knowledge of the Higgs couplings, a combined fit of all results of the Higgs physics studies at CLIC is performed. This fit includes the treatment of correlations of different measurements, which are substantial in the case of hadronic Higgs decays and for the extraction of the contributions of Higgsstrahlung and vector boson fusion at 350 GeV. Two fit scenarios will be presented - one model-independent fit, and another model-dependent fit assuming that the total width is described by the sum of nine visible final states, with coupling parameters given by the deviation of the respective partial widths from their SM values.
• Time: 15+2 min

H->ZZ* at 1.4 TeV and Higgs production in ZZ fusion

• Status: accepted
• Authors: Gordana Milutinovic-Dumbelovic (Belgrade), Aidan Robson (Glasgow)
• Speaker: Gordana Milutinovic-Dumbelovic (Belgrade)
• Abstract: The studies presented in this talk are part of an effort to investigate the complete physics potential of a CLIC collider operated at various energies for measurements of the SM Higgs boson properties. The physics potential for measuring both the cross section times branching ratio of the decay H->ZZ* at 1.4 TeV, and the cross section for Higgs production in ZZ fusion at 1.4 TeV, will be presented. In e+e- collisions at a centre-of-mass energy of 1.4 TeV, the SM-like Higgs boson with a mass of 126 GeV is dominantly produced via W+W- fusion. The purely hadronic final state (ZZ*->qqqq) is considered as well as Z decays with two jets and two leptons in the final state (ZZ*->qqll). The related process of Higgs produced through ZZ fusion, is the sub-leading Higgs production mechanism at 1.4TeV, and a measurement of this process contributes to the determination of the HZZ coupling. The analyses are based on a full simulation of the CLIC_ILD detector. All relevant SM background processes are considered, and beam-induced background from gamma gamma->hadrons interactions is overlaid to the physics events.
• Time: 15+2 min

Physics potential for the measurement of the Higgs boson decay to tau leptons at CLIC

• Status: accepted
• Authors: Astrid Münnich (DESY), Philipp Roloff (CERN)
• Speaker: Philipp ROLOFF (CERN)
• Abstract: The study presented in this talk is part of an effort to investigate the complete physics potential of a CLIC collider operated at various energies for measurements of the SM Higgs boson properties. The production cross section times branching ratio for the decay H -> tau+tau- is measured using hadronic tau decays at centre-of-mass energies of 350 GeV, 1.4 TeV and 3 TeV. The analysis is based on a full detector simulation using Geant4. Beam-induced backgrounds from gamma gamma -> hadrons interactions are overlaid to the physics events.
• Time: 15+2 min

Update on the top Yukawa coupling measurement at 1.4 TeV CLIC

• Status: accepted
• Authors: Sophie Redford (CERN), Philipp Roloff (CERN), Marcelo Vogel (University of Santiago)
• Speaker: Sophie Redford (CERN)
• Abstract: The physics potential for a direct measurement of the top Yukawa coupling using the process e+e- -> ttH at a CLIC collider operated at 1.4 TeV is investigated. Final states with six and eight jets are reconstructed. This study addresses various aspects of the detector performance: jet clustering in complex hadronic final states, missing energy reconstruction, flavour-tagging and the identification of high-energy leptons. The analysis is based on a full detector simulation using Geant4. Beam-induced backgrounds from gamma gamma -> hadrons interactions are overlaid to the physics events. For the first time, the impact of non-ttbar(+X) backgrounds on the analysis will be presented. These additional backgrounds do not significantly impact the existing result.
• Time: 15+2 min

Measurement of the H-> WW* decay at 350 GeV and 1.4 TeV CLIC

• Status: accepted
• Authors: Mark Thomson (Cambridge), Mila Pandurovic (Belgrade)
• Speaker: Mila Pandurovic (Belgrade)
• Abstract: The study presented in this talk is part of an effort to investigate the complete physics potential of a CLIC collider operated at various energies for measurements of the SM Higgs boson properties. The physics potential for measuring the cross-section times branching fraction of the decay H->WW*->qqqq, at different energy stages of CLIC operation, is presented. The studies are performed using the leading Higgs production channels at each centre-of-mass energy, Higgsstrahlung at 350 GeV and WW fusion at 1.4 TeV. These complementary measurements will determine the Higgs boson couplings to vector bosons and contribute to the determination of the total Higgs width. The analysis is based on a full simulation of the CLIC_ILD detector.
• Time: 15+2 min

WG3: BSM

WG4: Simulation/Detector Performance/Reconstruction

Simulation studies for the CLIC vertex detector

• Status: accepted
• Speaker: Niloufar ALIPOUR TEHRANI (ETH Zurich and CERN)
• Abstract: A vertex-detector concept based on the hybrid planar pixel-detector technology is currently under development for CLIC. Geant4-based full-detector simulations are used to assess the influence of the proposed detector layouts and technologies on the flavour-tagging performance. TCAD device simulations and Geant4 simulations using a sensor and electronics digitisation model are used to optimise the sensor and readout ASIC design and for comparisons with measurements on prototypes. In this talk we present the status of several ongoing simulation studies.
• Time: 20 min
• Note: preferably in a combined session of Vertex / Tracking & Simulation / Detector performance / Reconstruction

CLIC tracking studies

• Status: accepted
• Speaker: Rosa SIMONIELLO (CERN)
• Abstract: A CLIC detector concept with a full silicon tracker is currently being optimised. In this talk the tracking performances are evaluated using both the full detector simulation based on Geant4 and the fast detector simulation based on LDT (Linear collider Detector Toy) software. The results are discussed for the different tracking detector dimensions, layouts and for several values of the magnetic field. The impact on the performance of a realistic rather than a homogenous magnetic field is also investigated.
• Time: 20 min

ILCdirac: Status and Plans

• Status: accepted
• Speaker: Andre SAILER (CERN)
• Abstract: The recent developments of the ILCDirac grid interware are presented. A short review of the performance, problems, and an outlook for the future will be shown. In addition a very brief reminder about basic functionality and support channels will be given.
• Time: 20 min

First look at flavour tagging at CLIC using LCFIPlus including beam-induced backgrounds

• Status: accepted
• Speaker: Philipp ROLOFF (CERN)
• Abstract: The identification of beauty and charm jets at CLIC is investigated using a full detector simulation based on Geant4. Pile-up from gamma gamma -> hadrons interactions is included in the event simulation. The flavour tagging performances obtained for different jet reconstruction strategies targeted to reduce the impact of the pile-up are compared.
• Time: 10 min

WG5: Machine Detector Interface/Integration/Polarisation

CLIC detector B-field with reduced end-cap yoke (20 min)

• Proposed speaker: Benoit CURE, CERN
• Abstract: In attempt to reduce the overall length of a future CLIC detector, a study has been performed on the CLIC_SiD concept. The end-cap iron yoke has been strongly reduced in thickness. The field quality and the stray field characteristics are recovered by introducing a system of coils on both outer ends of the reduced end-cap yoke. This talk will present the results of the study, which concludes that reducing the end-cap yoke is feasible, without detrimental effects on magnetic field quality, albeit at the price of increased power consumption due to the compensating end-coils.

WG6: Vertex/Tracking

Characterisation of Timepix3 and CLICpix hybrid pixel detector assemblies

• Proposed speaker: Samir Arfaoui (CERN)
• Abstract: A vertex detector concept based on the hybrid planar pixel detector technology is currently under development for the proposed Compact Linear Collider (CLIC). Assemblies using thin planar pixel sensors (50-300 um) hybridised with Timepix readout ASICs have been characterised in previous testbeams at DESY. In this talk we present the integration in the AIDA telescope infrastructure as well as measurements performed with the new Timepix3 ASIC coupled to a 300um thick sensor at the CERN Proton Synchrotron in August 2014. First measurements on the 25 um pitch CLICpix ASIC coupled to a CCPDV3 active HV-CMOS sensors will also be shown.

Calibration and test-beam characterization for hybrid-pixel readout assemblies with ultra-thin sensors (25 min)

• Proposed speaker: Sophie REDFORD, CERN
• Abstract: A vertex-detector concept based on the hybrid planar pixel-detector technology is currently under development for CLIC. To reach the low material budget of 0.2% X0 per layer, sensors and readout ASICs will each have to be thinned down to approximately 50 um. In a first phase of R&D, assemblies were produced using thin planar pixel sensors (50-300 um) hybridised to Timepix readout ASICs. Both standard thickness ASICs and ASICs thinned to 100 um are used. Sensors include active-edge sensors from Advacam with 50 um thickness and Micron semiconductor sensors with 100 um thickness hybridised by IZM. The assemblies have been calibrated with sources and X-ray fluorescence measurements and characterised in beam telescope tests at DESY with a 5.5 GeV electron beam. In this talk we present the current status of sensor calibration and test-beam analysis.

Cooling and vibration studies of a CLIC vertex detector (25 min)

• Proposed speaker: Fernando DUARTE RAMOS, CERN
• Abstract: In view of the strict requirements in terms of material budget and position stability in the inner tracker and vertex detector of a future CLIC detector, novel ideas have been proposed for the air cooling and mechanical support of these detectors. This talk is an update of the mechanical engineering studies for the CLIC innermost detectors. It is focused on the ongoing experimental cooling studies and the development of lightweight detector support structures that fulfil both mass and stiffness requirements.

WG7: Calorimetry/Muon Systems

(Abstracts submitted via CALICE and FCAL)

Overview of FCAL activities

• Proposed speaker: O. Borysov, Tel Aviv Universit, Israel
• Abstract: The talk focuses on the instrumentation of the very forward region of the linear collider detectors which in the present conceptual design are equipped with LumiCal and BeamCal electromagnetic calorimeters. These detectors aim at measuring the instantaneous and integrated luminosity, the latter with high precision, and at extending the detector coverage to low polar angles to enhance the potential of various physics analyses. Recent activities on detectors, electronics and software development to achieve the required performance are presented. Included are tests of detector modules and sensors made of different materials, as well as studies of the detector design to improve position reconstruction, particle identification and luminosity spectrum measurements. Future plans for readout electronics development are also discussed.

Electronics for FCAL detectors

• Proposed speaker: Angel Abusleme, Pontificia Universidad Catolica de Chile / Santiago, Chile
• Abstract: This presentation shows the current status and future plans of the readout electronics for the Luminosity Detector (LumiCal) and Beam Calorimeter (BeamCal) at the International Linear Collider ILC. For LumiCal, we present the status of the front-end and ADC ASICs developed in AMS 0.35-um technology, followed by the status and plans of new readout electronics ICs in 130-nm technology. For BeamCal, we present the design and results of our previous front-end and readout IC that includes charge-sensitive amplifiers, filters and ADCs. We also show our current status that includes a new ADC and an improved front-end. Finally we present a theoretical development towards the implementation of a nonlinear ADC for BeamCal.

WG8: Top/QCD/Loopverein

Special parallel session on detector optimisation

Summary of CLICdp detector optimisation studies

• Speaker: Rosa Simoniello (CERN)
• Abstract: not needed

-- EvaSicking - 19 Aug 2014