LCWS17 - International Workshop on Future Linear Colliders

Abstracts

Session: Plenary talks

Title: CLICdp status talk

• Speaker: Marko Petric (CERN)
• Status: Invited
• Allocated time: 20 min
• Abstract: not needed

Session: Higgs/EW

Session: BSM

Title: Search for new physics with ee -> gamma gamma at CLIC

• Speaker: Igor Boyko
• Status: Accepted
• Time: 20 min
• Abstract:The CLIC sensitivity to measure the process ee->gamma gamma has been studied in full CLIC simulations. The measurements can be interpreted in terms of various new physics models, including finite size electrons, excited electrons, contact interactions, graviton exchange in extra dimensions. The sensitivity to a new physics scale for CLIC running at 3 TeV is estimated to be in the range of 5 to 20 TeV.

Session: Top/QCD/Loopverein

Title: Limits on top FCNC decay t->cH and t->c gamma from CLIC at 380 GeV

• Speaker: Aleksander Filip Zarnecki
• Status: Accepted
• Time: 20 min
• Abstract: FCNC top decays are very strongly suppressed in the Standard Model. Observation of any such decay would be a direct signature of the physics beyond SM. Many "new physics" scenarios predict new contributions to FCNC processes and the largest engancement is in most cases expected for t->cH decay. Enhancements for the decay channel t->c gamma are more modest, but the decay has a clearly identifiable kinematic signature. Prospects for measuring these decays at CLIC running at 380 GeV were studied with full detector simulation, taking luminosity distribution, beam polarization and beam induced background into account. Top pair production events with FCNC decay t->cH can be identified based on the kinematic constrains and flavour tagging information. Analysis was divided into three steps: classification of top pair candidate events, event quality determination and kinematic reconstruction based on signal or background hypothesis, and final signal vs background discrimination. To obtain optimal results, selection criteria based on the dedicated Boosted Decision Trees (BDT) were used at each step. The expected limit on BR(t->cH)*BR(H->bb) is presented from a combined analysis of hadronic and semi-leptonic top pair samples, as well as the limit on BR(t->c gamma) from hadronic top pair decays.

Title: Top EW couplings (CLIC/ILC)

• Speaker: Martín Perelló Roselló
• Status: invited
• Time: 20 min
• Abstract: We will present a general status of the top quark couplings studies for the process e-e+ > tt~. Recent studies at CLIC380 and ILC500 allowed us to put bounds on the couplings in a form-factor scheme, including CP-violating couplings. In this talk we’ll present a new study including contact interaction through an effective field theory (EFT) approach. For this purpose we aim to include predictions at high-energy operation where events are substantially boosted and therefore need new reconstruction techniques. Preliminary results for a boosted top tagger will be presented, showing its potential at CLIC multi-TeV stages. Further, we will show preliminary results for effective dim-6 operators based on the predicted uncertainty on cross-section and forward-backward asymmetry. Statistically optimal observables are introduced as an alternative to potentially improve the fit.

Title: Radiative top mass contribution (CLIC/ILC)

• Speaker: Pablo Gomis
• Status: Accepted
• Time: 20 min
• Abstract: An e-e+ linear collider running at energies above the top production threshold will provide an unprecedented precision on the top-quark mass measurement. Complementary to the measurement at the threshold we propose to use radiative events in the ttbar pair production in the continuum to measure the top-quark mass. In this presentation, we will show that a high precision is possible at the order of 100-150 MeV depending on the running scenarios of future e+e- collider. The study uses generated Monte Carlo events and the observable to perform the measurement is defined as the differential cross section of the ttbar + ISR photon as a function of the ttbar invariant mass. Results are shown at parton and particle level. The positive results encourage extending the study to include fully simulated events through the detector. We will also discuss some of the experimental aspects related with the selection of the full simulation sample including the luminosity spectrum smearing correction. The theoretical frame to extract the top-quark mass value will also be discussed.

Session: Simulation/Reconstruction/Detector-performance

Title: Particle Flow and Forward Calorimeter Performance for the CLIC Detector

• Speaker: André Sailer
• Status: Accepted
• Time: 20 min.
• Note: For combined Sim/Reco and Calorimeter session
• Abstract: We will give a report on the current status and recent improvements of the particle flow and forward calorimeter performance of the CLIC detector model.

Title: Linear Collider Software in CLIC

• Speaker: André Sailer
• Status: Accepted
• Time: 20 min.
• Abstract: We will give a status report for the developments and use of the iLCSoft for the CLIC detector and physics studies, and discuss our plans beyond the next large scale Monte Carlo campaign.

Title: iLCDirac Status and Plans

• Speaker: Marko Petric
• Status: Accepted
• Time: 20 min.
• Abstract: We will present the current status and plans for iLCDirac.Furthermore we will discuss the evolution of available sites and resources and will give and an overview of new features and current developments.

Session: Vertex/Tracking

Title: R&D for the CLIC vertex detector

• Speaker: Dominik Dannheim
• Status: submitted
• Proposed time:
• Abstract: A highly granular pixel detector system is under development for the vertex detector at the CLIC high-energy linear e+e- collider. This contribution gives an overview of the ongoing technology R&D. The focus will be on recent results from laboratory and test-beam measurements of the new CLICpix2 readout ASIC prototypes capacitively coupled to active High-Voltage CMOS sensors (C3PD).

Title: R&D for the CLIC tracker

• Speaker: Magdalena Munker
• Status: submitted
• Proposed time:
• Abstract: An all-silicon tracker is under development for the CLIC high-energy linear e+e- collider. We introduce the detector requirements and the proposed tracker layout and present recent results from beam tests of different monolithic sensor prototypes implemented in High-Resistivitiy (HR) CMOS and Silicon-on-Insulator (SOI) process technologies.

Title: Tracking validation with performances of the CLIC detector model and of the CLIC-like detector for FCCee

• Speaker: Emilia Leogrande
• Status: Submitted
• Proposed time:
• Note: For combined performance/tracking session
• Abstract: This talk focuses on the validation of the current reconstruction software and tracking algorithm developed for the CLIC detector in the iLCSoft framework. Great effort has been deployed in updating the pattern recognition strategy and improving the track fit. This results in optimized performances of the all-silicon tracking system of the new CLIC detector model, in terms of resolutions, efficiency and flavour tagging, which will be presented in detail. Moreover, the same simulation and reconstruction tools have been used in a straightforward way to study the performances of the CLIC-like detector for FCCee, proving the versatility of the framework in completely different interaction regions and beam conditions.

Session: Calorimeters/Muon

• Submitted via CALICE, FCAL, HGCal

Session: MDI/Integration/Polarization

Title: Beam-induced backgrounds at CLIC

• Speaker: Dominik Arominski
• Status: Accepted
• Time: 20 min.
• Note: The talk is targeted at the joint Machine-detector Interface - Beam Dynamics session
• Abstract: This presentation concerns the beam-induced background results in the CLIC Machine-detector Interface of the different designs of the Beam Delivery System and their impact on the detector performance. Detector safety and luminosity tuning procedure studies done for CLIC pointed out a need to change the distance from the last quadrupole to the Interaction Point, called L*, by moving the magnet outside the detector, effectively extending the L* to 6 meters. This modification has a significant impact on the yields and momentum distributions of the produced beam-induced backgrounds, as well as on the luminosity spectrum. These differences and their impact have been studied and are thoroughly described for the lowest energy stage of CLIC at 380 GeV.