The 2-day meeting on the CLIC detector and physics study will start on Tuesday 29 August 08:30 and will end on Wednesday 30 August around 17:30. Most of the time will be devoted to topical sessions, providing an overview of ongoing activities and future plans. In order to allow the participants to get a good overview of the work in CLICdp, we try to avoid parallel sessions. The timetable presently proposed is tentative - sessions can be shortened/extended at a later stage, according to the proposed number of talks.
We foresee to have the following topical sessions (and conveners):
A CLICdp Institute Board meeting is scheduled for Tuesday lunchtime, 29 August.
The workshop dinner is scheduled for Tuesday evening, 29 August, 19h30 at La Maison d'Asie in Geneva (cost: 50 CHF all included).
Prospects for measuring top FCNC decays at 380 GeV were studied with the full simulation samples including signal sample generated with the WHIZARD implementation of the 2HDM(III) model and the standard six-fermion event samples used for top pair production studies. Analysis was divided into three steps: event classification, 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 Tree (BDT) responce were used at each step. Expected limits on BR(t->cH)*BR(H->bb) are presented.
15 minutes presentation + 5 minutes discussion
In the Standard Model, FCNC top decays, are very strongly suppressed. Observing such a decay would be a direct signature of physics beyond the SM as large enhancements are possible in many "new physics" scenarios. A full simulation study for CLIC at 380 GeV based on a WHIZARD simulation of FCNC top decay t -> c gamma within the 2HDM(III) model is performed. An update on this analysis including background suppression of standard top decay channels (cut based and TMVA) is presented, including a first estimate of the discovery limit.
15 minutes presentation + 5 minutes discussion
The CLIC sensitivity to the QED process ee->gamma gamma
at 3 TeV is studied using SiD geometry model.
The estimated precision on total and differential
cross-sections is converted into the exclusion limits
on various New Physics models, including finite electron size,
extra dimensions, contact interactions, excited electrons.
Sensitivity studies of the BSM Hidden Valley particles have been performed for the e+e- collisions at the centre-of-mass energy of 3 TeV in the CLIC detector,
corresponding to an integrated luminosity of 2 ab-1. Hidden Valley particles may be stable, providing dark matter candidates and missing energy signals,
but others may decay into neutral combinations of Standard Model particles. Since the Higgs boson may also decay into two Hidden Valley particles, providing
four b-jets in the final state which are away from the primary vertex and the beam axis, analysis relies on loosely reconstructed displaced vertices assigned to the b-jets.
The final aim of the present analysis is to determine the upper limits of the cross sections for the Hidden Valley particle production for different masses and lifetimes.
We study the reach on the Higgs coupling constraints at future lepton colliders in a global effective-field-theory framework. The impact and complementarity of different measurements, at different center-of-mass energies and for several beam polarization configurations, are discussed in detail. This framework is also applied to study the constraints on the Higgs self-coupling. Based on arXiv:1704.02333 and current study.
12 minutes presentation + 3 minutes discussion
https://indico.cern.ch/event/656038/
The precision on the top Yuakwa coupling is measured in the e+e -->t ̄tH process at sqrt(s) = 1.4 TeV using Compact Linear Collider (CLIC). The analysis focuses on the 6 jets and 8 jets final states channels using particle flow technique. Leptons are identified first follow by clustering the remaining particles into jets and removing the beam jets. Particles that are not identified as leptons are reclustered into jets and performed flavour-tagging. Optimal selection are investigated to select leptons and to suppress the beam-induced backgrounds. Collection of variables are used as input to the BDT to select signals. The precision of the top Yukawa coupling in the semi-leptonic channel is determined to be 5.92% with no beam polarisation.
12 minutes presentation + 3 minutes discussion
15 minutes presentation + 5 minutes discussion
In this contribution we outline the path towards studying top quark properties at the multi-TeV collisions of the CLIC physics programme. We discuss the jet reconstruction performance utilising a fat-jet approach and subsequent methods to identify the underlying top sub-structure in boosted topologies. We present results on the cross-section and forward-backward asymmetry as well as an interpretation of the results from the full CLIC programme in terms of EFT operators.
15 minutes presentation + 5 minutes discussion
In this talk I will report on recent progress in the implementation of threshold resummation into the Monte Carlo event generator WHIZARD. This is crucial for reliable predictions of WWbb production close to the top-antitop threshold. As a key feature we establish a smooth transition between the threshold region and the relativistic (NLO) continuum. For the first time our code allows to study arbitrary differential observables involving the decay products of the tops and including interference with non-resonant background processes at threshold and beyond.
15 minutes presentation + 5 minutes discussion
I will present an update of the study of the top mass measurement and other top properties in a threshold scan, now using the luminosity spectrum of the new CLIC baseline machine. The optimisation of the machine for 380 GeV instead of 500 GeV leads to increased beamstrahlung when operated in the top threshold region, which may result in a degradation of the sensitivity of a threshold scan. The impact of this change will be discussed in the presentation.
12 minutes presentation + 3 minutes discussion