Top-quark physics at the CLIC electron-positron linear collider

ABSTRACT: The Compact Linear Collider (CLIC) is a proposed future high-luminosity linear electron-positron collider operating at three energy stages, with nominal centre-of-mass energies √s = 380 GeV, 1.5 TeV, and 3 TeV. Its aim is to explore the energy frontier, providing sensitivity to physics beyond the Standard Model (BSM) and precision measurements of Standard Model processes with an emphasis on Higgs boson and top-quark physics. The opportunities for top-quark physics at CLIC are discussed in this paper. The initial stage of operation focuses on top-quark pair production measurements, as well as the search for rare flavour-changing neutral current (FCNC) top-quark decays. It also includes a top-quark pair production threshold scan around 350 GeV which provides a precise measurement of the top-quark mass in a well-defined theoretical framework. At the higher-energy stages, studies are made of top-quark pairs produced in association with other particles. A study of t̄tH production including the extraction of the top Yukawa coupling is presented as well as a study of vector boson fusion (VBF) production, which gives direct access to high-energy electroweak interactions. Operation above 1 TeV leads to more highly collimated jet environments where dedicated methods are used to analyse the jet constituents. These techniques enable studies of the top-quark pair production, and hence the sensitivity to BSM physics, to be extended to higher energies. This paper also includes phenomenological interpretations that may be performed using the results from the extensive top-quark physics programme at CLIC.the Spanish Ministry of Economy, Industry and Competitiveness under projects MINEICO/FEDER-UE, FPA2015-65652-C4-3-R, FPA2015-71292-C2-1-Pand FPA2015-71956-REDT; and the MECD grant FPA2016-78645-P, Spai

Top Quark Precision Physics at Linear Colliders

Linear $e^+e^-$ colliders provide a rich set of opportunities for precision top physics, crucial for the understanding of electroweak symmetry breaking and for the search for physics beyond the Standard Model. A $t\bar{t}$ threshold scan in $e^+e^-$ annihilation enables a precise measurement in theoretically well-defined mass schemes with small experimental and theoretical systematic uncertainties. Above the production threshold, the efficient identification of top pair events combined with polarized beams provides the potential to extract the form factors for the top quark couplings with high precision and in a model-independent way, resulting in excellent sensitivity to physics beyond the Standard Model. This contribution provides an overview of top physics at linear colliders based on results from full-simulation studies of top quark pair production in the detectors proposed for ILC and CLIC

An Annotated Reference Guide to the Finite-Element Interface Specification Version 1.0

The Finite-Element Interface (FEI) specification provides a layered abstraction that permits finite-element analysis codes to utilize various linear-algebra solution packages with minimal concern for the internal details of the solver modules. Alternatively, this interface can be viewed as a way for solver developers to provide solution services to finite-element clients without having to embed finite-element abstractions within their solver libraries. The purpose of this document is to provide some level of documentation between the bare interface specification itself, which consists only of C/C++ header files, and the full documentation suite that supports the interface definition by providing considerable detail as to its design and implementation. This document primarily provides the ''how'' of calling the interface member functions, so that programmers can readily learn how to utilize the interface implementation without having to consider all the details contained in the interface's definition, design, and motivation. The interface specification is presented three times in this document, each time with an increasing level of detail. The first presentation provides a general overview of the calling sequence, in order to acquaint the programmer with a basic introduction to how the interface is used to ''train'' the underlying solver software on the particular finite-element problem that is to be solved. The second pass through the interface definition provides considerable detail on each method, including specific considerations as to the structure of the underlying data, and an exposition of potential pitfalls that may occur as a byproduct of either the finite-element modeling process, or of the use of the associated interface implementation. Finally, a third description of the interface is given implicitly via the discussion of sample problems that provide concrete examples of the use of the finite-element interface

Measurement Of The Branching Ratios For The Standard Model Higgs Decays Into Muon Pairs And Into Z Boson Pairs At A 1.4 TeV CLIC

The measurement of the Higgs production cross-section times the branching ratios for its decays into mu(+)mu(-) and ZZ* pairs at a 1.4 TeV CLIC collider is investigated in this paper. The Standard Model Higgs boson with a mass of 126 GeV is dominantly produced via WW fusion in e(+)e(-) collisions at 1.4 TeV centre-of-mass energy. Analyses of both decay channels are based on a full simulation of the CLIC_ ILD detector. All relevant physics and beam-induced background processes are taken into account. An integrated luminosity of 1.5 ab(-1) and unpolarised beams are assumed. For the H - GT ZZ* decay, the purely hadronic final state (ZZ* - GT q (q) over barq (q) over bar) is considered as well as ZZ* decays into two jets and two leptons (ZZ* - GT qql(+)l(-)). It is shown that the branching ratio for the Higgs decay into a muon pair times the Higgs production cross-section can be measured with 38% statistical uncertainty. It is also shown that the statistical uncertainty of the Higgs branching ratio for decay into a Z boson pair times the Higgs production crosssection can be measured with a precision of 18.3% and 5.6% for the hadronic and semi-leptonic ZZ* decays, respectively.9th International Physics Conference of the Balkan-Physical-Union (BPU), Aug 24-27, 2015, Istanbul Univ, Beyazit Campus, Istanbul, Turke