A Highly Granular Silicon-Tungsten Electromagnetic Calorimeter and Top Quark Production at the International Linear Collider

1 The Standard Model of Particles Physics 15 1.1 The Particles of the Standard Model . . . . . . . . . . . . . . . . . 15 1.1.1 The fermions . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1.1.2 The Bosons . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.2 The Fundamental Forces in the Standard Model . . . . . . . . . . . 17 1.2.1 A simple example: the Electromagnetic interaction . . . . . 17 1.2.2 Electroweak interactions . . . . . . . . . . . . . . . . . . . . 19 1.2.3 Strong interaction . . . . . . . . . . . . . . . . . . . . . . . . 20 1.3 Spontaneous Symmetry Breaking and the Higgs Boson . . . . . . . 21 1.3.1 Spontaneous symmetry breaking: the Higgs mechanism . . . 21 1.3.2 Giving a mass to the Fermions . . . . . . . . . . . . . . . . . 23 1.3.3 Discovery of the Higgs Boson . . . . . . . . . . . . . . . . . 24 1.4 The Top Quark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.4.1 Properties of the top quark . . . . . . . . . . . . . . . . . . 25 1.4.2 Electroweak couplings of the top quark . . . . . . . . . . . . 26 1.5 Open Questions in Particle Physics . . . . . . . . . . . . . . . . . . 27

2 The International Linear Collider 31 2.1 Presentation and Motivation of the ILC . . . . . . . . . . . . . . . . 31 2.2 Physics at the International Linear Collider . . . . . . . . . . . . . 33 2.3 The Accelerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2.3.1 The Electron Source . . . . . . . . . . . . . . . . . . . . . . 38 2.3.2 The Positron Source . . . . . . . . . . . . . . . . . . . . . . 38 2.3.3 The Damping Rings . . . . . . . . . . . . . . . . . . . . . . 38 2.3.4 The Main Linac . . . . . . . . . . . . . . . . . . . . . . . . . 39 2.3.5 The Beam Delivery System . . . . . . . . . . . . . . . . . . 39

3 The International Large Detector 41 3.1 Presentation of the ILD . . . . . . . . . . . . . . . . . . . . . . . . 41 3.2 The Particle Flow Algorithm . . . . . . . . . . . . . . . . . . . . . . 44 3.3 The Tracking System of the ILD . . . . . . . . . . . . . . . . . . . . 46 3.3.1 The Vertex Detector . . . . . . . . . . . . . . . . . . . . . . 46 3.3.2 The Silicon Tracking . . . . . . . . . . . . . . . . . . . . . . 47 3.3.3 The Time Projection Chamber . . . . . . . . . . . . . . . . 47 3.4 The Calorimeter System of the ILD . . . . . . . . . . . . . . . . . . 48 3.4.1 The Electromagnetic Calorimeter . . . . . . . . . . . . . . . 48 3.4.2 The Hadronic Calorimeter . . . . . . . . . . . . . . . . . . . 49 3.5 The Outer Part of the ILD . . . . . . . . . . . . . . . . . . . . . . . 49

4 The Physics Prototype of the SiW-ECAL 55 4.1 Presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.2 Design of the SiW-ECAL Physics Prototype . . . . . . . . . . . . . 55 4.3 Calibration and Results . . . . . . . . . . . . . . . . . . . . . . . . 57 4.3.1 The MIP Calibration Algorithm . . . . . . . . . . . . . . . . 58 4.3.2 Response of the Physics Prototype to Electrons . . . . . . . 59

7 Analysis of the Semi-Leptonic Channel of tt¯ Events 105 7.1 Lepton Finder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 7.2 γγ → hadrons Background . . . . . . . . . . . . . . . . . . . . . . . 107 7.3 B-tagging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 7.3.1 The LCFIPlus Package . . . . . . . . . . . . . . . . . . . . . 108 7.3.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 7.4 Top Reconstruction and Background Rejection . . . . . . . . . . . . 110 7.5 The Forward Backward Asymmetry . . . . . . . . . . . . . . . . . . 114 7.5.1 The χ2 Method . . . . . . . . . . . . . . . . . . . . . . . . . 116 7.5.2 The B Charge Method . . . . . . . . . . . . . . . . . . . . . 116 7.6 The Helicity Angle Distribution . . . . . . . . . . . . . . . . . . . . 121

8 Reachable Accuracies on the Top Quark Electroweak Couplings 123 8.1 The Statistical Errors . . . . . . . . . . . . . . . . . . . . . . . . . . 123 8.1.1 The Cross Section . . . . . . . . . . . . . . . . . . . . . . . . 123 8.1.2 The Forward Backward Asymmetry . . . . . . . . . . . . . . 124 8.1.3 The Helicity Angle Distribution . . . . . . . . . . . . . . . . 124 8.2 The Systematic and Theory Errors . . . . . . . . . . . . . . . . . . 125 8.2.1 The Theory Aspects . . . . . . . . . . . . . . . . . . . . . . 126 8.3 Precision of Form Factors . . . . . . . . . . . . . . . . . . . . . . . 127 [1] Particle Physics, third edition B.R. Martin and G. Shaw, ISBN 978-0-470-03294-7.

[11] Broken Symmetries, Massless Particles and Gauge Fields P.W. Higgs, Phys. Lett. 12:132, 1964.

[43] JRA3 electromagnetic calorimeter technical design report M. Anduze, D. Bailey, R. Cornat, P. Cornebise, A. Falou, J. Fleury, J. Giraud, M. Goodrick, D. Grondin, B. Hommels, R. Poeschl, and R. Thompson, Technical Report EUDET-Report-2009-01, EUDET, 2009.

[91] A precise determination of top quark electro-weak couplings at the ILC operating at 500 GeV M.S. Amjad, M. Boronat, T. Frisson, I.Garcia Garcia, R. Po¨schl, E. Ros, F. Richard, J. Rou¨en´e, P.Ruiz Femenia, M. Vos, 2013, arXiv:1307.8102, Publication in progress.

[92] Snowmass 2013 Top quark working group report K. Agashe et al., 2013, arXiv:hep-ph/1311.2028.

[93] Top quark physics: Theoretical aspects W. Bernreuther, P. Igo-Kemenes, M. Jezabek, J. H. Kuhn, B. Lampe, O. Nacht- mann, P. Overmann and T. Schroder et al., http://inspirehep. net/record/325522?ln=en.

[94] CP Nonconservation in Top Quark Production by (Un) Polarized e+e− and γγ Collisions W. Bernreuther, A. Brandenburg, and P. Overmann, arxiv:hep-ph/9602.273.