Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1222 Searches for a Charged Higgs Boson in ATLAS and Development of Novel Technology for Future Particle Detector Systems DANIEL PELIKAN ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-554-9153-6 UPPSALA urn:nbn:se:uu:diva-242491 2015 Dissertation presented at Uppsala University to be publicly examined in Polhemssalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, Friday, 20 March 2015 at 10:00 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Prof. Dr. Fabrizio Palla (Istituto Nazionale di Fisica Nucleare (INFN) Pisa). Abstract Pelikan, D. 2015. Searches for a Charged Higgs Boson in ATLAS and Development of Novel Technology for Future Particle Detector Systems. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1222. 119 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9153-6. The discovery of a charged Higgs boson (H±) would be a clear indication for physics beyond the Standard Model. This thesis describes searches for charged Higgs bosons with the ATLAS experiment at CERN’s Large Hadron Collider (LHC). The first data collected during the LHC Run 1 is analysed, searching for a light charged Higgs boson (mH±<mtop), which decays predominantly into a tau-lepton and a neutrino. Different final states with one or two leptons (electrons or muons), as well as leptonically or hadronically decaying taus, are studied, and exclusion limits are set. The background arising from misidentified non-prompt electrons and muons was estimated from data. This so-called "Matrix Method'' exploits the difference in the lepton identification between real, prompt, and misidentified or non-prompt electrons and muons. The Matrix Method is used in all charged Higgs boson searches in this thesis. In 2024 the LHC will be upgraded into a High Luminosity LHC (HL-LHC). The ATLAS detector is expected to collect around 300 fb-1 of collision data until 2022, whereas the HL- LHC will deliver about 250-300 fb-1 of data per year. This will increase the mean number of interactions per bunch crossing, resulting in larger particle fluxes. This puts challenging requirements on the electronics. In order to keep trigger and data rates at manageable levels, new trigger concepts require more intelligence at early stage which possibly results in more cables and connectors, inside the detector which lead to degraded performance of the detector system. This thesis presents new concepts using wireless technology at 60 GHz, in order add more data links inside the detector system without adding much material. Patch antennas have been developed, operating at 60 GHz. Manufacture methods have been investigated, and the fabrication tolerances and bandwidth of these antennas have been studied. Also, concepts of using passive repeaters have been investigated, to make the 60 GHz signal pass boundaries. These repeaters can be used to connect intelligence inside the detector, but also for reading out data from the whole detector radially. Keywords: Charged Higgs boson, Matrix Method, ATLAS, 60 GHz, future particle detector Daniel Pelikan, Department of Physics and Astronomy, High Energy Physics, 516, Uppsala University, SE-751 20 Uppsala, Sweden. © Daniel Pelikan 2015 ISSN 1651-6214 ISBN 978-91-554-9153-6 urn:nbn:se:uu:diva-242491 (http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-242491) List of papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. I The ATLAS Collaboration, + Search for charged Higgs bosons decaying√ via H → τν in top quark pair events using pp collision data at s = 7 TeV with the ATLAS detector, JHEP 1206 (2012) 039 II The ATLAS Collaboration, Search for charged Higgs bosons through the violation√ of lepton universality in ttbar events using pp collision data at s = 7 TeV with the ATLAS experiment, JHEP 03 (2013) 076 III The ATLAS Collaboration, Estimation of non-prompt and fake lepton backgrounds in√ final states with top quarks produced in proton-proton collisions at s = 8 TeV with the ATLAS detector, ATLAS-CONF-2014-058 IV Daniel Pelikan, Nils Bingefors, Richard Brenner, Dragos Dancila, Leif Gustafsson, Wireless data transfer with mm-waves for future tracking detectors, 2014 JINST 9 C11008 V Daniel Pelikan, Nils Bingefors, Richard Brenner, Dragos Dancila, Leif Gustafsson, Radial transfer of tracking data with wireless links, PoS(TIPP2014)095 List of papers not included in this thesis: VI The ATLAS Collaboration, Study of discriminating variables for charged Higgs boson searches in tt¯ events with leptons, using 35/pb of data from the ATLAS detector, ATLAS-CONF-2011-018 VII The ATLAS Collaboration, Search for a charged Higgs boson decaying via H+ → τlep + ν in tt¯ events with one or two light√ leptons in the final state using 1.03/fb of pp collision data recorded at s = 7 TeV with the ATLAS detector, ATLAS-CONF-2011-151 VIII The ATLAS Collaboration, ± Search for charged Higgs bosons decaying√ via H → τν in tt¯ events using 4.6 f b−1 of collision data at s = 7 TeV with the ATLAS detector, ATLAS-CONF-2012-011 IX Daniel Pelikan, Search for charged Higgs bosons in ATLAS, EPJ Web of Conferences 28, 12057 (2012) Hadron Collider Physics Symposium (HCP) 2011 Reprints were made with permission from the publishers. Contents 1 Introduction .................................................................................................. 9 2 Theoretical background ............................................................................. 11 2.1 The Standard Model of particle physics ....................................... 11 2.1.1 The particles of the Standard Model .............................. 11 2.1.2 The Higgs mechanism ..................................................... 14 2.2 Beyond the Standard Model (BSM) physics ................................ 16 2.2.1 Phenomena not explained by the Standard Model ........ 16 2.2.2 Supersymmetry ................................................................ 17 2.2.3 The charged Higgs bosons .............................................. 20 2.2.4 Production and decay of charged Higgs bosons ............ 22 3 The CERN laboratory ................................................................................ 34 3.1 Scientific achievements made by CERN ...................................... 34 3.2 The accelerator infrastructure ........................................................ 34 3.2.1 Linac-2 ............................................................................. 36 3.2.2 Linac-3 ............................................................................. 36 3.2.3 Linac-4 ............................................................................. 36 3.2.4 Proton Synchrotron Booster (PSB) ................................ 36 3.2.5 Proton Synchrotron (PS) ................................................. 36 3.2.6 Super Proton Synchrotron (SPS) .................................... 36 3.3 The Large Hadron Collider (LHC) ............................................... 37 3.4 The four experiments at the LHC .................................................. 38 4 The ATLAS detector system ..................................................................... 39 4.1 Conventions .................................................................................... 39 4.2 The inner detector ......................................................................... 41 4.3 The calorimeters ............................................................................. 42 4.4 The muon spectrometer ................................................................. 44 4.5 The trigger system .......................................................................... 46 5 Physics analysis in ATLAS ....................................................................... 47 5.1 Charged Higgs boson searches in ATLAS ................................... 47 5.1.1 Measurement of discriminating variables for charged Higgs boson searches ...................................................... 47 5.1.2 Charged Higgs boson searches in the single- and di-lepton channels ............................................................ 48 5.1.3 Combination of the most sensitive channels for charged Higgs boson searches ........................................ 49 5.1.4 Charged Higgs boson searches through the violation of lepton universality ........................................................... 50 5.1.5 Charged Higgs boson searches with the 2012 dataset ... 51 5.2 The Matrix Method ........................................................................ 51 5.2.1 The Matrix Method related to top quark and charged Higgs boson physics in ATLAS ...................................... 52 5.2.2 Physics analyses .............................................................. 53 6 Future data readout challenges at LHC .................................................... 58 6.1 Introduction .................................................................................... 58 6.2 Wireless technology in future detector systems ........................... 59 6.2.1 Choice of the frequency band for wireless data links ... 60 6.2.2 Connection concept ......................................................... 61 6.2.3 Requirements on the antenna system ............................. 62 6.3 Radiation damage to antenna substrate ......................................... 63 6.3.1 Effect