رسالة جامعية
Search for new particles decaying to a top quark pair with the CMS experiment
| العنوان: | Search for new particles decaying to a top quark pair with the CMS experiment |
|---|---|
| المؤلفون: | Steggemann, Jan |
| المساهمون: | Erdmann, Martin |
| المصدر: | Aachen : Publikationsserver der RWTH Aachen University V, 193 S. : Ill., graph. Darst. (2012). = Aachen, Techn. Hochsch., Diss., 2012 |
| بيانات النشر: | Publikationsserver der RWTH Aachen University |
| سنة النشر: | 2012 |
| المجموعة: | RWTH Aachen University: RWTH Publications |
| مصطلحات موضوعية: | info:eu-repo/classification/ddc/530, t-Quark, LHC, CMS-Detektor, Standardmodell |
| جغرافية الموضوع: | DE |
| الوصف: | In 2011, the Compact Muon Solenoid (CMS) detector recorded 5 fb^{-1} of pp collision data delivered by the Large Hadron Collider at a centre-of-mass energy of 7 TeV. The large number of events from ttbar production allows to precisely analyse the production and decay of ttbar pairs in an unprecedented energy regime. In this thesis, the invariant mass distribution of the reconstructed ttbar system (m(ttbar)) is measured and compared to predictions according to the Standard Model of particle physics. With the help of the measured m(ttbar) distribution, searches for new particles decaying to a tbar pair are performed. Such new particles would appear as resonant contributions in addition to the non-resonant m(ttbar) distributions from Standard Model background processes. The focus of the data analysis extends from invariant top quark pair masses near the production threshold of m(ttbar) ~ 2 m(top) to the region of m(ttbar) ~ 2 TeV. The analysis is based on the final state of the ttbar system with one charged lepton, i.e. either a muon or an electron, a neutrino, and four jets, of which two are b quark jets. A full kinematic reconstruction of these events is performed with a chi2 method. The selected events are divided in 8 subsamples according to the number of selected jets, the number of jets that are identified as b quark jets, and the lepton flavour (muon or electron). This categorisation takes advantage of the different signal-to-background ratios in the different event categories and improves the statistical sensitivity of the search. The measured m(ttbar) distributions in all 8 subsamples show good agreement with the expectation from the background processes that are simulated according to the Standard Model. The compatibility is tested by performing a background-only fit including all relevant systematic uncertainties. Stringent limits are set on the production cross section for new particles that are predicted by a number of models for new physics. The considered masses extend from 0.5 TeV to 2 TeV, with the ... |
| نوع الوثيقة: | doctoral or postdoctoral thesis |
| اللغة: | English |
| العلاقة: | info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-43368; https://publications.rwth-aachen.de/record/197567Test; https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-143422%22Test |
| الإتاحة: | https://publications.rwth-aachen.de/record/197567Test https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-143422%22Test |
| حقوق: | info:eu-repo/semantics/openAccess |
| رقم الانضمام: | edsbas.2F32D960 |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |