Measurement of the Top Quark Mass in the All-Hadronic Channel at Proton Antiproton Collisions at $$\sqrt{s}$$ = 1.96 TeV with CDF II
- Univ. of Bologna (Italy)
We report a measurement of the top quark mass in the all-hadronic channel with the upgraded Collider Detector at Fermilab using an integrated luminosity of 1.02 $$fb^{-1}$$ . Top quarks are produced mostly in pairs at the Tevatron Collider; they subsequently decay almost 100% of the time in a W boson and a b quark each. Final states are classified according to the decays of the W bosons. Here we study only those events in which both W's decay into quark pairs. This channel has the advantage of a large branching ratio and of being fully reconstructed. On the other hand the signal is overwhelmed by a background which surpasses it by three orders of magnitude even after the requirement of a specific trigger. A neural network is thus used to discriminate signal from background events in order to achieve a good signal over background ratio. We look for a variable which is strongly correlated with the top quark mass, and compare the corresponding distribution in the data to signal and background templates in order to measure the top quark mass. Here is an outline of the following of this work: Chapter 1 presents an introduction to the path that lead to the formalization of the Standard Model of fundamental interactions. We discuss in Chapter 2 the need for a 6th quark in the Standard Model, the phenomenology of the top quark and a summary of the current experimental knowledge of its properties, and motivate the need for a precise measurement of its mass. In Chapter 3 we describe the experimental apparatus needed to produce the top quarks, i.e. the Tevatron Collider, and the detector which collects the data analyzed in this work, CDF II. Chapter 4 describes how CDF II interprets the output from the various subdetectors and translate them into the physics objects which are needed for the measurement. In Chapter 5 we present how we overcome the problem of the huge background which overwhelms the top production by using for the first time in this channel a neural network approach to select the candidate events. Finally, in Chapter 6 we present and discuss the technique used to extract the top quark mass measurement, how we control this technique, evaluate the systematics uncertainties, and finally apply the method to the data to obtain the top quark mass measurement.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1369258
- Report Number(s):
- FERMILAB-THESIS-2007-88; 1123195
- Country of Publication:
- United States
- Language:
- English
Similar Records
Measurement of the t$\bar{t}$ production cross section in the ET+jets channel at CDF
Measurement of the top pair production cross section at CDF using neural networks