# Direct measurement of the top-quark width with the ATLAS experiment

Murillo Quijada , Javier Alberto (2015). Direct measurement of the top-quark width with the ATLAS experiment. University of Birmingham. Ph.D.

 Preview
PDF - Accepted Version

## Abstract

In this thesis a measurement of the total decay width of the top quark, Г$$_{top}$$ is presented using selected semi-leptonic $${t¯t}$$ event candidates, recorded from protonproton collisions at a centre-of-mass energy of $$\sqrt{s}$$ = 8 TeV with the ATLAS experiment at CERN in Geneva, Switzerland. The total recorded integrated luminosity that was used for this measurement equals to $$\int$$Ldt = 20.3 fb$$^{−1}$$. The analysis includes the two event channels: $$e$$ + jets and $$μ$$ + jets. The reconstruction of the $${t¯t}$$ system is achieved by using a per-event $$X$$2 minimisation technique. Official Monte Carlo samples have been used to simulate the t¯t signal and background contributions in order to perform simulated experiments to obtain the statistical and systematic uncertainties.
The results obtained from the measurement of the top parameter are: Г$$_{top}$$ = 1.65 GeV for the $$μ$$ + jets channel and Г$$_{top}$$ = 0.81 GeV for the $$e$$ + jets channel. The upper limits obtained from the measured values and the analysis total uncertainties are: Г$$_{top}$$ < 4.60 GeV at 68 % C.L. and Г$$_{top}$$ < 7.16 GeV at 95 % C.L. for the $$μ$$ + jets channel, and Г$$_{top}$$ < 4.40 GeV at 68 % C.L. and Г$$_{top}$$ < 7.51 GeV at 95 % C.L. for the $$e$$ + jets channel. These results are consistent with the expected SM value
Г$$_{top}$$ ≈ 1.33 GeV.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Supervisor(s):
Supervisor(s)EmailORCID
Wilson, John A.UNSPECIFIEDUNSPECIFIED
Licence:
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Physics and Astronomy
Funders: Other
Other Funders: Consejo Nacional de Ciencia y Tecnología, Mexico
Subjects: Q Science > QC Physics
URI: http://etheses.bham.ac.uk/id/eprint/6186

### Actions

 Request a Correction View Item