Comparison of oscillation parameters measured from $$\nu_\mu$$ and $$\bar{\nu}_\mu$$ disappearance in the NOvA experiment
The NOvA experiment is a neutrino oscillation experiment designed to make precise measurements of \nueD and \nuebarD appearance and \numuD and \numubarD disappearance at long distances and GeV energy scales. Using Fermilab's Neutrinos at the Main Injector (NuMI) beam, the experiment is provided with a highly pure and abundant source of either \numuD or $$\numubar$$. NOvA’s \numuD and \numubarD disappearance measurement is particularly sensitive to constraining the \snD vs.~\dmD space of oscillation parameters. Any difference between \numuD and \numubarD disappearance in vacuum could be an indication of the combination of Charge Conjugation, Parity and Time reversal (CPT) symmetry not being conserved in the neutrino sector or something else beyond our current understanding of physics.\medskip This thesis presents results from two \numuD and \numubarD disappearance analyses, one where \snD and \dmD are assumed to be identical as in the standard three neutrino flavour model, and t he other where the oscillation parameters can differ between neutrinos and antineutrinos. In the later, the core analysis of this thesis, the parameters \snD and \dmD are measured using just the information from neutrinos, and the parameters \snbarD and \dmbarD are measured using just the information from antineutrinos. The results for the mass splitting are $$\Delta m^2_{32}=2.48^{+0.07}_{-0.09} \times 10^{-3}~\rm{eV}^2$$ and $$\Delta\bar{m}^2_{32}=2.55^{+0.12}_{-0.13} \times 10^{-3}~\rm{eV}^2$$. The results for the mixing angle are $$\rm{sin}^2\theta_{23}= 0.51$$ in the range $[0.45, 0.57]$, and two degenerate best fits for $$\rm{sin}^2\bar{\theta}_{23}$$ at 0.41 and 0.61 in the ranges $[0.38, 0.45]$ and $[0.57, 0.64]$ allowed at $$1~\sigma$$. No significant difference between the oscillation parameters measured using \numuD or \numubarD was found. The data analysed in this thesis was collected between 2014 and 2019, for which the NOvA detectors collected an exposure of \potFHC and \potRHC protons-on-target (POT) for the production of the \n! umuD and \numubarD beams respectively. This data is about a quarter and a third of what NOvA is expected to collect in \nuD and \nubarD mode, respectively.
- 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:
- 1579208
- Report Number(s):
- FERMILAB-THESIS-2019-15; oai:inspirehep.net:1769974
- Country of Publication:
- United States
- Language:
- English
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