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Neutrinos in Cosmology and Particle Physics

Wu, Jun (2012) Neutrinos in Cosmology and Particle Physics. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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This thesis discusses two independent research topics. We first study keV sterile neutrinos as a Warm Dark Matter (WDM) candidate, focusing on their production at temperatures of the electroweak scale and the linear structure growth of WDM particles with arbitrary
distribution functions and masses of keV scale. At temperatures of the electroweak scale, the medium effect modifies the mixing angle between sterile and active neutrinos, introducing two narrow Mikheev-Smirnov-Wolfenstein (MSW) resonances that break adiabaticity and
enhance the non-thermal production of sterile neutrinos at small momenta. One of the two MSW resonances is in the absence of a lepton asymmetry and occurs only at temperatures around the electroweak scale. By solving the linearized collision-less Boltzmann equation, we obtain a semi-analytical expression of the matter power spectrum for WDM particles with arbitrary distributions agreeing within a few percent error with results from Boltzmann codes. This matter power spectrum depends on the horizon size at matter-radiation equality and the free streaming wave vector kfs, function of mass and distribution of WDM particles. We discover WDM acoustic oscillations at small scales about k>=2k_fs and an Integrated Sachs-Wolfe (ISW) effect in the Radiation Dominant (RD) era which enhances the matter
power spectrum for k<=k_fs. A quasi-degeneracy between the mass and distribution function of WDM on the matter power spectrum is identified, suggesting an inherent ambiguity of
Lyman-alpha analysis to constrain WDM parameters. Secondly, based on the observation that neutrinos produced from decay via the charge current interaction are entangled with the
corresponding charged leptons, we re-investigate the theory of neutrino oscillations with the focus of the dynamics of the entangled state. We study the dynamics of entanglement and dis-entanglement explicitly in time, which leads to non-conventional expressions for neutrino oscillation amplitudes and probabilities suggesting possible corrections for short baseline neutrino oscillation experiments. By applying this method to the GSI anomaly, we
unambiguously show that the GSI anomaly is not a consequence of neutrino oscillations.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Wu, Jun
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairBoyanovsky, Danielboyan@pitt.eduBOYAN
Committee MemberHolman, Richard
Committee MemberKosowsky, Authurkosowsky+@pitt.eduKOSOWSKY
Committee MemberLeibovich, Adamakl2+@pitt.eduAKL2
Committee MemberNaples, Donnadnaples@pitt.eduDNAPLES
Committee MemberZentner, Andrewzentner+@pitt.eduZENTNER
Date: 1 February 2012
Date Type: Publication
Defense Date: 12 October 2011
Approval Date: 1 February 2012
Submission Date: 17 November 2011
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 244
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: sterile neutrinos, Warm Dark Matter, neutrino oscillations, entanglement
Date Deposited: 01 Feb 2012 15:55
Last Modified: 15 Nov 2016 13:55


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