87 research outputs found
Adiabatic & non-adiabatic perturbation theory for coherence vector description of neutrino oscillations
The standard wave function approach for the treatment of neutrino
oscillations fails in situations where quantum ensembles at a finite
temperature with or without an interacting background plasma are encountered.
As a first step to treat such phenomena in a novel way, we propose a unified
approach to both adiabatic and non-adiabatic two-flavor oscillations in
neutrino ensembles with finite temperature and generic (e.g. matter)
potentials. Neglecting effects of ensemble decoherence for now we study the
evolution of a neutrino ensemble governed by the associated Quantum Kinetic
Equations, which apply to systems with finite temperature. The Quantum Kinetic
Equations are solved formally using the Magnus expansion and it is shown that a
convenient choice of the quantum mechanical picture (e.g. the interaction
picture) reveals suitable parameters to characterize the physics of the
underlying system (e.g. an effective oscillation length). It is understood that
this method also provides a promising starting point for the treatment of the
more general case in which decoherence is taken into account.Comment: 14 page
Neutrinoless Double Beta Decay
We review the potential to probe new physics with neutrinoless double beta
decay . Both the standard long-range light neutrino
mechanism as well as short-range mechanisms mediated by heavy particles are
discussed. We also stress aspects of the connection to lepton number violation
at colliders and the implications for baryogenesis.Comment: Review prepared for the NJP focus issue on "Neutrino Physics". 23
pages, 10 figure
Sterile Neutrino Shortcuts in Asymmetrically Warped Extra Dimensions
Light sterile neutrinos are a popular extension of the Standard Model and are
being discussed as a possible explanation for various neutrino oscillation
anomalies, including the LSND, MiniBooNE, Reactor and Gallium anomalies. In
order to avoid inconsistencies with constraints derived from disappearance
experiments and cosmology, altered dispersion relations - which may originate
from extra dimensions - have been proposed as a possible solution, dubbed as
"neutrino shortcuts in the extra dimension". In this paper we develop a
neutrino mass model with an asymmetrically warped extra dimension and two
additional gauge singlet neutrinos, one being responsible for neutrino mass
generation, while the other one is allowed to propagate in the extra dimension,
giving rise to the desired change of the dispersion relation on the brane. By
compactifying the extra-dimensional theory on an orbifold,
deriving the shape of the Kaluza-Klein tower and identifying the effective
sterile neutrino dispersion relation on the brane, we can demonstrate that the
earlier, phenomenological models are recovered as the 4-dimensional effective
field theory limit of the model discussed here.Comment: 15 page
Leptonic Flavor Structure in the Brane Shifted Extra Dimensional Seesaw Mechanism
We discuss the leptonic flavor structure generated by a brane shifted extra
dimensional seesaw model with a single right handed neutrino in the bulk. In
contrast to previous works, no unitarity approximation for the
submatrix has been employed. This allows to study phenomenological signatures
such as lepton flavor violating decays. A strong prediction of the model,
assuming CP conservation, are the ratios of flavor violating charged lepton
decay and Z decay branching ratios which are correlated with the neutrino
mixing angles and the neutrino mass hierarchy. Furthermore, it is possible to
obtain branching ratios for close to the
experimental bounds even with Yukawa couplings of order one.Comment: 13 pages plus appendix and references, 4 figures. v2: version
accepted by EPJ
- …