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Quantum field theory analog effects in nonlinear photonic waveguides
Published in Kuppuswamy Porsezian, Ramanathan Ganapathy, Odyssey of Light in Nonlinear Optical Fibers, 2017
Andrea Marini, Fabio Biancalana
In recent years, theoretical and experimental investigations of neutrino oscillations have received considerable interest, as the observation of this phenomenon implies that neutrinos have small but finite masses. Neutrino oscillations ensue from a mixture between the flavor and mass eigenstates, since the three neutrino states weakly interacting with charged leptons are superpositions of three states with definite mass. In the early universe and in collapsing supernova stars, the density of neutrinos is so large that they strongly interact with each other, many body interactions become important and neutrino oscillations feedback on themselves [50–53]. In turn, peculiar effects like coherence in collective neutrino oscillations and suppression of self-induced flavor conversion occur in supernova explosions [54,55].
Neutrinos
Published in K Grotz, H V Klapdor, S S Wilson, The Weak Interaction in Nuclear, Particle and Astrophysics, 2020
K Grotz, H V Klapdor, S S Wilson
Here the |vi⟩ are the eigenstates of the mass matrix (mass states) with corresponding masses mi, and U is a unitary matrix. The number of mixing flavours is n. The fact that mass eigenstates and flavour states are not identical leads to the phenomenon of neutrino oscillations. Consider a stationary case, and assume that electron neutrinos are continuously emitted with a defined energy E from a ve source at point x→=0. The neutrino state |v(x)⟩ created in this way is a superposition of plane waves of the various mass components |vi⟩: () |ν(x)〉=e-iEt∑iUei|νi〉e+ip→,x→
From First Tritium Operation of the Karlsruhe Tritium Neutrino Experiment Toward Precise Determination of the Neutrino Mass
Published in Fusion Science and Technology, 2020
Magnus Schlösser, KATRIN Collaboration
Neutrino oscillation experiments have conclusively demonstrated that neutrinos have a nonvanishing mass.1–3 However, the results of these types of experiments provide information only on the differences of the squared mass eigenvalues (). Therefore, the absolute neutrino mass scale needs to be determined by other approaches. The three complementary paths are (1) cosmological observations (see data from Ref. 4), (2) neutrinoless double beta decay searches,5–7 and (3) kinematic measurements by utilizing beta decay8,9 or electron capture.10,11 One feature of direct measurements is that no prior assumptions of the neutrino nature or mass model are needed to determine the neutrino mass. Close to the kinematic end point, the neutrino mass manifests itself as a distortion in the spectral shape.12 Tritium is one of the most suitable nuclei because of its low end-point energy, superallowed decay, and simple atomic structure.