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Zhizhong Xing - One of the best experts on this subject based on the ideXlab platform.
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testing unitarity of the 3 3 neutrino Mixing Matrix in an atomic system
International Journal of Modern Physics A, 2020Co-Authors: Guo Yuan Huang, Noboru Sasao, Zhizhong Xing, Motohiko YoshimuraAbstract:Unitarity of the 3 × 3 lepton flavor Mixing Matrix V is unavoidably violated in a seesaw mechanism if its new heavy degrees of freedom are slightly mixed with the active neutrino flavors. We propos...
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towards testing the unitarity of the 3x3 lepton flavor Mixing Matrix in a precision reactor antineutrino oscillation experiment
Physics Letters B, 2013Co-Authors: Zhizhong XingAbstract:The 3 x 3 Maki-Nakagawa-Sakata-Pontecorvo (MNSP) lepton flavor Mixing Matrix may be slightly non-unitary if the three active neutrinos are coupled with sterile neutrinos. We show that it is in principle possible to test whether the relation vertical bar V-e1 vertical bar(2) + vertical bar Ve(2)vertical bar(2) + vertical bar Ve(3)vertical bar(2) = 1 holds or not in a precision reactor antineutrino oscillation experiment, such as the recently proposed Daya Bay II experiment. We explore three categories of non-unitary effects on the 3 x 3 MNSP Matrix: 1) the indirect effect in the (3 + 3) flavor Mixing scenario where the three heavy sterile neutrinos do not take part in neutrino oscillations; 2) the direct effect in the (3 + 1) scenario where the light sterile neutrino can oscillate into the active ones; and 3) the interplay of both of them in the (3 + 1 +2) scenario. We find that both the zero-distance effect and flavor Mixing factors of different oscillation modes can be used to determine or constrain the sum of vertical bar Ve(1)vertical bar(2), vertical bar Ve(2)vertical bar(2) and vertical bar Ve(3)vertical bar(2) and its possible deviation from one, and the active neutrino Mixing angles theta(12) and theta(13) can be cleanly extracted even in the presence of light or heavy sterile neutrinos. Some useful analytical results are obtained for each of the three scenarios. (C) 2012 Elsevier B.V. All rights reserved.
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full parametrization of the 6 x 6 flavor Mixing Matrix in the presence of three light or heavy sterile neutrinos
Physical Review D, 2012Co-Authors: Zhizhong XingAbstract:In addition to three active neutrinos nu(e), nu(mu), and nu(tau), one or more light sterile neutrinos have been conjectured to account for the LSND, MiniBooNE, and reactor antineutrino anomalies (at the sub-eV mass scale) or for warm dark matter in the Universe (at the keV mass scale). Heavy Majorana neutrinos at or above the TeV scale have also been assumed in some seesaw models. Such hypothetical particles can weakly mix with active neutrinos, and thus their existence can be detected at low energies. In the (3 + 3) scenario with three sterile neutrinos we present a full parametrization of the 6 x 6 flavor Mixing Matrix in terms of 15 rotation angles and 15 phase angles. We show that this standard parametrization allows us to clearly describe the salient features of some problems in neutrino phenomenology, such as (a) possible contributions of light sterile neutrinos to the tritium beta decay and neutrinoless double-beta decay, (b) leptonic CP violation and deformed unitarity triangles of the 3 x 3 flavor Mixing Matrix of three active neutrinos, (c) a reconstruction of the 6 x 6 neutrino mass Matrix in the type-(I+II) seesaw mechanism, and (d) flavored and unflavored leptogenesis scenarios in the type-I seesaw mechanism with three heavy Majorana neutrinos.
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reconstruction of the neutrino Mixing Matrix and leptonic unitarity triangles from long baseline neutrino oscillations
Physics Letters B, 2005Co-Authors: Zhizhong Xing, He ZhangAbstract:We derive a new set of sum rules between the neutrino mass and Mixing parameters in vacuum and their effective counterparts in matter. The moduli of nine genuine lepton Mixing Matrix elements can then be calculated in terms of the matter-coffected ones, and the latter can directly be determined from a variety of long-baseline neutrino oscillations. We show that it is possible to reconstruct the leptonic unitarity triangles and CP violation in a similar parametrization-independent way. (c) 2005 Elsevier B.V. All rights reserved.
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implications of the kamland measurement on the lepton flavor Mixing Matrix and the neutrino mass Matrix
Physical Review D, 2003Co-Authors: Wanlei Guo, Zhizhong XingAbstract:We explore some important implications of the KamLAND measurment on the lepton flavor Mixing Matrix V and the neutrino mass Matrix M. The model-independent constraints on nine Matrix elements of V are obtained to a reasonable degree of accuracy. We find that nine two-zero textures of M are compatible with current experimental data, but two of them are only marginally allowed. Instructive predictions are given for the absolute neutrino masses, Majorana phases of CP violation, effective masses of the tritium beta decay, and neutrinoless double beta decay.
Werner Rodejohann - One of the best experts on this subject based on the ideXlab platform.
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symmetrical parametrizations of the lepton Mixing Matrix
Physical Review D, 2011Co-Authors: Werner Rodejohann, J W F ValleAbstract:Advantages of the original symmetrical form of the parametrization of the lepton Mixing Matrix are discussed. It provides a conceptually more transparent description of neutrino oscillations and lepton number violating processes like neutrinoless double beta decay, clarifying the significance of Dirac and Majorana phases. It is also ideal for parametrizing scenarios with light sterile neutrinos.
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non unitary lepton Mixing Matrix leptogenesis and low energy cp violation
EPL, 2009Co-Authors: Werner RodejohannAbstract:It is well known that for unflavored leptogenesis there is in general no connection between low- and high-energy CP violation. We stress that for a non-unitary lepton Mixing Matrix this may not be the case. We give an illustrative example for this connection and show that the non-standard CP phases that are induced by non-unitarity can be responsible for observable effects in neutrino oscillation experiments as well as for the generation of the baryon asymmetry of the Universe. Lepton flavor violation in decays such as τ→μγ can also be induced at an observable level. We also comment on the neutrino mass limits from leptogenesis, which get barely modified in case of a non-unitary Mixing Matrix.
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non unitary lepton Mixing Matrix leptogenesis and low energy cp violation
arXiv: High Energy Physics - Phenomenology, 2009Co-Authors: Werner RodejohannAbstract:It is well-known that for unflavored leptogenesis there is in general no connection between low and high energy CP violation. We stress that for a non-unitary lepton Mixing Matrix this may not be the case. We give an illustrative example for this connection and show that the non-standard CP phases that are induced by non-unitarity can be responsible for observable effects in neutrino oscillation experiments as well as for the generation of the baryon asymmetry of the Universe. Lepton Flavor Violation in decays such as tau -> mu gamma can also be induced at an observable level. We also comment on neutrino mass limits from leptogenesis, which get barely modified in case of a non-unitary Mixing Matrix.
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a parametrization for the neutrino Mixing Matrix
Physical Review D, 2004Co-Authors: Werner RodejohannAbstract:We propose a flexible and model independent parametrization of the neutrino Mixing Matrix, which takes advantage of the fact that there are up to three small quantities in neutrino Mixing phenomenology: (i) the deviation from maximal Mixing of solar neutrinos, (ii) the Mixing Matrix element Ue3 and (iii) the deviation from maximal Mixing of atmospheric neutrinos. It is possible to quantify those three observations with a parameter 0:2, which appears at least linearly in all elements of the Mixing Matrix. Present and future experiments can be used to pin down the power of required to usefully describe the observed phenomenology. Observing that the ratio of the two measured mass squared dierences is roughly 2 allows to further study the structure of the Majorana mass Matrix. We comment on the implications of this parametrization for neutrinoless double beta decay and on the oscillation probabilities in long{baseline experiments.
L Lavoura - One of the best experts on this subject based on the ideXlab platform.
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a model realizing the harrison perkins scott lepton Mixing Matrix
Journal of High Energy Physics, 2006Co-Authors: W Grimus, L LavouraAbstract:We present a supersymmetric model in which the lepton Mixing Matrix U obeys, at the seesaw scale, the Harrison-Perkins-Scott Ansatz — vanishing Ue3, maximal atmospheric neutrino Mixing, and sin 2θ⊙ = 1/3 (θ⊙ is the solar Mixing angle). The model features a permutation symmetry S3 among the three lepton multiplets of each type — left-handed doublets, right-handed charged leptons, and right-handed neutrinos — and among three Higgs doublets and three zero-hypercharge scalar singlets; a fourth right-handed neutrino, a fourth Higgs doublet, and a fourth scalar singlet are invariant under S3. In addition, the model has seven 2 symmetries, out of which six do not commute with S3. Supersymmetry is needed in order to eliminate some quartic terms from the scalar potential, quartic terms which would make impossible to obtain the required vacuum expectation values of the three Higgs doublets and three scalar singlets. The Yukawa couplings to the charged leptons are flavour diagonal, so that flavour-changing neutral Yukawa interactions only arise at loop level.
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a model realizing the harrison perkins scott lepton Mixing Matrix
arXiv: High Energy Physics - Phenomenology, 2005Co-Authors: W Grimus, L LavouraAbstract:We present a supersymmetric model in which the lepton Mixing Matrix $U$ obeys, at the seesaw scale, the Harrison--Perkins--Scott \textit{Ansatz}--vanishing $U_{e3}$, maximal atmospheric neutrino Mixing, and $\sin^2{\theta_\odot} = 1/3$ ($\theta_\odot$ is the solar Mixing angle). The model features a permutation symmetry $S_3$ among the three lepton multiplets of each type--left-handed doublets, right-handed charged leptons, and right-handed neutrinos--and among three Higgs doublets and three zero-hypercharge scalar singlets; a fourth right-handed neutrino, a fourth Higgs doublet, and a fourth scalar singlet are invariant under $S_3$. In addition, the model has seven $\mathbbm{Z}_2$ symmetries, out of which six do not commute with $S_3$. Supersymmetry is needed in order to eliminate some quartic terms from the scalar potential, quartic terms which would make impossible to obtain the required vacuum expectation values of the three Higgs doublets and three scalar singlets. The Yukawa couplings to the charged leptons are flavour diagonal, so that flavour-changing neutral Yukawa interactions only arise at loop level.
J W F Valle - One of the best experts on this subject based on the ideXlab platform.
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symmetrical parametrizations of the lepton Mixing Matrix
Physical Review D, 2011Co-Authors: Werner Rodejohann, J W F ValleAbstract:Advantages of the original symmetrical form of the parametrization of the lepton Mixing Matrix are discussed. It provides a conceptually more transparent description of neutrino oscillations and lepton number violating processes like neutrinoless double beta decay, clarifying the significance of Dirac and Majorana phases. It is also ideal for parametrizing scenarios with light sterile neutrinos.
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underlying a4 symmetry for the neutrino mass Matrix and the quark Mixing Matrix
Physics Letters B, 2003Co-Authors: K S Babu, J W F ValleAbstract:Abstract The discrete non-Abelian symmetry A 4 , valid at some high-energy scale, naturally leads to three degenerate neutrino masses, without spoiling the hierarchy of charged-lepton masses. Realistic neutrino Mixing angles (one of which is necessarily maximal and the other large) are then automatically induced radiatively, and the correct mass splittings may be obtained in the context of softly broken supersymmetry. The quark Mixing Matrix is also calculable in a similar way. The Mixing parameter U e 3 is predicted to be imaginary, leading to maximal CP violation in neutrino oscillations. Neutrinoless double beta decay and τ → μγ should be in the experimentally accessible range.
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underlying a_4 symmetry for the neutrino mass Matrix and the quark Mixing Matrix
arXiv: High Energy Physics - Phenomenology, 2002Co-Authors: K S Babu, J W F ValleAbstract:The discrete non-Abelian symmetry $A_4$, valid at some high-energy scale, naturally leads to degenerate neutrino masses, without spoiling the hierarchy of charged-lepton masses. Realistic neutrino mass splittings and Mixing angles (one of which is necessarily maximal and the other large) are then induced radiatively in the context of softly broken supersymmetry. The quark Mixing Matrix is also calculable in a similar way. The Mixing parameter $U_{e3}$ is predicted to be imaginary, leading to maximal CP violation in neutrino oscillations. Neutrinoless double beta decay and $\tau \to \mu \gamma$ should be in the experimentally accessible range.
W Grimus - One of the best experts on this subject based on the ideXlab platform.
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a model realizing the harrison perkins scott lepton Mixing Matrix
Journal of High Energy Physics, 2006Co-Authors: W Grimus, L LavouraAbstract:We present a supersymmetric model in which the lepton Mixing Matrix U obeys, at the seesaw scale, the Harrison-Perkins-Scott Ansatz — vanishing Ue3, maximal atmospheric neutrino Mixing, and sin 2θ⊙ = 1/3 (θ⊙ is the solar Mixing angle). The model features a permutation symmetry S3 among the three lepton multiplets of each type — left-handed doublets, right-handed charged leptons, and right-handed neutrinos — and among three Higgs doublets and three zero-hypercharge scalar singlets; a fourth right-handed neutrino, a fourth Higgs doublet, and a fourth scalar singlet are invariant under S3. In addition, the model has seven 2 symmetries, out of which six do not commute with S3. Supersymmetry is needed in order to eliminate some quartic terms from the scalar potential, quartic terms which would make impossible to obtain the required vacuum expectation values of the three Higgs doublets and three scalar singlets. The Yukawa couplings to the charged leptons are flavour diagonal, so that flavour-changing neutral Yukawa interactions only arise at loop level.
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a model realizing the harrison perkins scott lepton Mixing Matrix
arXiv: High Energy Physics - Phenomenology, 2005Co-Authors: W Grimus, L LavouraAbstract:We present a supersymmetric model in which the lepton Mixing Matrix $U$ obeys, at the seesaw scale, the Harrison--Perkins--Scott \textit{Ansatz}--vanishing $U_{e3}$, maximal atmospheric neutrino Mixing, and $\sin^2{\theta_\odot} = 1/3$ ($\theta_\odot$ is the solar Mixing angle). The model features a permutation symmetry $S_3$ among the three lepton multiplets of each type--left-handed doublets, right-handed charged leptons, and right-handed neutrinos--and among three Higgs doublets and three zero-hypercharge scalar singlets; a fourth right-handed neutrino, a fourth Higgs doublet, and a fourth scalar singlet are invariant under $S_3$. In addition, the model has seven $\mathbbm{Z}_2$ symmetries, out of which six do not commute with $S_3$. Supersymmetry is needed in order to eliminate some quartic terms from the scalar potential, quartic terms which would make impossible to obtain the required vacuum expectation values of the three Higgs doublets and three scalar singlets. The Yukawa couplings to the charged leptons are flavour diagonal, so that flavour-changing neutral Yukawa interactions only arise at loop level.