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In the type-I seesaw mechanism the Casas-Ibarra (CI) parametrization provides a convenient description of the Dirac neutrino mass matrix in terms of the light and heavy Majorana neutrino masses, the lepton flavor mixing matrix $U$ and an…

High Energy Physics - Phenomenology · Physics 2020-05-20 Zhi-zhong Xing , Di Zhang

The parameterisation proposed by Casas and Ibarra in the year 2001 have shown promising role in the extraction of neutrino Yukawa coupling which is a basic ingredient of the seesaw mechanism generating neutrino mass. We pay special…

High Energy Physics - Phenomenology · Physics 2023-05-23 Ananya Mukherjee , Nimmala Narendra

The Casas-Ibarra (CI) parametrization of the Yukawa coupling matrix of Majorana neutrinos is generalized by considering the exact seesaw relation and including non-unitarity of the $3 \times 3$ Pontecorvo-Maki-Nakagawa-Sakata (PMNS) flavor…

High Energy Physics - Phenomenology · Physics 2024-10-16 Zhi-zhong Xing

The origin of tiny neutrino masses and the baryon number asymmetry of the Universe are naturally interpreted by the canonical seesaw and leptogenesis mechanisms, in which there are the heavy Majorana neutrino mass matrix $M_{\rm R}$, the…

High Energy Physics - Phenomenology · Physics 2014-06-06 Yikun Wang , Zhi-zhong Xing

Both neutrinoless double beta decay and leptogenesis require neutrinos to be Majorana fermions. A relation between these two phenomena can be derived once the mechanism of neutrino mass generation is specified. We first derive the…

High Energy Physics - Phenomenology · Physics 2021-02-03 Nimmala Narendra , Narendra Sahu , S. Uma Sankar

We consider leptogenesis in a left-right-symmetric seesaw scenario in which neutrino mass generation and leptogenesis are dominated by the type-II seesaw term. Motivated by grand unification, we assume that the neutrino Dirac mass matrix is…

High Energy Physics - Phenomenology · Physics 2021-09-29 Thomas Rink , Werner Rodejohann , Kai Schmitz

We consider the see-saw mechanism for hierarchical Dirac and Majorana neutrino mass matrices m_D and M_R, including the CP violating phases. Simple arguments about the structure of the neutrino mass matrix and the requirement of successful…

High Energy Physics - Phenomenology · Physics 2011-07-19 Werner Rodejohann

Effects of the lightest neutrino mass in "flavoured" leptogenesis when the CP-violation necessary for the generation of the baryon asymmetry of the Universe is due exclusively to the Dirac and/or Majorana phases in the neutrino mixing…

High Energy Physics - Phenomenology · Physics 2009-07-22 E. Molinaro , S. T. Petcov , T. Shindou , Y. Takanishi

We study the exactly degenerate case for three lefthanded Majorana neutrinos building a general parametrization for the leptonic mixing matrix characterized by two angles and one CP violating phase and identify a weak-basis invariant…

High Energy Physics - Phenomenology · Physics 2017-08-23 G. C. Branco , M. N. Rebelo , J. I. Silva-Marcos

We study leptonic CP violation from a new perspective. For Majorana neutrinos, a new parametrization for leptonic mixing of the form $V=O_{23} O_{12} K_{a}^{i}\cdot O$ reveals interesting aspects that are less clear in the standard…

High Energy Physics - Phenomenology · Physics 2015-07-29 David Emmanuel-Costa , Nuno Rosa Agostinho , J. I. Silva-Marcos , Daniel Wegman

In this letter, we perform a chiral perturbative analysis by singular values $m_{Di}$ of the Dirac mass matrix $m_{D}$ for the type-I seesaw mechanism. In the basis where $m_{D} = V m_{D}^{\rm diag} U^{\dagger}$ is diagonal, the mass matrix…

High Energy Physics - Phenomenology · Physics 2024-02-15 Masaki J. S. Yang

We propose a minimal $A_4$ flavor symmetric model, assisted by $Z_2 \times Z_3$ symmetry, which can naturally takes care of the appropriate lepton mixing and neutrino masses via Type-I seesaw. It turns out that the framework, originated due…

High Energy Physics - Phenomenology · Physics 2022-01-05 Arghyajit Datta , Biswajit Karmakar , Arunansu Sil

We present a classification of possible parametrizations of the 3x3 lepton flavor mixing matrix in terms of the rotation and phase angles. A particular parametrization, which is most convenient to describe the observables of neutrino…

High Energy Physics - Phenomenology · Physics 2014-11-17 Harald Fritzsch , Zhi-zhong Xing

In the type I + II seesaw formula the mass matrix of light neutrinos m_nu receives contributions from the exchanges of both heavy Majorana neutrinos and SU(2)_L-triplet Higgs bosons. We propose a new parameterization for the Dirac-type…

High Energy Physics - Phenomenology · Physics 2009-01-06 Evgeny Kh. Akhmedov , Werner Rodejohann

In the framework of seesaw mechanism with three neutrino flavors, we propose tentatively an efficient parametrization for the spectra of Dirac and righthanded Majorana neutrino mass matrices in terms of three free parameters. Two of them…

High Energy Physics - Phenomenology · Physics 2007-05-23 W. Krolikowski

Leptogenesis in a left-right symmetric model is investigated for all possible neutrino mass hierarchies. The predictions of the model for low energy parameters as measured in neutrinoless double beta decay and in oscillation experiments are…

High Energy Physics - Phenomenology · Physics 2010-04-05 Werner Rodejohann

We study mixing and CP violation of three left-handed Majorana neutrinos in the limit of exactly degenerate masses, identify the weak-basis invariant relevant for CP violation and show that the leptonic mixing matrix is parametrized only by…

High Energy Physics - Phenomenology · Physics 2009-10-31 G. C. Branco , M. N. Rebelo , J. I. Silva-Marcos

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…

High Energy Physics - Phenomenology · Physics 2009-12-15 Werner Rodejohann

We present an overview of recent progress in the phenomenological study of neutrino masses, lepton flavor mixing and CP violation. We concentrate on the model-independent properties of massive neutrinos, both in vacuum and in matter.…

High Energy Physics - Phenomenology · Physics 2009-11-10 Zhi-zhong Xing

We studied models of leptogenesis where three right-handed Majorana neutrinos are involved and the minimal-extended seesaw mechanism including an additional singlet field produces four light neutrinos. This study shows that the type of mass…

High Energy Physics - Phenomenology · Physics 2022-12-28 Ki-Young Jung , Kim Siyeon
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