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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

We discuss neutrino masses and mixing in the context of seesaw type I models with three right-handed Majorana neutrinos and an approximately diagonal Dirac sector. This ansatz is motivated by the idea that the flavor structure in the…

High Energy Physics - Phenomenology · Physics 2014-06-25 Heinrich Päs , Erik Schumacher

Motivated by the fact that the Dirac phase in the PMNS matrix is the only CP-violating parameter in the leptonic sector that can be measured in neutrino oscillation experiments, we examine the possibility that it is the dominant source of…

High Energy Physics - Phenomenology · Physics 2018-06-11 Matthew J. Dolan , Tomasz P. Dutka , Raymond R. Volkas

The relation between leptogenesis and CP violation at low energies is analyzed in detail in the framework of the minimal seesaw mechanism. Working, without loss of generality, in a weak basis where both the charged lepton and the…

High Energy Physics - Phenomenology · Physics 2008-11-26 G. C. Branco , R. Gonzalez Felipe , F. R. Joaquim , I. Masina , M. N. Rebelo , C. A. Savoy

Using the density matrix equations (DME) for high scale leptogenesis based on the type I seesaw mechanism, in which the CP violation (CPV) is provided by the low-energy Dirac or/and Majorana phases of the neutrino mixing (PMNS) matrix, we…

High Energy Physics - Phenomenology · Physics 2021-11-23 A. Granelli , K. Moffat , S. T. Petcov

We consider a type-I seesaw framework with a flavour symmetry from the series of non-abelian groups $\Delta (3 n^2)$ and $\Delta (6 n^2)$ and a CP symmetry. Breaking these symmetries non-trivially results in the right-handed neutrinos being…

High Energy Physics - Phenomenology · Physics 2022-12-20 Marco Drewes , Yannis Georis , Claudia Hagedorn , Juraj Klarić

We discuss symmetries and scenarios leading to quasi-degenerate neutrinos in type-I seesaw models. The existence of degeneracy in the present approach is not linked to any specific structure for the Dirac neutrino Yukawa coupling matrix…

High Energy Physics - Phenomenology · Physics 2010-11-30 Anjan S. Joshipura , Ketan M. Patel , Sudhir K. Vempati

We study the minimal seesaw model, where two right-handed Majorana neutrinos are introduced, focusing on the CP violating phase. In addition, we take the trimaximal mixing pattern for the neutrino flavor where the charged lepton mass matrix…

High Energy Physics - Phenomenology · Physics 2018-01-17 Yusuke Shimizu , Kenta Takagi , Morimitsu Tanimoto

We consider a supersymmetric SU(4)$_c \times$SU(2)$_L \times$SU(2)$_R$ model with a minimal number of Higgs multiplets and Dirac and Majorana $CP$-violating phases in the neutrino flavor mixing matrix. The model incorporates the charged…

High Energy Physics - Phenomenology · Physics 2018-09-12 Nobuchika Okada , Qaisar Shafi

We explore generic features of the leptonic CP violation in the framework of the seesaw type I mechanism with similarity of the Dirac lepton and quarks mass matrices $m_D$. For this, we elaborate on the standard parametrization conditions…

High Energy Physics - Phenomenology · Physics 2014-05-30 Basudeb Dasgupta , Alexei Yu. Smirnov

The observed neutrino oscillations and baryon asymmetry, unexplained by the Standard Model (SM), can both be accounted for by extending the SM to include Majorana right-handed neutrinos (RHNs). Tiny neutrino masses naturally arise through…

High Energy Physics - Phenomenology · Physics 2025-06-26 Nobuchika Okada , Digesh Raut

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

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 a study of resonant leptogenesis in a radiative seesaw model. We consider the case where two quasi-degenerate right-handed neutrinos realize resonant leptogenesis, and the CP violation necessary to achieve leptogenesis occurs…

High Energy Physics - Phenomenology · Physics 2023-01-11 Bikash Thapa , Ng. K. Francis

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

We propose a novel mechanism in which leptonic CP-violating phases are generated dynamically through the radiative breaking of non-invertible selection rules. In this framework, tree-level mass matrices, initially constrained by a CP-like…

High Energy Physics - Phenomenology · Physics 2026-04-07 Hiroshi Okada , Hajime Otsuka

We perform a thermal unflavored leptogenesis analysis on minimal left-right symmetric models with discrete left-right symmetry identified as generalized parity or charge conjugation. When left-right symmetry is unbroken in the lepton Yukawa…

High Energy Physics - Phenomenology · Physics 2023-02-24 Xinyi Zhang , Jiang-Hao Yu , Bo-Qiang Ma

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

We discuss the correlation between the CP violating Dirac phase of the lepton mixing matrix and the cosmological baryon asymmetry based on the leptogenesis in the minimal seesaw model with two right-handed Majorana neutrinos and the…

High Energy Physics - Phenomenology · Physics 2018-02-01 Yusuke Shimizu , Kenta Takagi , Morimitsu Tanimoto

It was commonly thought that the observation of low energy leptonic CP-violating phases would not automatically imply the existence of a baryon asymmetry in the leptogenesis scenario. This conclusion does not generically hold when the issue…

High Energy Physics - Phenomenology · Physics 2008-11-26 S. Pascoli , S. T. Petcov , A. Riotto