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We provide a classification of generalized CP symmetries preserved by the neutrino mass matrix according to the number of zero entries in the associated transformation matrix. We determine the corresponding constrained form of the lepton…

High Energy Physics - Phenomenology · Physics 2016-08-10 Peng Chen , Gui-Jun Ding , Felix Gonzalez-Canales , J. W. F. Valle

Assuming a type-I seesaw mechanism for neutrino mass generation and invoking a baryogengesis via leptogenesis scenario, we consider a reasonable hierarchical structure for Dirac neutrino mass matrix, similar to up-type quark mass matrix.…

High Energy Physics - Phenomenology · Physics 2018-11-14 Franco Buccella , Damiano F. G. Fiorillo , Gennaro Miele , Stefano Morisi , Ofelia Pisanti , Pietro Santorelli

We consider a class of models of neutrino mixing with $S_4$ lepton flavour symmetry combined with a generalised CP symmetry, which are broken to residual $Z_2$ and $Z_2 \times H^\nu_{\rm CP}$ symmetries in the charged lepton and neutrino…

High Energy Physics - Phenomenology · Physics 2017-12-07 J. T. Penedo , S. T. Petcov , A. V. Titov

We propose a simple phenomenological model of quarks-leptons mass matrices having fundamentally universal symmetry structure. These mass matrices consist of democratic and semi-democratic mass matrix terms commonly to the neutrino and the…

High Energy Physics - Phenomenology · Physics 2016-01-20 Hiroyuki Nishiura , Takeshi Fukuyama

We discuss the minimal seesaw model for the Dirac CP violating phase of the lepton mixing matrix. We introduce two right-handed Majorana neutrinos and obtain several textures of the tri-maximal lepton mixing matrices. Moreover, we discuss…

High Energy Physics - Phenomenology · Physics 2018-05-09 Yusuke Shimizu , Kenta Takagi , Morimitsu Tanimoto

The Daya Bay Collaboration has recently reported the precise measurement of $\theta_{13}\simeq 8.8^\circ \pm 0.8^\circ $ or $\theta_{13} \neq 0$ at 5.2 \sigma level. The observed non-zero $\theta_{13}$ can be accommodated by some general…

High Energy Physics - Phenomenology · Physics 2015-06-05 K. N. Deepthi , R. Mohanta

The top quark plays an important role in a number of new physics models, some of which introduce violations to some of the accidental symmetries of the SM, such as the lepton number conservation or introduce additional sources of others…

High Energy Physics - Experiment · Physics 2025-10-21 Sergio Sánchez Cruz

The observed leptonic mixing pattern could be explained by the presence of a discrete flavour symmetry broken into residual subgroups at low energies. In this scenario, a residual generalised CP symmetry allows the parameters of the PMNS…

High Energy Physics - Phenomenology · Physics 2015-11-25 Peter Ballett , Silvia Pascoli , Jessica Turner

We propose for the flavour structure of both the quark and lepton sectors, the principle of Universal Democracy (UD), which reflects the presence of a $Z_3$ symmetry. In the quark sector, we emphasize the importance of UD for obtaining…

High Energy Physics - Phenomenology · Physics 2013-04-05 G. C. Branco , N. Raimundo Ribeiro , J. I. Silva-Marcos

The standard model left-handed neutrinos and several right-handed neutrinos can obtain a tiny Dirac mass matrix through their mixings with relatively heavy Dirac fermions. In this Dirac seesaw scenario, the mixings involving the left-handed…

High Energy Physics - Phenomenology · Physics 2022-12-14 Su-Ping Chen , Pei-Hong Gu

The implications of the anarchy principle on CP violation in the lepton sector are investigated. A systematic method is introduced to compute the probability density functions for the CP-violating rephasing invariants of the PMNS matrix…

High Energy Physics - Phenomenology · Physics 2018-04-18 Jean-François Fortin , Nicolas Giasson , Luc Marleau

The observed hierarchy of the quark masses is interpreted as a signal for an underlying ``subnuclear democracy'' as the relevant symmetry of the quark mass terms. A simple breaking of the symmetry leads to a mixing between the second and…

High Energy Physics - Phenomenology · Physics 2009-10-30 Harald Fritzsch

We analyse the interplay of generalised CP transformations and the non-Abelian discrete group $T^{\prime}$ and use the semi-direct product $G_f= T^{\prime}\rtimes H_{\text{CP}}$, as family symmetry acting in the lepton sector. The family…

High Energy Physics - Phenomenology · Physics 2014-05-20 Ivan Girardi , Aurora Meroni , S. T. Petcov , Martin Spinrath

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 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 role of spontaneous lattice symmetry breaking in strongly interacting two dimensional Dirac systems. The fermion induced quantum (multi-)criticality is described by Dirac fermions coupled to a dynamical order parameter that…

Strongly Correlated Electrons · Physics 2020-04-22 Elliot Christou , Fernado de Juan , Frank Krüger

We investigate under which circumstances one can show the existence of leptonic CP violation with the help of a positive or negative signal in neutrinoless double beta decay. The possibilities of cancellations are investigated for special…

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

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

Neutrino oscillation experiments have confirmed that neutrinos are massive particles and lepton flavors are mixed. To explain the observed lepton mass spectra and flavor mixing patterns, flavor symmetry plays a crucial and unique role. In…

High Energy Physics - Phenomenology · Physics 2025-12-10 Chang-Qi Hu , Chun-Yuan Li , Xiao Liang , Xing-Hua Yang , Dai-Xing Zhang

Cobimaximal mixing predicts $\pi/4$ and $3\pi/2$ for the atmospheric angle and the Dirac CP-violating phase, respectively. These values are in tension with the neutrino globals fits. If this pattern was behind the lepton mixings, then it…

High Energy Physics - Phenomenology · Physics 2024-07-04 Juan Carlos Gómez-Izquierdo , Asahel Enrique Pozas Ramírez
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