scholarly journals Aspects of high scale leptogenesis with low-energy leptonic CP violation

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
A. Granelli ◽  
K. Moffat ◽  
S. T. Petcov
Keyword(s):  
Cp Violation ◽  
Low Energy ◽  
Type I ◽  
Neutrino Mixing ◽  
High Scale ◽  
Boltzmann Equations ◽  
Majorana Neutrinos ◽  
Pmns Matrix ◽  
Neutrino Experiments ◽  
Majorana Phases

Abstract 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 investigate the 1-to-2 and the 2-to-3 flavour regime transitions, where the 1, 2 and 3 leptogenesis flavour regimes in the generation of the baryon asymmetry of the Universe ηB are described by the Boltzmann equations. Concentrating on the 1-to-2 flavour transition we determine the general conditions under which ηB goes through zero and changes sign in the transition. Analysing in detail the behaviour of ηB in the transition in the case of two heavy Majorana neutrinos N1,2 with hierarchical masses, M1 ≪ M2, we find, in particular, that i) the Boltzmann equations in many cases fail to describe correctly the generation of ηB in the 1, 2 and 3 flavour regimes, ii) the 2-flavour regime can persist above (below) ∼ 1012 GeV (∼ 109 GeV), iii) the flavour effects in leptogenesis persist beyond the typically considered maximal for these effects leptogenesis scale of 1012 GeV. We further determine the minimal scale M1min at which we can have successful leptogenesis when the CPV is provided only by the Dirac or Majorana phases of the PMNS matrix as well as the ranges of scales and values of the phases for having successful leptogenesis. We show, in particular, that when the CPV is due to the Dirac phase δ, there is a direct relation between the sign of sin δ and the sign of ηB in the regions of viable leptogenesis in the case of normal hierarchical light neutrino mass spectrum; for the inverted hierarchical spectrum the same result holds for M1 ≲ 1013 GeV. The considered different scenarios of leptogenesis are testable and falsifiable in low-energy neutrino experiments.

scholarly journals Radiative decays of charged leptons as constraints of unitarity polygons for active-sterile neutrino mixing and CP violation

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Zhi-zhong Xing ◽  
Di Zhang
Keyword(s):  
Cp Violation ◽  
Complex Plane ◽  
Sterile Neutrino ◽  
Radiative Decays ◽  
Neutrino Mixing ◽  
Seesaw Mechanism ◽  
Majorana Neutrinos ◽  
Alpha Beta ◽  
Charged Leptons ◽  
Pmns Matrix

AbstractWe calculate the rates of radiative $$\beta ^- \rightarrow \alpha ^- + \gamma $$ β - → α - + γ decays for $$(\alpha , \beta ) = (e, \mu )$$ ( α , β ) = ( e , μ ) , $$(e, \tau )$$ ( e , τ ) and $$(\mu , \tau )$$ ( μ , τ ) by taking the unitary gauge in the $$(3+n)$$ ( 3 + n ) active-sterile neutrino mixing scheme, and make it clear that constraints on the unitarity of the $$3\times 3$$ 3 × 3 Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrix U extracted from $$\beta ^- \rightarrow \alpha ^- + \gamma $$ β - → α - + γ decays in the minimal unitarity violation scheme differ from those obtained in the canonical seesaw mechanism with n heavy Majorana neutrinos by a factor 5/3. In such a natural seesaw case we show that the rates of $$\beta ^- \rightarrow \alpha ^- + \gamma $$ β - → α - + γ can be used to cleanly and strongly constrain the effective apex of a unitarity polygon, and compare its geometry with the geometry of its three sub-triangles formed by two vectors $$U^{}_{\alpha i} U^*_{\beta i}$$ U α i U β i ∗ and $$U^{}_{\alpha j} U^*_{\beta j}$$ U α j U β j ∗ (for $$i \ne j$$ i ≠ j ) in the complex plane. We find that the areas of such sub-triangles can be described in terms of the Jarlskog-like invariants of CP violation $${{\mathcal {J}}}^{ij}_{\alpha \beta }$$ J α β ij , and their small differences signify slight unitarity violation of the PMNS matrix U.

scholarly journals The Nature of Massive Neutrinos

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
S. T. Petcov
Keyword(s):  
Neutrino Mass ◽  
Current Data ◽  
Future Research ◽  
Type I ◽  
Neutrino Mixing ◽  
Mass Generation ◽  
Triplet Model ◽  
Majorana Neutrinos ◽  
Massive Neutrinos ◽  
Neutrino Mass Generation

The compelling experimental evidences for oscillations of solar, reactor, atmospheric, and accelerator neutrinos imply the existence of 3-neutrino mixing in the weak charged lepton current. The current data on the 3-neutrino mixing parameters are summarised and the phenomenology of 3-νmixing is reviewed. The properties of massive Majorana neutrinos and of their various possible couplings are discussed in detail. Two models of neutrino mass generation with massive Majorana neutrinos—the type I see-saw and the Higgs triplet model—are briefly reviewed. The problem of determining the nature, Dirac or Majorana, of massive neutrinos is considered. The predictions for the effective Majorana mass|〈m〉|in neutrinoless double-beta-((ββ)0ν-) decay in the case of 3-neutrino mixing and massive Majorana neutrinos are summarised. The physics potential of the experiments, searching for(ββ)0ν-decay for providing information on the type of the neutrino mass spectrum, on the absolute scale of neutrino masses, and on the Majorana CP-violation phases in the PMNS neutrino mixing matrix, is also briefly discussed. The opened questions and the main goals of future research in the field of neutrino physics are outlined.

scholarly journals Model independent analysis of Dirac CP violating phase for some well-known mixing scenarios

2021 ◽  
pp. 2150188
Author(s):  
Sumit K. Garg
Keyword(s):  
Cp Violation ◽  
Numerical Investigation ◽  
Parameter Space ◽  
Neutrino Mixing ◽  
Mixing Angles ◽  
Complex Rotation ◽  
Rotation Matrices ◽  
Independent Analysis ◽  
Model Independent ◽  
Pmns Matrix

In this paper, we present a model independent analysis of Leptonic CP violation for some well-known mixing scenarios. In particular, we considered modified schemes for bimaximal (BM), democratic (DC), hexagonal (HG) and tribimaximal (TBM) mixing for our numerical investigation. These model independent corrections to mixing matrices are parametrized in terms of complex rotation matrices [Formula: see text] with related modified PMNS matrix of the forms [Formula: see text] where [Formula: see text] is a complex rotation in [Formula: see text] sector and [Formula: see text] is unperturbed mixing scheme. We present generic formulae for mixing angles, Dirac CP phase [Formula: see text] and Jarlskog invariant [Formula: see text] in terms of correction parameters. The parameter space of each modified mixing case is scanned for fitting neutrino mixing angles using [Formula: see text] approach and the corresponding predictions for Leptonic CP phase [Formula: see text] and Jarlskog invariant [Formula: see text] has been evaluated from allowed parameter space. The obtained ranges are reported for all viable cases.

scholarly journals NEUTRINO MASSES, COSMOLOGICAL BOUND AND FOUR ZERO YUKAWA TEXTURES

2011 ◽  
Vol 26 (32) ◽  
pp. 2427-2435 ◽  
Author(s):  
BISWAJIT ADHIKARY ◽  
AMBAR GHOSAL ◽  
PROBIR ROY
Keyword(s):  
Cp Violation ◽  
Light Neutrino ◽  
Neutrino Masses ◽  
Type I ◽  
High Scale ◽  
Parameter Region ◽  
Weak Basis ◽  
Majorana Mass ◽  
Mass Matrices ◽  
Normal Mass

Four zero neutrino Yukawa textures in a specified weak basis, combined with μτ symmetry and type-I seesaw, yield a highly constrained and predictive scheme. Two alternately viable 3×3 light neutrino Majorana mass matrices mνA/mνB result with inverted/normal mass ordering. Neutrino masses, Majorana in character and predicted within definite ranges with laboratory and cosmological inputs, will have their sum probed cosmologically. The rate for 0νββ decay, though generally below the reach of planned experiments, could approach it in some parameter region. Departure from μτ symmetry due to RG evolution from a high scale and consequent CP violation, with a Jarlskog invariant whose magnitude could almost reach 6×10-3, are explored.

scholarly journals THE MINIMAL TYPE-I SEESAW MODEL AND FLAVOR-DEPENDENT LEPTOGENESIS

2008 ◽  
Vol 23 (21) ◽  
pp. 3403-3407 ◽  
Author(s):  
ZHI-ZHONG XING ◽  
SHUN ZHOU
Keyword(s):  
Yukawa Coupling ◽  
Baryon Number ◽  
Type I ◽  
Neutrino Mixing ◽  
Coupling Matrix ◽  
Seesaw Model ◽  
Majorana Neutrinos ◽  
Minimal Type ◽  
Baryon Number Asymmetry

In this talk, we first give a brief review of the so-called minimal seesaw models and then concentrate on the minimal type-I seesaw model with two almost degenerate right-handed Majorana neutrinos of [Formula: see text]. A specific texture of the neutrino Yukawa coupling matrix is proposed to achieve the nearly tri-bimaximal neutrino mixing pattern. This ansatz predicts (1) θ23 = π/4, |δ| = π/2 and sin 2θ12 = (1 − 2tan2θ13)/3 in the m1 = 0 case; and (2) θ23 = π/4 and θ13 = 8 = 0 in the m3 = 0 case. In both cases, the cosmological baryon number asymmetry can be explained via the resonant leptogenesis mechanism. Finally, we demonstrate the significance of flavor-dependent effects in our leptogenesis scenario.

scholarly journals Correlations between low energy leptonic CP violation and leptogenesis in the light of recent experiments

2014 ◽  
Vol 29 (20) ◽  
pp. 1450104
Author(s):  
H. Zeen Devi
Keyword(s):  
Cp Violation ◽  
High Energy ◽  
Energy Scale ◽  
Low Energy ◽  
Type I ◽  
Planck Data ◽  
Cp Violations ◽  
Neutrino Sector ◽  
High Energy Scale ◽  
The Universe

Leptogenesis is the most favorable mechanism for generating the observed baryon asymmetry of the universe (BAU) which implies CP violation in the high energy scale. The low energy leptonic CP violation is expected to be observed in the neutrino oscillations and 0ν2β decay experiments. Generally, it is not possible to connect both the CP violations. Here we revisit the issue of connecting the two in flavored leptogenesis scenario within the Type I seesaw in the light of recent neutrino oscillation and Planck data. With the recent precise measurements of θ13 and BAU, we are able to find new correlations between the low and high energy CP violating phases when leptogenesis occurs at temperature between 109 to 1012 GeV and there is no contribution to CP violation from the heavy neutrino sector.

Neutrinos and cosmological matter–antimatter asymmetry: A minimal seesaw with Frampton–Glashow–Yanagida ansatz

2017 ◽  
Vol 32 (16) ◽  
pp. 1742004
Author(s):  
Jue Zhang ◽  
Shun Zhou
Keyword(s):  
Renormalization Group ◽  
Low Energy ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
High Energies ◽  
Seesaw Model ◽  
Mixing Parameters ◽  
Energy Neutrino ◽  
Flavor Mixing ◽  
Neutrino Experiments

In light of the latest neutrino data, we revisit a minimal seesaw model with the Frampton–Glashow–Yanagida ansatz. Renormalization-group running effects on neutrino masses and flavor mixing parameters are discussed and found to essentially have no impact on testing such a minimal scenario in low-energy neutrino experiments. However, since renormalization-group running can modify neutrino mixing parameters at high energies, it does affect the leptogenesis mechanism, which is responsible for the observed matter–antimatter asymmetry in our Universe. Furthermore, to ease the conflict between the naturalness argument and the successful leptogenesis, a special regime for resonant leptogenesis is also emphasized.

scholarly journals On the determination of the $\theta_{23}$ octant in long baseline neutrino experiments

2018 ◽  
Author(s):  
C.R. Das ◽  
Jukka Maalampi ◽  
João Pulido ◽  
Sampsa Vihonen
Keyword(s):  
Cp Violation ◽  
Baseline Length ◽  
Neutrino Mixing ◽  
Mixing Angle ◽  
Time Ratio ◽  
Long Baseline ◽  
Run Time ◽  
Neutrino Experiments

We study the possibility of determining the octant of the neutrino mixing angle 23, that is, whether 23 > 45 or 23 < 45, in long baseline neutrino experiments. Here we numerically derived the sensitivity limits within which these experiments can determine, by measuring the probability of the ! e transitions, the octant of 23 with a 5 certainty. The interference of the CP violation angle with these limits, as well as the effects of the baseline length and the run-time ratio of neutrino and antineutrino modes of the beam have been analyzed.

ON THE ROLE OF LOW-ENERGY CP VIOLATION IN LEPTOGENESIS

2009 ◽  
Vol 24 (18) ◽  
pp. 1399-1409 ◽  
Author(s):  
STEVE BLANCHET ◽  
PAVEL FILEVIEZ PÉREZ
Keyword(s):  
Cp Violation ◽  
Low Energy ◽  
Type I ◽  
Unified Theory ◽  
Grand Unified Theory ◽  
Inverted Hierarchy ◽  
Lepton Asymmetry ◽  
Type Iii ◽  
New States

The link between low-energy CP violation and leptogenesis became more accessible with the understanding of flavor effects. However, a definite well-motivated model where such a link occurs was still lacking. Adjoint SU(5) is a simple grand unified theory where neutrino masses are generated through the Type I and Type III seesaw mechanisms, and the lepton asymmetry is generated by the fermionic triplet responsible for the Type III seesaw. We focus exclusively on the case of inverted hierarchy for neutrinos, and we show that successful flavored leptogenesis in this theory strongly points towards low-energy CP violation. Moreover, since the range of allowed masses for the triplet is very restricted, we find that the discovery at the LHC of new states present in the theory, together with proton decay and unification of gauge couplings, can conspire to provide a hint in favor of leptogenesis.

scholarly journals Connecting leptonic CP violation, lightest neutrino mass and baryon asymmetry through type II seesaw

2015 ◽  
Vol 30 (09) ◽  
pp. 1550045 ◽  
Author(s):  
Rupam Kalita ◽  
Debasish Borah
Keyword(s):  
Cp Violation ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Baryon Asymmetry ◽  
Type I ◽  
Type Ii ◽  
Neutrino Mixing ◽  
Mixing Angles ◽  
The Universe ◽  
Mass Type

We study the possibility of connecting leptonic Dirac CP phase δ, lightest neutrino mass and baryon asymmetry of the universe within the framework of a model where both type I and type II seesaw mechanisms contribute to neutrino mass. Type I seesaw gives rise to Tri-Bimaximal (TBM) type neutrino mixing whereas type II seesaw acts as a correction in order to generate nonzero θ13. We derive the most general form of type II seesaw mass matrix which cannot only give rise to correct neutrino mixing angles but also can generate nontrivial value of δ. Considering both the cases where type II seesaw is subleading and is equally dominant compared to type I seesaw, we correlate the type II seesaw term with δ and lightest neutrino mass. We further constrain the Dirac CP phase δ and hence the type II seesaw mass matrix from the requirement of producing the observed baryon asymmetry through the mechanism of leptogenesis.

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