Baryogenesis and lepton number violation

Plümacher, M.

doi:10.1007/s002880050418

Cited by 288 publications

(319 citation statements)

References 19 publications

(51 reference statements)

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“…This possibility has been considered in many works [14,15,16]. In [8] an analytical condition for the validity of a calculation of the efficiency factor κ f 1 in the HL was found.…”

Section: Introductionmentioning

confidence: 99%

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Leptogenesis beyond the limit of hierarchical heavy neutrino masses

Blanchet¹,

Bari²

2006

J. Cosmol. Astropart. Phys.

121

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We calculate the baryon asymmetry of the Universe in thermal leptogenesis beyond the usual lightest right-handed (RH) neutrino dominated scenario (N 1 DS) and in particular beyond the hierarchical limit (HL), M 1 ≪ M 2 ≪ M 3 , for the RH neutrino mass spectrum. After providing some orientation among the large variety of models, we first revisit the central role of the N 1 DS, with new insights on the dynamics of the asymmetry generation and then discuss the main routes departing from it, focusing on models beyond the HL. We study in detail two examples of 'strong-strong' washout scenarios: one with 'maximal phase' and the limit of very large M 3 , studying the effects arising when δ 2 ≡ (M 2 − M 1 )/M 1 is small. We extend analytical methods already applied to the N 1 DS showing, for example, that, in the degenerate limit (DL), the efficiency factors of the RH neutrinos become equal with the single decay parameter replaced by the sum. Both cases disprove the misconception that close RH neutrino masses necessarily lead to a final asymmetry enhancement and to a relaxation of the lower bounds on M 1 and on the initial temperature of the radiationdominated expansion. We also explain why leptogenesis tends to favor normal hierarchy compared to inverted hierarchy for the left-handed neutrino masses.

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“…This possibility has been considered in many works [14,15,16]. In [8] an analytical condition for the validity of a calculation of the efficiency factor κ f 1 in the HL was found.…”

Section: Introductionmentioning

confidence: 99%

“…The general expression for the final asymmetry Eq. (7) reduces to η B ≃ 10 −2 ε 1 κ f 1 , where κ f 1 can be calculated solving a system of just two kinetic equations [14,7,9], obtained from the general set (cf. (8) and (9)) neglecting the asymmetry generation and the wash-out terms from the two heavier RH neutrinos.…”

Section: Revisiting the N 1 Dsmentioning

confidence: 99%

Leptogenesis beyond the limit of hierarchical heavy neutrino masses

Blanchet¹,

Bari²

2006

J. Cosmol. Astropart. Phys.

121

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“…They correspond to two different realizations of the sign flip: the Example I(l) implements the inequality (m ν ) 22 > (m ν ) 33 and in the Example II(l) the element (m ν ) 23 changes the sign. For simplicity we take ǫ 13 = ǫ 11 = 0.…”

Section: Phenomenological Consequencesmentioning

confidence: 99%

“…The equality (33) means that the determinant of the Majorana matrix of the RH neutrino components is of the order λ 2 · O(ǫ 2 ij ) or smaller, and consequently, the RH neutrino masses have strong hierarchy:…”

Section: Quark Mixingmentioning

confidence: 99%

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Neutrino masses and mixing: singular mass matrices and quark–lepton symmetry

Doršner

Smirnov

2004

Nuclear Physics B

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We suggest an approach to explain the observed pattern of the neutrino masses and mixing which employs the weakly violated quark-lepton equality and does not require introduction of an ad hoc symmetry of the neutrino sector. The mass matrices are nearly equal for all quarks and leptons. They have very small determinant and hierarchical form with expansion parameter λ ∼ sin θ c ∼ m µ /m τ . The latter can be realized, e.g., in the model with U (1) family symmetry.The equality is violated at the ∼ λ 2 level. Large lepton mixing appears as a result of summation of the neutrino and charged lepton rotations which diagonalize corresponding mass matrices in contrast with the quark sector where the up quark and down quark rotations cancel each other.We show that the flip of the sign of rotation in the neutrino sector is a result of the seesaw mechanism which also enhances the neutrino mixing. In this approach one expects, in general, deviation of the 2-3 mixing from maximal, s 13 ∼ (1 -3)λ 2 , hierarchical neutrino mass spectrum, and m ee < 10 −2 eV. The scenario is consistent with the thermal leptogenesis and (in SUSY context) bounds on lepton number violating processes, like µ → eγ.

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Matter-antimatter asymmetry of the universe

Buchmüller¹

2001

Ann. Phys.

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The asymmetry of the universe between matter and antimatter in the universe is related to neutrino properties due to non-perturbative processes in the high-temperature symmetric phase of the standard model. We show that the neutrino masses inferred from the solar and atmospheric neutrino anomalies are consistent with the hypothesis that the observed cosmological matter density has been created in decays of heavy Majorana neutrinos in the early universe.

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Baryogenesis and lepton number violation

Cited by 288 publications

References 19 publications

Leptogenesis beyond the limit of hierarchical heavy neutrino masses

Leptogenesis beyond the limit of hierarchical heavy neutrino masses

Neutrino masses and mixing: singular mass matrices and quark–lepton symmetry

Matter-antimatter asymmetry of the universe

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