Leptogenesis
Giorgio Arcadi
University of Rome ThreeGiven the broadness of the subject,

this will be an overview of some selected topics.

Apologizes if some interesting topics (and references) will not becovered.

Giorgio Arcadi

Lomonosov Conference 25-08-2021

Baryogenesis in a nutshell
𝜂=𝑛𝐵 − 𝑛𝐵ത
= 6.02 − 6.18 × 10−10𝑛𝛾

Planck Collaboration, arXiv:1807.06209

Dynamical mechanism for the generation of the matter-antimatter asymmetry (BAU) in theprimordial Universe
Violation of Baryon Number (B);
Necessary requirements
A.D. Sakharov Pisma Zh.Eksp.Teor.Fiz. 5 (1967) 32-35, JETP
Lett. 5 (1967) 24-27, Sov.Phys.Usp. 34 (1991) 5, 392-393

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Violation of C and CP;
Departure from Thermal Equilibrium
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The Standard Model cannot succesfully account for the BAU. We need to look for Physics beyond the StandardModel.

Direct Baryogenesis: mechanism which created dynamicallya baryon-antibaryon asymmetry.
Baryogenesis

Leptogenesis: First dynamical generation of a lepton
asymmetry. Conversion of the lepton asymmetry into a baryon
asymmetry, e.g. by B-L Sphalerons.
Source𝑑𝑌𝑁=⋯
𝑑𝑇

State(s) generating the asymmetry e.g.
out-of-equilibrium decaying heavyneutrino𝜂 ↔ 𝑌Δ𝐵 = 𝐴 𝑌Δ(𝐵−𝐿)
System of Boltzmann’sequations
Giorgio Arcadi𝑑𝑌Δ(𝐵−𝐿)=⋯𝑑𝑇

Details of the system depend on thespecific model
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Mechanism for generation of neutrino mass.
ν(Original idea from M. Fukugida and T. Yanagida Phys. Lett.
B174 (1986) 45-47)

NConnection with other observables
Leptogenesis requires violation ofthe lepton number (LNV)
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LeptogenesisExperimental tests
e.g:
Neutrinoless Double-beta decay
Searches of extra neutrinos
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Searches in Low energy
experiments

LHC
100 GeV 1 TeV

GeVPossible connection with low energy phases.
Lepton number violating processes
106 GeV1012 GeV
𝑀𝑁

Leptogenesis from
Oscillations (ARS)Resonant Leptogenesis

Asaka, Eijima, Ishida, 1112.5565
Asaka, Shaposhinokov, 0505013
Akhmedov, Rubakov, Smirnov 9803255

A. Pilaftis and T. E. J. Underwood Nucl. Phys. B692, 303 (2004)
A. Abada, H. Aissaoui, M. Losada 0406304

Leptogenesis from LPV
decay of the Higgs

Thermal Leptogenesis
M. Fukugida and T. Yanagida Phys. Lett. B174 (1986) 45-47
W. Buchmuller, P. Di Bari, M. Plumacher arXiv:0401240
R. Barbiere, P. Creminelli, A. Strumia, N. Tetradis

T. Hambye and D. Teresi arXiv:1606.00017
Eijima, Shaposhnikov 1703.06085
Eijima, Shaposhnikov, Timiryasov 1808.10833

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Case of study: interaction responsible ofasymmetry generation associated toright-handed (sterile) neutrinos involvedin the mass generation of active
neutrinos.

𝑀𝑁 > 100 𝐺𝑒𝑉
Out-of-equilibrium (L-violating) decays of right-handed
neutrinos produced in the Early Universe. CP-asymmetry
generated by interference between tree level and loop
diagrams.

𝑀𝑁 < 100 𝐺𝑒𝑉
Examples of other possibilities (not exhaustive list):
L-violating decays of the Higgs
L. Covi, E. Roulet, F. Vissani 9605319
S. Antush, S. F. King 0405093
L. Boubekeur, T. Hambye, G. Senjanovic 0404038
T. Hallgren, T. Konstandin, T. Ohlson 0710.2408
T. Hambye 1212.2888
T. Rink, W. Rodejohann, K. Schmitz 2006.03021
J. Harz et al; 2106.10838
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Asymmetry generatedby CP-violating
oscillations of extra
heavy neutrinos.

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ARS Leptogenesis
A.Abada, G.A., V. Domcke, M. Lucente 1709.00415
G. Ghiglieri, M. Laine 1703.06087, 1811.09171
Hernandez, Kekic, Lopez-Pavon, Racker, Salvado 1606.06719
A. Abada, G.A., V. Domcke, M. Lucente 1507.06215
Canetti, Drewes, Fossard, Shaposhnikov 1208.4607
Asaka, Eijima, Ishida, 1112.5565
Asaka, Shaposhinokov, 0505013
Akhmedov, Rubakov, Smirnov 9803255

Right-handed neutrinos
thermally produced in Early
Universe with CP-violatingoscillations.

(Ahkmedov Rubakov Smirnov)

Converted into baryon
asymmetry by Sphalerons

Asymmetry converted
into asymmetry between
active flavors

Asymmetry in the active sector acts as background potentialand enhances the asymmetry in the RH sector
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Limits on Light Extra Neutrinos
ARS Leptogenesis requires extra neutrinos to be at mostas heavy as few tens of GeV.
Possibility of tests from low energy experiments.
A. Atre, T. Han, S. Pascoli, B. Zhang 0901.3589
E.J. Chun et al, arXiv:1711:02865
A. Abada, C. Hati, X. Marcano, A. M. Texeira, arXiv:1904.05367

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The minimal realization of the ARS mechanism requires a pair of almost mass degenerate heavy (as opposed to active neutrinos)
neutrinos.
E.J. Chun et al, arXiv:1711.02865
M. Drewes, B. Garbrecht, D. Gueter, J. Klaric 1609.09609Type-I See-saw
P. Hernandez, M. Kekic, J. Lopez-Pavon, J. Racker, J. Salvado 1606.06719

L. Canetti, M. Drewes, T. Frossard, M. Shaposhnikov 1208.4607

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Linear+Inverse See-Saw
A. Abada, G.A., V. Domcke, M. Lucente 1507.06215

In linear+inverse See-saw heavy neutrinos are pseudo-dirac

Inverse See-Saw
A. Abada, G.A., V. Domcke, M. Lucente 1709.00415

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Including LNV decays of the Higgs
LNV DecaysLeptogenesis from:

Oscillations+T. Hambye and D. Teresi arXiv:1606.00017(See also
Eijima, Shaposhnikov 1703.06085
Eijima, Shaposhnikov, Timiryasov
1808.10833)

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ARS Leptogenesis from 3 heavy neutrinos
Degeneracy removed for leptogenesis from 3 (or more) neutrinos.
(Drewes and Garbrecht, arXiv:1206.5537
P. Hernandez, M. Kekic, J. Lopez-Pavon, J. Racker, N. Ruis 1508.03676)

𝑀1 [𝐺𝑒𝑉]
A. Abada, G.A., V. Domcke, M. Drewes, J. Klaric, M. LucentearXiv: 1810.12463
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Unifying leptogenesis from oscillations and resonant leptogenesis

J. Klaric, M. Shaposhnikov, I. Timiryasov,arXiv:2103.16545(Extension to three neutrino case,M. Drewes, Y. Georis, J. Klaric, 2106.16226)

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TeV scale Leptogenesis in L-R modelSee-saw based on 𝑆𝑈 2 𝐿 × 𝑆𝑈 2 𝑅 × 𝑈 1 𝐵−𝐿
P.S. B. Dev, C. Lee, R. Mohapatra 1503.04970(See also A. Abada, P. Hosteins, F. Josse-Michaux, S. Lavignac0808.2058)

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𝑝𝑝 → 𝑊𝑅± → 𝑁𝑙 ±Inverse See-saw+Linear See-saw

𝑅𝑙𝑙 =𝑆𝑎𝑚𝑒 𝑆𝑖𝑔𝑛
𝐷𝑖𝑙𝑒𝑝𝑡𝑜𝑛𝑠
𝑂𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑆𝑖𝑔𝑛

Type-I See-saw.
A. Das, P. S. B. Dev, R. Mohapatra, arXiv:1709.06553

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Test mass degeneracy through charge asymmetries in 𝑊𝑅 decays.

P.S.B. Dev, R. Mohapatra, Y. Zhang, 1904.04787

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Leptogenesis and neutrino option
I.Brivio, K. Moffat, S. Pascoli, S.T. Petcov, J. Turner JHEP 10 (2019) 059
V. Brdar, J. Hembolt, S. Iwamoto, K. Schmitz, Phys. Rev. D100 (2019) 075029

Interesting possibilitity: Right-handed neutrino can provide
successfule leptogenesis and at the same time explain thegeneration of the EW scale and leptogenesis.

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Leptogenesis from phases of PMNS only
Finally an example of high energy See-saw.

𝑀1 = 1010 𝐺𝑒𝑉

K. Moffat, S. Pascoli, S. Petcov,
J. Turner JHEP 03 (2019) 034

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Conclusions
Leptogenesis is a viable option to explain the generation of the baryon asymmetryof the Universe.
It can be related to the origin of neutrino masses and many low energy
observables.
Successful leptogenesis can occur for a broad range of New Physics Scales. Verychallenging scenario to probe as a whole.
There are nevertheless interesting individual scenarios which can be tested atpresent and next future experimental facilities.
Giorgio Arcadi

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Back upLeptogenesis from MeV scale see-sawV. Domcke, M. Drewes, M. Hufnagel, M. Lucente ,JHEP 01 (2021) 200, arXiv:2009.11678
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M. Drewes, Y. Georis, J. Klaric, 2106.16226

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Number of expected events at
future colliders

S. Antush, E. Cazzato, M. Drewes, O. Fisher, B. Gabrecht
JHEP 09 (2018) 124,1710.03744

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