Leptogenesis from a U(1) D resonance
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Springer
Received: May 9, Revised: July 9, Accepted: July 23, Published: August 20,
2020 2020 2020 2020
Eung Jin Chun,a Arnab Dasguptab and Sin Kyu Kangb a
School of School of Physics, Korea Institute for Advanced Study, Seoul 02455, Korea b School of Liberal Arts, Seoul-Tech, Seoul 139-743, Korea
E-mail: [email protected], [email protected], [email protected] Abstract: We propose a novel mechanism to realize leptogenesis through the BreitWigner resonance of a dark U(1)D gauge boson ZD , which mediates lepton number violating annihilations of dark matter (DM) in the context of the scotogenic model with a U(1)D . The processes occur out of equilibrium and DM freezes out later giving rise to the observed abundance. The CP violation required for leptogenesis can be achieved by the interference between tree-level t-channel scattering of DM and the subsequent 1-loop mediated by ZD , which arises due to the unremovable imaginary part of either the ZD propagator coming from its self-energy correction or the 1-loop giving rise to the effective coupling of ZD ν¯ν. Keywords: Beyond Standard Model, Cosmology of Theories beyond the SM, Neutrino Physics ArXiv ePrint: 2004.14189
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP08(2020)095
JHEP08(2020)095
Leptogenesis from a U(1)D resonance
Contents 1
2 Model
3
3 Leptogenesis through resonance of U(1)D gauge boson
5
4 Results and discussion
8
5 Conclusion
10
A Details of the effective ZD coupling
10
B Details of the loop function F±
12
1
Introduction
One of the great mysteries of our universe is the origin of the baryon asymmetry due to which net resultant baryons comprising almost 4% of the entire energy budget of the Universe are generated. Long time ago, Sakharov found three ingredients to achieve the excess of baryon over anti-baryon through some processes, which are 1) B/L violation 2) C and CP violation and 3) a departure from thermal equilibrium. In addition to these conditions, the processes resulting in CP asymmetry should abide by NanopoulousWeinberg theorem [1] and furthermore Adhikari-Rangarajan theorem [2]. There have been early attempts to generate the baryon asymmetry from 1 → 2 decay proposed in [3, 4] and also it can be dynamically generated via leptogenesis where lepton number, C and CP violating 2-body out-of-equilibrium decays of heavy Majorana neutrinos produce a primodial lepton asymmetry, which is partially converted into the baryon asymmetry via B + L violating sphaleron processes [5]. However, leptogenesis through type I seesaw is successful for the mass scale of the heavy Majorana neutrino larger than 109 GeV [6], which is undesirable due to the hopeless possibility to probe it at collider experiments and a tension with naturalness of Higgs potential [7, 8]. Motivated by those problems in vanilla leptogenesis, in this work, we propose a new promising possibility for leptogenesis realized naturally at low scale. The major difficulty to achieve leptogenesis at low scale such as 1-10
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