Thermal production of ultrarelativistic right-handed neutrinos: Complete leading-order results
Feb, 201227 pages
Published in:
- JCAP 03 (2012) 029
e-Print:
- 1202.1288 [hep-ph]
Report number:
- BI-TP-2012-05
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Abstract: (arXiv)
The thermal production of relativistic right-handed Majorana neutrinos is of importance for models of thermal leptogenesis in the early Universe. Right-handed neutrinos can be produced both by 1 <-> 2 decay or inverse decay and by 2 -> 2 scattering processes. In a previous publication, we have studied the production via 1 <-> 2 (inverse) decay processes. There we have shown that multiple scattering mediated by soft gauge boson exchange also contributes to the production rate at leading order, and gives a strong enhancement. Here we complete the leading order calculation by adding 2 -> 2 scattering processes involving either electroweak gauge bosons or third-generation quarks. We find that processes with gauge interactions give the most important contributions. We also obtain a new sum rule for the Hard Thermal Loop resummed fermion propagator.Note:
- 27 pages, 7 figures. Error in the matrix element for the (subdominant) subprocess with s-channel fermion exchange corrected. This changes the corresponding phase space integral and the constant c_V. Numerically it increases the total 2 -> 2 rate by about 2 percent and the complete rate by about 1 percent. The main results and conclusions are unaffected
- neutrino: right-handed
- production: thermal
- leptogenesis: thermal
- neutrino: Majorana
- fermion: propagator
- hard thermal loop approximation
- sum rule
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