Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Leptogenesis With Many Neutrinos   We consider leptogenesis in scenarios with many neutrino singlets. We find
that the lower bound for the reheating temperature can be significantly relaxed
with respect to the hierarchical three neutrino case. We further argue that the
upper bound for the neutrino mass scale from leptogenesis gets significantly
lifted in these scenarios. As a specific realization, we then discuss an
extra-dimensional model, where the large number of neutrinos is provided by
Kaluza-Klein excitations.

18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an