Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cosmology with Independently Varying Neutrino Temperature and Number   We consider Big Bang nucleosynthesis and the cosmic microwave background when
both the neutrino temperature and neutrino number are allowed to vary from
their standard values. The neutrino temperature is assumed to differ from its
standard model value by a fixed factor from Big Bang nucleosynthesis up to the
present. In this scenario, the effective number of relativistic degrees of
freedom, $N_{\rm eff}^{\rm CMB}$, derived from observations of the cosmic
microwave background is not equal to the true number of neutrinos, $N_\nu$. We
determine the element abundances predicted by Big Bang nucleosynthesis as a
function of the neutrino number and temperature, converting the latter to the
equivalent value of $N_{\rm eff}^{\rm CMB}$. We find that a value of $N_{\rm
eff}^{\rm CMB} \approx 3$ can be made consistent with $N_\nu = 4$ with a
decrease in the neutrino temperature of $\sim 5\%$, while $N_\nu = 5$ is
excluded for any value of $N_{\rm eff}^{\rm CMB}$. No observationally-allowed
values for $N_{\rm eff}^{\rm CMB}$ and $N_\nu$ can solve the lithium problem.

26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph