Kavli Affiliate: Peter W. Graham
| First 5 Authors: Peter W. Graham, Peter W. Graham, , ,
| Summary:
Recent observations of the cosmic microwave background (CMB) and baryon
acoustic oscillations (BAO) show some tension with a $Lambda$CDM cosmology.
For one, the cosmological parameters determined by the CMB are at odds with the
expansion history determined by latest BAO measurements. In addition, the
combined data has placed uncomfortably strong constraints on neutrino mass.
Both effects can be interpreted as negative neutrino mass, one describing the
change to the expansion history and the other one describing enhanced lensing.
In this paper, we show the current tensions can be solved with a single change
either to the lensing of the CMB or the expansion of the universe. We show
additional lensing could arise from a variety of models with new light fields.
However, these models rarely give the same signal in temperature and
polarization, giving a concrete test of the scenario. Alternatively, dark
sector models can explain the changes to the expansion by changing the
evolution of the matter density. These models introduce new forces, giving rise
to long range signals in the three-point statistics of galaxies. We discuss a
range of other examples which all illustrate the pattern that additional
signals should appear if these tensions are explained by beyond the Standard
Model physics.
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