The temperature fluctuations in the cosmic microwave background (CMB) are in principle dependent on all the scalar fields that are light at the time of inflation. Models of new interactions predict many possible light scalars at the time of inflation. I am interested in the multiple (significant but not yet compelling) anomalies in the CMB power spectrum as potential indicators of the physics at the time of inflation. Among these are an indication for more power in (roughly) the southern galactic hemisphere. This could emerge if there were other active ingredients beyond a single slowly-rolling inflaton, in which case the extra physics could have a different spatial dependence from the dominant inflaton.
There does seem to be evidence of an asymmetry in the CMB power spectrum. It is not yet compelling but is certainly suggestive. It seems to be at relatively large scales. My son Evan and I showed used available data to show that it is not present at the first acoustic peak.
With my students, K. Dutta and A. Ross, we explored whether this could be signal a fast-roll phase, with partial success. With Lorenzo Sorbo we are now looking at whether this could be due to an axion active at the time of inflation.
I also have interests in the physics of the very early universe.