02:35:51	asimina arvanitaki:	there should be similar modes for the axion at these large field values
02:36:30	asimina arvanitaki:	the axion I mean
02:36:38	asimina arvanitaki:	saxion
02:40:35	Raymond Co:	Thanks Mina for the question and the reference. I am studying it now.
02:45:58	Guido Mueller:	›No rush
02:46:15	Raymond Co:	Mina, do you mind pointing me to where it states that tachyonic instability is always there? What I see below Eq. 50 is that “Using the fact that field excursions are sub-Planckian, Eq. 21, we find that as long as the UV cutoff is above the weak scale, then suppressed production of photons is negligible.”
02:52:43	Raymond Co:	Due to this reason, we have considered axion couplings to everything except the photon. We find that the thermal interactions only wash out a small fraction of the PQ charge as long as the saxion field value is much larger than the temperature.
02:57:43	keisukeharigaya@ias.edu:	Mina, thank you for the reference. That paper does not take into account the possible existence of a conserved quantity. (Perhaps that is OK for their setup since it is the violation of the axion shift symmetry which induces the motion.) With the axion-photon coupling, a linear combination of the axion shift symmetry and the photon helicity density is conserved. Even if the axion charge is transferred into helicity density, the helicity density can go back to the axion charge. The system reaches equilibrium, where one can show that the most of the charge is stored in the axion. Also, when helical gauge fields are produced, chiral anomaly produces fermion chiral asymmetry, which cancels the tachyonic instability. Some of these issues are discussed in https://arxiv.org/abs/1806.08769 in the context of oscillating axions rather than rotations.
03:00:36	asimina arvanitaki:	thank you for this
03:01:01	asimina arvanitaki:	I still have to think about ti, but what about the saxion?
03:03:29	David Tanner:	Was there also a supermassive black hole in the splash? 
03:04:47	asimina arvanitaki:	@keisuke does it change anything in your parameter space?
03:07:55	asimina arvanitaki:	I am still confused because the photon field thermalizes
03:08:06	asimina arvanitaki:	so how can it go back to coherent field motion?
03:08:54	Raymond Co:	Since most of the charge is still in the form of the rotation from the argument Keisuke gave, the depletion of the charge is much less than O(1) and it does not affect our parameter space.
03:09:10	Raymond Co:	It may be helpful to have look at Sec. I. of the Supplemental Materials in axiogenesis https://arxiv.org/pdf/1910.02080.pdf. The depletion is suppressed by T^2/S^2 where S = the saxion field value even if equilibrium is reached.
03:10:29	Raymond Co:	However, again, we do not include the photon couplings but the idea should be analogous to those fermion interactions.
03:11:10	asimina arvanitaki:	I am afraid I am still confused by your statement
03:11:15	asimina arvanitaki:	bosons are different
03:16:10	William Wester:	Beyond streams, there are models involving cusps … very large over densities with very narrow velocity dispersion (Sikivie et al models) when DM flows into and turn arounds in our local neighborhood. Can you comment on your view of what’s known about where our solar system might live?
03:21:28	Raymond Co:	You are right that the bosons are different (tachyonic instability can be efficient). I am still confused why the photons can build on Bose enhancement if they are soon thermalized.