Tuesday, 13 October 2015

CosPA 2015 Liveblog: Day Two Session Four

I spend yet another parallel session in the same room.  And wonder why they are so opposed to turning on the AC.
4:00 pm: Oscillating Asymmetric Sneutrino Dark Matter from the Maximally U(1)L Supersymmetric Inverse Seesaw, Zhaofeng Kang

Oscillating ADM: ADM without an asymmetry.  That is, would-be asymmetric charge is not exact; e.g. U(1)L symmetry broken by a Majorana mass for a mostly-Dirac fermion. This small breaking mixes the DM/anti-DM.

Inverse see-saw uses small neutrino Majorana mass.  Thus involves small breaking of lepton number.  In SUSY context, means sneutrino will oscillate if it is LSP.

4:25 pm: Self-Interacting Dark Matter from a Non-Abelian Hidden Sector, Tim Tait

Small scale structure: galaxy clusters.  Specifically, we are talking about the cusp problem: density profiles seem to be cored rather than cuspy as predicted by numerical simulations.  I'm writing a post on this I'll hopefully have done this weekend.  A similar thing shows up in small spiral galaxies.  Also the missing satellite/too-big-to-fail problem.  Worth noting that Bullet cluster constraints are likely not as strong as naively thought, as those constraints assume NFW profiles.

So we look to fix this using SIDM.  The challenge is that the interaction strength is large for WIMPs; comparable to neutron scattering cross sections.  Thus we are motivated to consider dark SU(N).  Specifically we consider pure Yang-Mills, and the theory at low energies consists of glueballs.

Calculations can be somewhat done on lattice, but for now use parametric scaling/NDA.  Worth noting that large N will turn off interactions.  For not-large N, get a confining scale of ~ 500 MeV.  Also need to take into account possibly different temperatures in hidden/visible sectors.  Need Th ~ 0.01 Tvis.

Simple extension of theory involves adding a Majorana adjoint.  If heavy compared to confining scales, get glueballino states.  These are strongly interacting by glueball exchange.  Things work for MeV confinement and multi-TeV glueballinos.

4:50 pm: Galactic Centre excess by Higgs portal dark matter, Osamu Sato

Type X two Higgs doublet model, annihilations to taus.

5:15 pm: Electroweak Baryogenesis with Anomalous Higgs Couplings, Archil Kobakhidze

I'm out of power and don't have a socket nearby, so we'll have to pass on this talk.

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