Title: New candidates for composite dark matter

Host: Csaba Csaki

Abstract: I will discuss two subjects. One is a model of composite axion that automatically achieves a high quality Peccei-Quinn symmetry against Planck-scale corrections. It is based on standard QCD-like gauge theory, while it is made chiral to achieve Peccei-Quinn symmetry breaking by gauging part of the flavor group. It embeds Pati-Salam group so that it doubles up as the breaking mechanism of Pati-Salam group to the standard model at f_a ~ 10^11 GeV. The axion is the only gauge-neutral Nambu-Goldstone boson at this scale. It may also avoid domain walls if a mild tuning is allowed on PQ-violating operators. The other is a model of semi-annihilation. It is also based on QCD-like gauge theory where U(1)B is gauged, whose gauge boson is a dark photon. Below the confinement scale, dark pions are neutral under U(1)B, but there is a topological interaction between the dark photon and dark pions. The parameter space is bounded from all directions with a preference for a lighter mass range down to MeV. It evades constraints from indirect detection and CMB due to the P-wave nature of semi-annihilation. It may appear as “Hidden Valley” type phenomenology at LHC and future Higgs factory.