### Conveners

#### BSM XIII

- Hongkai Liu (PITT)

In this talk we will discuss the possibility that a gauged U(1)' symmetry mediates dark matter self interactions. The breaking of this symmetry induces a Z-Z' mass mixing term, connecting the dark and visible sectors. After symmetry breaking of the U(1)', the fermion content of the dark sector is divided into right handed neutrinos and a stable dark matter candidate. We discuss the neutrino...

We explore the neutrino sector of the minimal left-right symmetric model, with the additional charge conjugation discrete symmetry, in the novel regime where type-I and type-II seesaw mechanisms are equally responsible for the light neutrino masses, which can result in large active-sterile mixing. We show that unless the charged lepton mixing matrix is the identity and the right handed...

The origin of Majorana neutrino masses in a Majoron model provide a well-motivated scenario for the generation of identifiable primordial stochastic background of gravitational waves. In this talk I will discuss how a spectrum with a joint contribution both from a strong first order phase transition and from global cosmic strings can emerge naturally in these models. Moreover, the interplay...

Black hole superradiance is a phenomenon in which, purely through gravitational interactions, light bosons are spontaneously produced outside spinning black holes. Through this effect, an exponentially growing Bose-Einstien condensate cloud forms around the black hole. In the case of dark photon superradiance, the cloud can form into strings of magnetic flux analogous to Abrikosov vortices in...

I will describe the collider phenomenology of near-continuum dark matter, a model that gives rise to a gapped tower of Kaluza-Klein (KK) states. The model is coupled to the Standard Model via a Z-portal coupling, and the unique experimental signatures of this model include a cascade decay with large displaced vertices, a characteristic fermion energy spectrum, and more, all of which will be...