In this talk I will discuss axion couplings to gauge bosons in 4-dimensional Grand Unified Theories and in heterotic String Theory. The topological nature of these couplings allows them to be matched from the UV to the IR, and the ratio of the anomaly with photons and gluons for any axion is fixed by unification. I will show that this implies that there is a single axion — the QCD axion — with...
We present BREAD (Broadband Reflector Experiment for Axion Detection). BREAD is a novel, scalable approach to detect meV axions using a dish antenna in high-field solenoid magnets. Several orders of axion mass around the meV range are particularly well motivated by the post-inflationary symmetry breaking scenario for the QCD axion. We present first results with BREAD prototypes, including the...
