The Status of the HAYSTAC Dark Matter Axion Search and Phase IIc Results

The axion emerged as a leading candidate for dark matter as well as the most natural solution to the Strong CP problem. The Haloscope at Yale Sensitive To Axion Cold Dark Matter (HAYSTAC) was designed as both a data pathfinder for the 4-12 GHz range and an innovation test-bed for new technologies in searching for the axion. The experiment uses a tunable microwave cavity in a strong magnetic field to search for an axion-induced power excess. HAYSTAC continues to circumvent the standard quantum limit by employing a squeezed-state receiver, the first and only such quantum enhancement scheme for an ultralight dark matter search, resulting in a factor of two improvement in scan rate. The analysis and results from the recently completed Phase IIc run for the 18.78-19.46 μeV/c² mass range will be presented.