Talks

Dark matter particle interactions could imprint characteristic signals in cosmic-ray and multi-wavelength observations of the sky. The central challenge is to distinguish these signatures from similar spectra produced by standard astrophysical processes, such as the life and death of stars and the interactions of cosmic rays with interstellar material. The GAPS Antarctic balloon payload, en route for its initial flight in December 2024, is the first experiment optimized specifically for low-energy cosmic antideuterons, an essentially background-free signature of dark matter, as well as antiprotons in an unprecedented low-energy region and leading sensitivity to cosmic anithelium. In this talk, I will detail the novel GAPS detection technique, its flight instrument, and the potential impact of these measurements in the coming years. 

Claims of a low clustering amplitude (S_8) at low redshifts from weak galaxy lensing measurements trace back nearly a decade, however, recent work suggests these results may be driven by large baryonic feedback or mischaracterization of linear alignments. I will present a complimentary approach to measure the evolution of S_8(z) using spectroscopically calibrated DESI galaxies and the latest CMB lensing measurements from Planck and ACT. These data are insensitive to many of the systematic complications present in galaxy lensing measurements, while our fiducial Hybrid Effective Field Theory model robustly regulates the information obtainable from smaller scales, such that our cosmological constraints are reliably derived from the (predominantly) linear regime. Our tomographic analysis of DESI Luminous Red Galaxies (LRG) prefers a slightly lower (5 − 7%) value of S_8 than primary CMB measurements with a statistical significance ranging from 1.8 − 2.3σ. Intriguingly, our lowest redshift LRG bin is most discrepant with a Planck cosmology, leaving open the possibility that structure growth is slowing down for redshifts z < 0.5. To address this possibility, I will conclude my talk with preliminary results from the DESI Bright Galaxy Survey, which enable tomographic S_8(z) measurements over the redshift range 0.1 \lesssim z \lesssim 0.4.

We analyze the size of quantum gravity effects near black hole horizons. By considering black holes in asymptotically AdS spacetime, we can make use of the "quantum deviation" to estimate the size of quantum gravity corrections to the semiclassical analysis. We find that, in a typical pure state, corrections to correlation functions are typically of order exp(-S/2). Both the magnitude and time dependence of the correlator differ from previous results related to the spectral form factor, which estimated the correlator in a thermal state. Our results severely constrain proposals, such as non-violent unitarization and some versions of fuzzballs, that predict significant corrections to the semiclassical computation of correlation functions near black holes. We point out one possible loophole: our results rely on the standard result that bulk reconstruction is state independent for small perturbations outside the black hole.