Particle Physics

This series consists of talks in the areas of Particle Physics, High Energy Physics & Quantum Field Theory.

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.
 

 

Thursday Jun 07, 2018
Speaker(s): 

The power spectrum for fluctuations in the number density of galaxies can be very different in shape from the power spectrum for fluctuations in the mass density at very small wave vectors (i.e., large length scales) if the primordial density fluctuations are non-Gaussian. I review this phenomena. (It  is fairly well known in the more astrophysical part of the cosmology community but less so in the particle physics part of the field.) Then I show that primordial non-Gaussianities that arise from quantum loop diagrams in de-Sitter space can give rise to this phenomena.

Collection/Series: 
Scientific Areas: 
 

 

Tuesday Jun 05, 2018
Speaker(s): 

We present fundamental limits of axion and hidden-photon dark matter searches probing the electromagnetic coupling. These limits are informed by constraints on noise in phase-insensitive amplifiers, as well as constraints on impedance matching. We motivate the use of quantum-limited amplifiers for dark matter searches, in particular at low masses/frequencies, where they provide a substantial enhancement due to sensitivity outside of the detector bandwidth. We discuss the role of priors, e.g.

Collection/Series: 
Scientific Areas: 
 

 

Tuesday May 29, 2018
Speaker(s): 
Collection/Series: 
Scientific Areas: 

 

Tuesday May 08, 2018
Speaker(s): 

Ultralight bosons exist in various proposed extensions to the Standard Model, which can form condensates around rapidly rotating black holes through a process called superradiance. These boson clouds have many interesting observational consequences, such as the continuous emission of monochromatic gravitational waves.

Collection/Series: 
Scientific Areas: 
 

 

Tuesday May 01, 2018
Speaker(s): 

Microwave Kinetic Inductance Detectors, or MKIDs, are superconducting detector arrays that can measure the energy and arrival time of individual optical through near-IR photons without read noise or dark counts.  I will discuss our recent work and results from the first two MKID Integral Field Spectrographs (IFSs) for high contrast imaging, DARKNESS/SDC at the P

Collection/Series: 
Scientific Areas: 
 

 

Friday Apr 27, 2018
Speaker(s): 

I show that dark matter abundance can be set by the decoupling of inelastic scatterings instead of annihilations. Coscattering points to dark matter that is exponentially lighter than the weak scale and has a suppressed annihilation rate, avoiding constraints from indirect detection. The late decays of the states into which dark matter upscatters, can lead to observable distortions to the blackbody spectrum of the cosmic microwave background. 

Collection/Series: 
Scientific Areas: 

 

Tuesday Jan 16, 2018
Speaker(s): 

I will discuss the calculation of the axion dark matter relic abundance produced by strings and domain walls in the early universe. These objects appear if the global symmetry that the axion is associated with is unbroken at the end of inflation, and in this scenario there is, in principle, a unique prediction for the axion dark matter mass. I will present results from numerical simulations that indicate that the density of strings may be significantly larger than previously thought, leading to a corresponding change in the required axion dark matter mass.

Collection/Series: 
Scientific Areas: 

 

Tuesday Dec 12, 2017
Speaker(s): 

If a component of the dark matter has dissipative interactions, it could collapse to form a thin dark disk in our Galaxy coincident with the baryonic disk. It has been suggested that dark disks could explain a variety of observed phenomena, including periodic comet impacts. Using the first data release from the Gaia mission, we search for a dark disk via its effect on stellar kinematics in the Milky Way. I will present new limits on the presence of a thin dark matter disk, as well as measurements on the matter density in the solar neighborhood.

Collection/Series: 
Scientific Areas: 

 

Tuesday Dec 05, 2017
Speaker(s): 

I will discuss a class of models in which thermal dark matter is lighter than an MeV. If dark matter thermalizes with the Standard Model below the temperature of neutrino-photon decoupling, constraints from measurements of the effective number of neutrino species are alleviated. This framework motivates new experiments in the direct search for sub-MeV thermal dark matter and light force carriers.

Collection/Series: 
Scientific Areas: 

 

Friday Dec 01, 2017

We suggest that two-to-two dark matter fusion may be the relaxation process that resolves the small-scale structure problems of the cold collisionless dark matter paradigm. In order for the fusion cross section to scale correctly across many decades of astrophysical masses from dwarf galaxies to galaxy clusters, we require the fractional binding energy released to be greater than v^n ~ [10^{-(2-3)}]^n, where n=1,2 depends on local dark sector chemistry.

Collection/Series: 
Scientific Areas: 

Pages