# Particle Physics

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

## Seminar Series Events/Videos

May 1 2018 - 1:00pm
Room #: 394
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## Constraining a Thin Dark Matter Disk with Gaia

Tuesday Dec 12, 2017

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.

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## Thermal Relics Below an MeV

Tuesday Dec 05, 2017

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.

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## Is Self-Interacting Dark Matter Undergoing Dark Fusion?

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.

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## Using LISA-like Gravitational Wave Detectors to Search for Primordial Black Holes

Tuesday Nov 28, 2017
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Primordial black hole (PBH), which can be naturally produced in the early universe, remains a promising dark matter candidate . It can merge with a supermassive black hole (SMBH) in the center of a galaxy and generate gravitational wave (GW) signals in the favored frequency region of LISA-like experiments. In this work, we initiate the study on the event rate calculation for such extreme mass ratio inspirals (EMRI).

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## Cosmology and Signals of Strongly Interacting Dark Sectors

Tuesday Nov 21, 2017
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Standard Model particles account for a small fraction of the matter content of the universe. If the remaining dark matter (DM) was ever in thermal equilibrium with itself or with the Standard Model (SM) sector, there must exist interactions that allowed its number density to be depleted to its present value. An interesting possibility for achieving this arises in scenarios where the DM is composed of pions'' of a QCD-like dark sector.

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## TBA

Tuesday Nov 14, 2017
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Abstract TBA

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## Baryon-dark matter interactions and the radial acceleration relation

Tuesday Nov 07, 2017
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The radial acceleration relation is an empirical universal scaling relation between the total gravitational field and the Newtonian acceleration generated by baryons at any given radius within spiral galaxies. In this talk, I will discuss the possibility that such a relation arises from interactions between baryons and dark matter (DM), rather than from feedback processes or modifications of gravity. Starting from this premise, I will discuss what we can infer about the nature of baryon-DM interactions.

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## Bounds on new physics from electric dipole moments

Tuesday Oct 31, 2017
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Electric dipole moments are extremely sensitive probes for additional sources of CP violation in new physics models. The multi-scale problem of relating the high precision measurements with neutrons, atoms and molecules to fundamental parameters can be approached model-independently to a large extent; however, care must be taken to include the uncertainties from especially nuclear and QCD calculations properly. The resulting bounds on fundamental parameters are illustrated in the context of Two-Higgs-Doublet models.

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## Observation of a Gravitational Wave Emitting Neutron Star Merger with the Dark Energy Camera

Tuesday Oct 24, 2017

Motivated by the exciting prospect of new wealth of information arising from the first observations of gravitational and electromagnetic radiation from the same astrophysical phenomena, the Dark Energy Survey (DES) has performed a broad range follow-up program for LIGO/Virgo events using the Dark Energy Camera (DECam). In this talk, I present the discovery of the optical transient associated with the neutron star merger GW170817 using DECam and discuss its implications for the emerging field: multi-messenger cosmology with gravitational waves and optical data.

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## Recent results and future plans for the MAJORANA DEMONSTRATOR

Friday Oct 20, 2017
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The MAJORANA DEMONSTRATOR (MJD) is a 44-kg array of low-background germanium detectors of which 30kg is made from detectors enriched to 88% in 76Ge. MJD is operating a mile underground in the Sanford Underground Research Laboratory in Lead, SD. Its main purpose is to search for the neutrinoless double-beta decay of 76Ge and to demonstrate the technical feasibility of a tonne-scale Ge-based neutrinoless double-beta decay experiment. It is also capable of direct searches of a variety of dark matter candidates and other physics beyond the Standard Model.

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