# 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.

## Muon Capture Constraints on Sterile Neutrino Properties

Tuesday Feb 15, 2011
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We show that ordinary and radiative muon capture impose stringent constraints on sterile neutrino properties. In particular, we consider a sterile neutrino with a mass between $40$ and $80~{\rm MeV}$ that has a large mixing with the muon neutrino and decays predominantly into a photon and light neutrinos due to a large transition magnetic moment. Such a model was suggested as a possible resolution to the puzzle presented by the results of the LSND, KARMEN, and MiniBooNE experiments.

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## Dark Matter at Colliders

Friday Feb 11, 2011
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Although the fact that a large fraction of the matter in the universe is non-baryonic is beyond doubt, the exact composition of the dark matter is still shrouded in mystery. Using ultra-sensitive detectors in the deep underground laboratories, physicists are attempting to directly detect dark matter particles streaming from space. At colliders, physicists hope to manufacture large numbers of dark matter particles and study their properties. I will first use an effective field theory approach to demonstrate the power of colliders by comparing these two approaches.

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## The Search for New GeV-scale Forces

Wednesday Feb 09, 2011
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A new force mediated by a new vector boson with mass in the MeV to GeV range and with very weak coupling to ordinary matter appears naturally in many theoretical models and could also explain a variety of observed anomalies. Such anomalies include the discrepancy between the predicted and the experimentally observed value for the muon anomalous magnetic moment, and recent cosmic-ray data that can be explained by dark matter interacting through this force with ordinary matter. This talk will review the motivation for such a force and present a broad array of probes of this physics.

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## Constraints on dark matter annihilation in Milky Way halo from spherical harmonics of Fermi gamma-rays

Friday Feb 04, 2011
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Gamma-ray production by dark matter annihilation is one of the most universal indirect dark matter signals. In order to avoid intensive astrophysical background, one can study the gamma-rays away from the Galactic plane. The problems is that the dark matter annihilation signal at high latitudes is smooth and most probably subdominant to Galactic and extragalactic fluxes. I will discuss the use of spherical harmonics decomposition as a tool to distinguish a large scale small amplitude dark matter signal from astrophysical fluxes.

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## Hylogenesis and Dark Matter Induced Nucleon Decay

Tuesday Feb 01, 2011
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I discuss a new scenario called Hylogenesis (hylo=matter) that
explains the baryon and dark matter densities of Universe in a unified
way. Early universe dynamics generate the baryon asymmetry and an equal
antibaryon asymmetry in a GeV-scale hidden sector. The hidden antibaryons
are dark matter. Our model has a striking signature that dark matter can
annihilate baryons, mimicking nucleon decay. I discuss the effective
nucleon decay rates and implications for existing nucleon decay searches.

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## Deformations, bions, and (de)confinement

Friday Jan 21, 2011
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Recent observations first made in string theory led to the realization that introducing various deformations" (finite volume, appropriate

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## The Implications of like-sign dimuon anomaly

Friday Jan 14, 2011
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The D0 Collaboration recently reported a 3.2sigma deviation from the standard model prediction in the like-sign dimuon asymmetry. I will discuss the implications of this anomaly assuming that new physics contributes only to B_{d,s} mixing. The data allow universal new physics with similar contributions relative to the SM in the B_d and B_s systems, but favors a larger deviation in B_s than in B_d mixing. The general minimal flavor violation framework with flavor diagonal CP violating phases can account for the former and remarkably even for the latter case.

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## A Lee-Wick Extension of the Standard Model

Friday Dec 10, 2010
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Higher derivative extensions of the Standard Model are renormalizable but without a quadratic divergent higgs mass. Electroweak presision data constraint the scale of the higher derivatives to at least a few TeV, but then these models have no flavor problem. We skim through these and other interesting results, most remarkably causality as an emergent characteristic at long distances. But we start by explaining the indefinite metric quantization procedure proposed by Lee and Wick which is necessary for unitary.

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## Effective Conformal Theory and the Flat-space Limit of AdS

Friday Nov 19, 2010
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The idea of an effective conformal theory describing the low-lying spectrum of the dilatation operator in a CFT is developed. Such an effective theory is useful when the spectrum contains a hierarchy in the dimension of operators, and a small parameter whose role is similar to that of 1/N in a large N gauge theory. These criteria insure that there is a regime where the dilatation operator is modified perturbatively.

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## Recent Results from the CRESST dark matter search

Thursday Nov 18, 2010
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CRESST is a cryogenic dark matter search located at the Laboratori Nazionali del Gran Sasso in Italy. Scintillating CaWO4 crystals are operated as cryogenic calorimeters. The phonon (heat) signal measured with a tungten transition edge sensor on the surface of these crystals allows a precise determination of the energy deposited in the crystal, independent of the type of interaction. A light signal, simultaneously registered by a separate cryogenic detector, serves to identify the type of interaction.

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## RECENT PUBLIC LECTURE

### From the Mathematics of Supersymmetry to the Music of Arnold Schoenberg

Speaker: S. James Gates Jr.