Colloquium

The Universe as a Detector: What can we learn about fundamental physics from Cosmology?

 

 

Dr. Harsh Mathur Case Western Reserve University The imprint of primordial gravitational radiation on the cosmic microwave background polarization, if observed, is considered smoking gun proof of inflation. I will discuss how such an observation can not only provide information about the Universe in the epoch of inflation but also constrain theories of grand unification. In the second part of the talk I will discuss tests of gravity on scales ranging from the tabletop to the cosmological scale. Such tests may shed light on physics beyond the standard model.

 

 

Defects with Character: Majorana Local Modes in Condensed-Matter Systems

 

 

Dr. Bertrand Halperin Harvard University Theory predicts the existence of some peculiar phases of quantum condensed matter systems that have multiple degrees of freedom with very low energy, when localized “defects” are introduced. I shall focus on a class of these phases where each defect has half of a conventional degree of freedom, and the defects may be considered as sites for localized zero-energy states of a “Majorana fermion”. Such defects would also exhibit the intriguing property of “non-Abelian statistics” -- i.e., if various defects can be moved around each other, or if two identical defects can be interchanged, the result is a unitary transformation on the quantum mechanical state that depends on the order in which operations are performed but is insensitive to many other details. In my talk, I will try to explain these various concepts and discuss the attempts to realize them in condensed matter systems.

 

 

Rapid Arctic warming and extreme weather events in mid-latitudes: Are they connected?

 

 

Dr. Jennifer Francis Rutgers University In this presentation, I will discuss the hypothesis proposed by Francis and Vavrus (2012) that links rapid Arctic warming (so-called Arctic amplification) to changes in the large-scale atmospheric circulation in the northern hemisphere that favors more persistent weather patterns and a higher likelihood of extreme weather events such as droughts, cold spells, flooding, heavy snows, and heat waves. This hypothesis has been a topic of considerable controversy in recent months, particularly regarding its relationship to the unusual weather conditions that persisted in the winter of 2013/2014. I will discuss various aspects of this linkage, what we know and don't know, and present new related research.

 

 

Science Policy in America

 

 

Dr. Tyler Glembo The American Physical Society Science Policy in America Fundamental scientific research, as a majority federally funded initiative, is becoming more deeply embedded in politics. Since the end of the Space Race, funding of basic physical sciences research as a percent GDP has continuously declined, indicating that policy makers see funding scientific research as less of a priority than they once did. Indeed, a lack of understanding about both science and how science is done amongst members of Congress has led to both reduced prioritization and also to misguided attempts at regulation, such as making peer review a public process and considering Congressional oversight for specific grants. Here we will examine a few current issues in science policy and the need for physicists to effectively weigh in on such policy issues. We will also consider the positive or negative effects such public engagement may have on our scientific careers and ways in which you can get involved.

 

 

Unravelling the Mysteries of Neutrinos

Dr. Stephen Parke Fermilab Neutrinos are the most numerous massive particles in the Universe. Their masses are very tiny, no larger than one millionth the mass of the electron. Are they like all the known massive fermions, being four component particles, or are they a new type of fermion never seen before, a two component fermion? Are there only only three neutrinos or are there more species of neutrinos? Of the three neutrinos we know of, we have determined part of the massing pattern but not the completely pattern. Also we have measured some of their mixing parameters with reasonable precision via neutrino oscillation experiments but not all. Do neutrinos violate CP in neutrino oscillations? Can neutrinos help explain the baryon-antibaryon asymmetry of the Universe? I will address many of the important questions about the neutrinos and how the future Fermilab program will address some of these questions.

 

 

Explaining the Global Warming Theory

 

 

Dr. Joseph P. Straley University of Kentucky Explaining the implications of science to contemporary public issues is an important part of our job. As an example I will give an introduction to the global warming issue.

 

 

Colloquium: Viscosity, Quark Gluon Plasma, and String Theory

Viscosity, quark gluon plasma, and string theory

Viscosity is a very old concept which was introduced to physics by Navier in the 19th century. However, in strongly coupled systems, viscosity is difficult to compute from first principle. In this talk I will describe some recent surprising developments in string theory which allow one to compute the viscosity for a class of strongly interacting quantum fluids not too dissimilar to the quark gluon plasma. I will describe efforts to measure the viscosity and other physical properties of the quark gluon plasma created in relativistic heavy ion collisions.

Cosmic Linear Accelerators: Extreme Reconnection and other Surprises from the Crab Nebula

The unexpected discovery of gamma-ray flares from the Crab Nebula may have surprising implications for plasma astrophysics. Standard particle acceleration mechanisms cannot account for the energies of the flaring photons. Instead, these observations point toward an acceleration process involving rapid destruction of magnetic field through reconnection. I will discuss the extreme particle acceleration process that may lead to the flares, and the likely role of current-driven instabilities in triggering reconnection in the Crab and elsewhere.

Colloquium: Glimpsing Color in the World of Black and White

Glimpsing color in a world of black and white

Protons, neutrons and all the many other strongly interacting subnuclear particles, known as hadrons, are made of quarks and gluons. These fundamental constituents are held together by a color force described by quantum chromodynamics (QCD). A detailed understanding of how the strong coupling regime of QCD, which is responsible for confinement and dynamical chiral symmetry breaking, determines the spectrum and structure of hadrons will be outlined. Such studies, both experimental and theoretical, color in the picture of strong dynamics. What we know now and the glimpses to come from accelerator facilities like that at Jefferson Lab will be described.

Higgs Discovery: Implications for Particle Physics - 2 Nov. 2012

The LHC has recently discovered a Higgs-like resonance with a mass of about 125 GeV. It may be the missing element of the so-called Standard Model of particle physics. This model was proposed a few decades ago, and, after the inclusion of neutrino masses, describes in an accurate way all measured observables not involving gravity. We shall discuss what are the possible implications of the Higgs Discovery for particle physics and, in particular, for theoretical and experimental physics High Energy Physics in the coming years.

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