### Dec 09-13, 2013, Time 10 am - 5 pm, Place PHYS 4102

Micro-Workshop: "Subtle bumps at the LHC" (Click on the link for more information.)

### Monday, Dec 09, 2013, 3:00pm- 4:00pm, Room 4102, Physics Building

Particle Theory Seminar: "Pure Gravity Mediation"

Jason Evans, University of Minnesota

### Wednesday, Dec 11, 2013, 1:30pm- 3:00pm, Room 4102, Physics Building

Gravity Theory Seminar:"Density perturbations in Hybrid Inflation"

### Thursday, Dec 12, 2013, 1:30 pm - 2:30 pm, Room 4102, Physics Building (Notice the difference from usual day)

Nuclear Theory Seminar:"Neutron-Antineutron transitions from the Lattice"

Michael Buchoff, University of Washington

4/10/13 Dam Son, University of Chicago

Title: "Newton-Cartan geometry and the effective field theory of the quantum Hall states"

Abstract: A nonrelativistic system in an external metric exhibits a gauge version of Galilean invariance. This symmetry put constraints on the effective field theory of quantum Hall states. We describe how the effective field theory satisfying these constraints can be constructed using the formalism of the Newton-Cartan geometry. Physical consequences for electromagnetic response at nonzero wavenumbers are derived.

2/27/13 James Lattimer, State University of New York at Stony Brook

Title: "A Convergence on an Understanding of the Dense Matter Equation of State"

Abstract: Determining the equation of state of neutron star matter has been a long-sought goal. Recently, there has been a remarkable convergence in our understanding of dense matter from several directions: multiple nuclear experiments, theoretical neutron matter studies, pulsar mass determinations, and estimates of neutron star masses and radii from X-ray sources. The key parameters are related to the symmetry energy of matter near the nuclear saturation density, which is closely related to the neutron star mass-radius relation. Observations indicate that the maximum neutron star mass is in excess of 2 solar masses, and, together with nuclear experimental and theoretical studies, restrict the radii of neutron stars with approximately 1.4 - 1.5 solar masses to lie in the range 11 to 12.5 km. In addition, the rapid cooling recently found for the neutron star in the Cassiopeia supernova remnant indicates that both neutron superfluidity and proton superconductivity exist in its interior, and tightly constrain their respective critical temperatures.

9/20/12 Alberto Nicolis,Columbia University

Title: "Effective field theories for fluids and superfluids"

Abstract: I will present a novel field theoretical framework that captures the long-distance and low frequency dynamics of hydrodynamical systems. The approach is that of effective field theories, whose building blocks are the infrared degrees of freedom and symmetries. Possible applications include questions in condensed matter physics, heavy-ion collisions, astrophysics and cosmology, and quantum hydrodynamics. Moreover, this formulation naturally invites (and answers) new questions in classical hydrodynamics.

10/9/12 James Hartle,University of California, Santa Barbara

Title: "The Quantum State of the Universe"

Abstract: If the universe is a quantum mechanical system then it has a quantum state. A theory of that state is a necessary part of any final theory that makes predictions for the large scale features of the universe that we observe today. This talk will focus one particular theory of the quantum state --- Hawking's no-boundary wave function of the universe. We will concentrate summarizing the current situation of its predictions for such large scale features of the universe as classical spacetime, inflation, the arrows of time, the CMB spectrum, the existence of isolated systems, the number of time dimensions, and the topology of space.

11/8/12 Marc Kamionkowski,Johns Hopkins University

Title: "Covering the bases"

Abstract: One of the principal aims of cosmology today is to seek subtle correlations in primordial perturbations, beyond the standard two-point correlation that has been mapped precisely already, that may hint at new physics beyond that in the simplest single-field slow-roll models. I will describe in this talk a new class of such correlations and how they may be sought with galaxy surveys and in the CMB. I will then turn my attention to a new formalism, total-angular-momentum (TAM) waves, that my collaborators and I have recently developed. In most of the literature, cosmological perturbations are decomposed into Fourier modes, or plane waves. However, for calculations that aim to produce predictions for angular correlations on a spherical sky, a decomposition into TAM waves provides a far more direct and intuitive route from theory to observations. I will describe the formalism and illustrate its utility with a few sample calculations.

9/29/2011 Sergei Dubovsky, New York University

Title: "Exploring the String Axiverse with Astrophysical Black Holes?"

Abstract: Combining the QCD axion as a solution to the strong CP problem with the properties of axions in string theory suggests the simultaneous presence of many ultralight axions with masses homogeneously distributed over the log scale---the "Axiverse". These axions give rise to a number of distinctive observational signatures, including the rotation of the CMB polarizations at the level within the reach of the Planck satellite, and steps in the dark matter power spectrum. A surprising evidence for the axions with masses in the range 10^(-22) to 10^(-10) eV may come from observations of astrophysical black holes through the Penrose superradiance process. When the axion Compton wavelength is of order of the black hole size, the axions develop "superradiant" atomic bound states around the black hole "nucleus". Their occupation number grows exponentially by extracting rotational energy from the ergosphere, culminating in a rotating Bose-Einstein axion condensate emitting gravitational waves. This mechanism creates mass gaps in the spectrum of rapidly rotating black holes and gives rise to a distinctive gravity wave signal. In particular, the QCD axion with the decay constant of order the GUT scale affects the dynamics of stellar mass black holes. This opens a possibility for a discovery of the QCD axions through ongoing measurements of black hole spins. The corresponding gravity wave signal may be within the reach of the Advanced LIGO.

9/9/2010 Gordan Kane, University of Michigan

Title: "String theory and the real world"

Abstract: In this talk I'll describe how string theory is exciting because it can address most or all of the questions we hope to understand about the quarks and leptons that make up our world, the forces that form our world, cosmology, CP violation, and more. I’ll explain why string theory is testable in basically the same ways as the rest of physics, and why much of what is written about that is misleading. String theory is already or soon being tested in several ways, including dark matter, LHC physics, neutrino physics, cosmological history, and more, from work in the increasingly active subfield "string phenomenology

3/4/2010 Tom Appelquist, Yale University

Title: "TeV Physics and Conformality"

Abstract: I will review the possible role of conformal symmetry in developing viable theories of new physics at the TeV scale and beyond. Since strongly coupled gauge theories may describe this new physics, it is natural to employ lattice-based numerical simulations as in QCD. I will describe recent work along these lines and discuss prospects for future progress.

4/29/2010 Michel Janssen, University of Minnesota

Title: "Jordan and the wave-particle duality of light"

Abstract: In 1909, Einstein derived a formula for the mean-square energy fluctuation in black-body radiation. This formula is the sum of a wave term and a particle term. In a famous joint paper with Born and Heisenberg submitted in late 1925, Pascual Jordan used the new matrix mechanics to show that one recovers both these terms in a simple model of quantized waves. This result not only solved Einstein's puzzle about the wave-particle duality of light, it also provided striking evidence for matrix mechanics and a strong argument for field quantization. After reviewing Einstein's early work on fluctuations in black-body radiation, I present Jordan's result and the curious story of its reception. Rather than being hailed as a major contribution to quantum theory, Jordan's result met mostly with skepticism, even from his co-authors. I will argue that the skeptics were wrong.

Based on: A. Duncan and M. Janssen, "Pascual Jordan's resolution of the conundrum of the wave-particle duality of light." Studies in History and Philosophy of Modern Physics 39 (2008): 634-666.

4/1/2010 Stefano Profumo, University of California, Santa Cruz

Title: "Cosmic Rays and the Quest for New Physics"

Abstract: Recent cosmic ray data, notably from the Pamela and Fermi satellites, indicate that previously unaccounted-for powerful sources in the Galaxy inject high-energy electrons and positrons. Interestingly, this new source class might be related to new fundamental particle physics, and specifically to pair-annihilation or decay of galactic dark matter. I will discuss how this exciting scenario is constrained by Fermi gamma-ray observations, and which astrophysical source counterparts could also be responsible for the high-energy electron-positron excess. In particular, I will review the case for nearby mature pulsars, and the impact of newly discovered radio-quiet pulsars that pulsate in gamma rays. While high-energy electron-positron measurements sample local (closer than 1 kpc) cosmic rays, diffuse radio and gamma-ray emission informs us about the global galactic cosmic ray population. I will thus offer a few thoughts on recent claims involving the detection of diffuse radio ("WMAP haze") and gamma-ray ("Fermi haze") emissions and on implications for the quest for New Physics

10/1/2009 Michael Ramsey-Musolf, University of Wisconsin, Madison

Title: “Electroweak Baryogenesis: Theoretical Progress and Experimental Tests”

Abstract: Explaining the origin of the visible matter of the universe is one of the outstanding problems at the interface of particle and nuclear physics with cosmology. It is possible that new physics at the electroweak scale my provide the necessary ingredients for successful baryogenesis. In this talk, I discuss recent theoretical developments in electroweak baryogenesis and their implications for experimental tests using both "table top" searches for permanent electric dipole moments and collider searches for new particles.

4/10/2009 Edward Shuryak, SUNY, Stony Brook

Title: “Strongly coupled quark-gluon plasma”

Abstract: Experiments made at the Relativistic Heavy Ion Collider suggest a new phase of QCD, known as the quark-gluon plasma, to be a near-perfect liquid with small viscosity. The first 1/3 of the talk is about the main phenomena which lead to this conclusion. The next 2/3 is about attempts to explain it. One is based on electric-magnetic duality and the role of (color) magnetically charged quasiparticles -- monopoles and dyons. Another duality is the so called AdS/CFT correspondence, based on string theory gravity methods, which allows to address strongly coupled gauge theories. Two transport observables -- the diffusion constant and viscosity -- obtained in both ways will be compared at the end.

3/27/2009 Paul Steinhardt, Princeton University

Title: “Endless universe”

Abstract: An introductory discussion of the inflationary and cyclic models of the universe, including connections to observations past and future.

3/13/2009 Christian Bauer, Lawrence Berkeley National Laboratory

Title: “NLO calculations and parton showers”

Abstract: Many inclusive processes relevant for collider physics have by now been calculated to NLO accuracy. Unfortunately, fully exclusive event samples are required by the experimental collaborations in order to implement experimental cuts and correct the theoretical predictions for detector effects. In this talk, I will describe how to combine NLO calculations with parton shower algorithms and will explain why resummed NLO calculations are necessary. I will present results that allow this combination to be performed without the need for computationally costly numerical integrations.

2/13/2009 Robert Myers, Perimeter Institute

Title: “Rheology and the quark-gluon plasma”

Abstract: In recent years, experiments have discovered an exotic new state of matter known as the strongly coupled quark-gluon plasma (sQGP), which seems to behave like a nearly perfect fluid. In parallel developments, string theory has provided a theoretical laboratory for studying the hydrodynamic properties of plasmas in certain strongly interacting gauge theories. I will describe efforts to measure the physical properties of the sQGP and the possible connections to the string theory calculations.

11/7/2008 Maxim Pospelov, University of Victoria and Perimeter Institute

Title: “Catalysis of Primordial Nucleosynthesis”

Abstract: About 1000 seconds after the Big Bang the nuclear reactions between primordial protons and neutrons led to the formation of light nuclei, such as deuterium, helium and lithium. This epoch is known as the Big Bang Nucleosynthesis (BBN) and is well described by the combination of general relativity, quantum mechanics and particle/nuclear physics. Theoretical prediction of elemental abundances are confronted with observations, providing an important test of modern cosmology. In this talk, I explain how the nonstandard particle physics (such as e.g. supersymmetric particles) may alter the outcome of primordial nuclear reactions leading to detectable consequences. I introduce the concept of Catalyzed BBN, and show that heavy metastable charged particles can completely change lithium abundance, providing an important test of many particle physics models, and perhaps helping to resolve existing puzzles with lithium abundance.

10/24/2008 Mithat Unsal, SLAC and Stanford University

Title: “Topological symmetry and (de)confinement in gauge theories and spin systems”

Abstract: The non-perturbative dynamics of non-supersymmetric QCD-like and chiral gauge theories remained largely elusive despite much effort over the years. Recently, novel techniques (such as center stabilizing double trace deformations) which allow us to coninuously connect the physics of these gauge theories on R^4 to very small S^1 \times R^3 are found. In most cases, the physics of small S^1 is analytically tractable. The types of topological excitations that appear in this window are far richer than anticipated earlier. For example, a type of composite referred as magnetic bion with net magnetic charge +2 is responsible for the appearance of a mass gap in large class of QCD-like theories. What makes this excitation interesting is also an exotic mechanism of pairing, induced by fermions. Some of these techniques also find useful applications to two dimensional frustrated spin-systems. In this talk, I will give an elementrary introduction to the world of gauge theories through this window.

10/10/2008 Avi Loeb, Institute for Theory and Computation (ITC), Harvard University

Title: “Exploring new physics in the early universe and around black holes”

Abstract: The Universe offers environments with extreme physical conditions that cannot be realized in laboratories on Earth. These environments provide unprecedented tests for extensions of the Standard Model. I will describe two such "astrophysical laboratories", which are likely to represent new frontiers in observational astrophysics over the next decade. One provides a novel probe of the initial conditions from inflation and the nature of the dark matter, based on 3D mapping of the distribution of cosmic hydrogen through its resonant 21 cm line. The second allows to constrain the metric around supermassive black holes based on direct imaging or the detection of gravitational waves. I will describe past and future observations of these environments and some related theoretical work.

9/26/2008 Christopher Herzog, Princeton University

Title: “Holographic superfliuidity and superconductivity”

Abstract: I will describe a simple gravitational model in 3+1 dimensions that is dual to a strongly interacting field theory in 2+1 dimensions with remarkable properties. The gravity model consists of a charged black hole that acquires scalar hair when the Hawking temperature becomes sufficiently low. The gravitational instability is dual to a phase transition in the field theory between a normal and a superconducting (or superfluid) state. From the gravity model, we calculate the thermodynamic and transport properties of the field theory, yielding intringuingly familiar results. These methods hold promise for understanding strongly interacting real world condensed matter systems.

9/12/2008 Aneesh Manohar, UC San Diego

Title: “Electroweak corrections at LHC energies”

Abstract: The theory of radiative corrections to high energy scattering processes, found in field theory textbooks, is briefly reviewed. These corrections can be obtained more efficiently by using soft-collinear effective theory. This allows one to compute electroweak radiative corrections in the standard model due to W and Z exchange. At LHC energies, these particles are essentially massless, and the electroweak corrections are large, changing the cross-section by 25-40%. The results apply to the basic LHC scattering processes such as jet production and Drell-Yan. The corrections are typically not included in standard parton shower Monte-Carlos.

4/24/2008 W. G. Unruh, University of British Columbia

Title: “Where do the particles come from?”

4/3/2008 Richard Easther, Yale University

Title: “The Observational Fingerprints of Inflation”

3/13/2008 Alex Maloney, McGill University

Title: “Phases of Quantum Gravity in Three Dimensions”

2/14/2008 Juan Maldacena, Institute for Advanced Study

Title: “AdS/CFT duality: recent developments”

12/12/2007 Nima Arkani-Hamed, Harvard University

Title: “Possible and Impossible in Quantum Gravity”

10/17/2007 Dragan Huterer, University of Michigan

Title: “Cosmological Probes of Dark Energy”

Abstract: One of the great mysteries of modern cosmology is the origin and nature of dark energy - a smooth component that contributes about 75% of the total energy density in the universe and causes its accelerated expansion. Although discovered less than a decade ago, dark energy domination has recently been confirmed via several independent cosmological probes; nevertheless, there are no good theoretical leads as to its physical provenance. In this talk I examine critically various approaches to measure the macroscopic properties of dark energy, and describe accurate yet general methods to model the expansion history of the universe in the presence of dark energy. I discuss the importance of controlling the systematic errors in upcoming surveys, and show examples from some recent work. Finally, I review upcoming surveys specifically designed to help understand the origin and physical nature of dark energy.

9/19/2007 Dam Son, University of Washington

Title: “Viscosity, Black Holes, and Relativistic Heavy Ion Collisions”

Abstract: Viscosity is a very old concept which was introduced to physics by Navier in the 19th century. However, in strongly coupled systems viscosity is extremely difficult to compute ab initio. In this talk I will describe some recent surprising developments in string theory which allow one to compute, easily and conveniently, the viscosity in a class of strongly interacting relativistic quantum field theories. I will describe efforts to measure the viscosity and other physical properties of the quark gluon plasma created at the Relativistic Heavy Ion Collider, and mention possible connections to the string-theory calculations.