College of Arts and Sciences

The Cryogenic Dark Matter Search (CDMS) is searching for Weakly Interacting Massive Particles (WIMPs) with cryogenic germanium particle detectors. These detectors discriminate between nuclear recoil candidate and electron recoil background events by collecting both phonon and ionization energy from recoils in the detector crystals. The CDMS II experiment has completed analysis of the first data run with 30 semiconductor detectors at the Soudan Underground Laboratory resulting in a world leading WIMP-nucleon spin-independent cross section limit for WIMP masses above 44 GeV/c2. As CDMS aims to achieve greater WIMP sensitivity, it is necessary to increase the detector mass and discrimination between signal and background events.

Continue reading… Cryogenic Dark Matter Search . Current Results and Future Background Discrimination – Cathy Bailey

The dynamics of relativistic current carrying string loops moving axisymmetrically on the background of a Kerr black hole are characterized. In one interesting type of motion, a loop can be ejected along the axis, some internal elastic or rotational kinetic energy being converted into translational kinetic energy.

Continue reading… String shots from a spinning black hole – Ted Jacobson

In this introductory lecture I will present why we have built the LHC, and discuss the underlying physics of a hadron collider. This includes the fundamentals of QCD (the theory for the strong interaction), features such as jets and hadronization, and an introduction to the physics of the Standard Model, including Electroweak symmetry breaking. The lecture will be concluded with a discussion about the problems with the Standard Model.

Continue reading… Fundamentals of the LHC – Johan Alwall

The inflationary paradigm has become one of the most compelling candidates to explain the observed cosmological phenomena. However, the data is still inconclusive about the particular details of the inflationary model. Apart from the basic, single field model, there exists a wide range of currently undistinguishable possibilities for the scalar field number, potential and couplings during the early universe. In this talk I will review one of these extensions of the basic inflationary model, the curvaton model, where at least two scalar fields are present during inflation. I will revisit the constraints on the parameters of the model in light of the results of recent non-Gaussianity analyses and bounds on the cold dark matter isocurvature contribution in the primordial anisotropies of the CMB.

Continue reading… The curvaton inflationary model, non-Gaussianity and isocurvature – Maria Beltran

Cosmic acceleration may be due to modifications of general relativity (GR) at large scales, rather than dark energy. We use analytic techniques and N-body simulations to find out what observational signatures to expect in brane-induced gravity, with focus on new nonlinear effects not present in GR.

Continue reading… Large-Scale Structure in Modified Gravity – Roman Scoccimarro

We have proposed that the first phase of stellar evolution in the history of the Universe may be Dark Stars (DS), powered by dark matter heating rather than by nuclear fusion. Weakly Interacting Massive Particles, which may be their own antipartners, collect inside the first stars and annihilate to produce a heat source that can power the stars. A new stellar phase results, a Dark Star, powered by dark matter annihilation as long as there is dark matter fuel, with lifetimes from millions to billions of years. We find that the first stars are very bright (a million times solar) diffuse puffy objects during the DS phase,

Continue reading… Dark Stars – Katie Freese

Cascading gravity is an explicit realization of the idea of degravitation, where gravity behaves as a high-pass filter. This could explain why a large cosmological constant does not backreact as much as anticipated from standard General Relativity. The model relies on the presence of at least two infinite extra dimensions while our world is confined on a four-dimensional brane. Gravity is then four-dimensional at short distances and becomes weaker at larger distances.

Continue reading… Cascading Gravity and Degravitation – Claudia de Rham

Simplest models of the Universe predict global (statistical) isotropy on large scales in the observable Universe. However there are a number of interesting models that predict existence of preferred directions. In this talk I will present results of using CMB anisotropy maps to test the global isotropy of the Universe on its largest scales, and will show how that can help us constrain interesting models such as topology of the Universe and anisotropic cosmological models (e.g. Bianchi models). I will also discuss the intriguing lack of power on large angular scales in the observed CMB maps and implications that it may have for cosmology.

Continue reading… Testing global isotropy and some interesting cosmological models with CMB – Amir Hajian

We examine hilltop quintessence models, in which the scalar field is rolling near a local maximum in the potential, and w is close to -1. We first derive a general equation for the evolution of the scalar field in the limit where w is close to -1. We solve this equation for the case of hilltop quintessence to derive w as a function of the scale factor; these solutions depend on the curvature of the potential near its maximum. Our general result is in excellent agreement (delta w < 0.5%) with all of the particular cases examined. It works particularly well (delta w <

Continue reading… Hilltop Quintessence – Sourish Dutta

Observations by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite have identified an excess of microwave emission from the centre of the Milky Way. It has been suggested that this {\it WMAP haze} emission could potentially be synchrotron emission from relativistic electrons and positrons produced in the annihilations of one (or more) species of dark matter particles. In this paper we re-calculate the intensity and morphology of the WMAP haze using a multi-linear regression involving full-sky templates of the dominant forms of galactic foreground emission, using two different CMB sky signal estimators. The first estimator is a posterior mean CMB map,

Continue reading… Can the WMAP Haze really be a signature of annihilating neutralino dark matter? – Daniel Cumberbatch

I will talk about two inflationary scenarios in which the cooperative behavior of multiple branes give rise to inflation. In the first one, which we call cascade inflation, assisted inflation is realized in heterotic M-theory and by non-perturbative interactions of N M5-branes. The features in the inflaton potential are generated whenever two M5-branes collide with the boundaries. The derived small-scale power suppression could serves as a possible explanation for the dearth of observed dwarf galaxies in the Milky Way halo. In the second one, the transverse dimension of coincident D3-branes, which are N-dimensional matrices, result in inflation. We discuss how various scenarios such as chaotic,

Continue reading… Multi-brane Inflation in String Theory – Amjad Ashoorioon

Five important milestones have been achieved in high energy heavy ion collisions utilitizing the Relativistic Heavy Ion Collider at BNL: – a new phenomena – which was proven to signal a new state of matter – this state of matter was found to be a perfect fluid, with temperatures reaching 2 terakelvins and more – the degrees of freedom were shown to be the quarks – and the kinematic viscosity of this matter at extemely high temperatures were found to be less than that of a superfluid 4He at the onset of superfluidity. I will summarize these milestones and some more recent novel results of the RHIC programme and also outline an interesting new direction,

Continue reading… High temperature superfluidity in high energy heavy ion collisions at RHIC and forward physics with TOTEM at LHC – Tamas Csorgo

TBA

Continue reading… Anthropy and entropy – Irit Maor

Despite the successes of modern precision cosmology to measure the macroscopic properties of dark matter, its microscopic nature still remains elusive. LHC is expected to probe energies relevant for testing theories of electroweak symmetry breaking, and as a result may allow us to produce dark matter for the first time. Other indirect experiments, such as PAMELA, offer additional ways to probe the microscopic nature of dark matter through observations of cosmic rays. Results from a number of indirect detection experiments seem to suggest that our old views of the creation of dark matter may need revisited. This is also suggested by theories of electroweak symmetry breaking that are required to be well behaved at high energies and in the presence of gravity.

Continue reading… On the Challenge to Unveil the Microscopic Nature of Dark Matter – Scott Watson

The South Pole Telescope recently discovered three new galaxy clusters in their CMB maps via the Sunyaev Zel’dovich (SZ) effect (Staniszewski et al. 2008). These are the first galaxy clusters discovered using this promising new technique. The number of galaxy clusters at a given redshift depends strongly on the expansion history of the universe as well as the relative abundances of matter, dark matter and dark energy during structure formation. The brightness of the SZ signal from a galaxy cluster is nearly redshift independent, making it a powerful tool for discovering galaxy clusters that were forming when dark energy was becoming important.

Continue reading… South Pole Telescope: From conception to first discovery – Zak Staniszewski

The near-absence of primordial nongaussianity is one of the basic predictions of slow roll, single-field inflation, making measurements of nongaussianity fundamental tests of the physics of the early universe. I first review parametrizations of nongaussianity and briefly review the history of its measurements from the CMB and large-scale structure. I then present results from recent work where effects of primordial nongaussianity on the distribution of largest virialized objects was studied numerically and analytically. We found that the bias of dark matter halos takes strong scale dependence in nongaussian cosmological models. Therefore, measurements of scale dependence of the bias, using various tracers of large-scale structure,

Continue reading… Primordial Nongaussianity and Large-Scale Structure – Dragan Huterer

Cool white dwarf stars are among the oldest objects in the Galaxy. These relics of an ancient stellar population offer a window into the early stages of the galaxy and its formation, and more data on the oldest and coolest white dwarfs may help resolve the interpretation of microlensing searches for MACHOs in the galactic halo. The Sloan Digital Sky Survey (SDSS) and the SEGUE program of SDSS-II are ideally suited to a search for these rare objects, and to date we have discovered 13 new ultracool white dwarfs =96 those with temperatures below 4000K =96 constituting the majority of these faint stellar fossils.

Continue reading… In Search of the Coolest White Dwarfs – Evalyn I.Gates

For a decade, the PEP-II/BaBar B-factory has been a flagship experiment in precision measurements in the flavor sector, notably in the decays of B and charm mesons. Before its shutdown in April, the B-factory took a new direction and secured the world’s largest samples of Upsilon(3S) and Upsilon(2S) mesons and performed an extensive scan above the Upsilon(4S) resonance. I will talk about the motivation for this change of course and our new results in both the search for the ground state of bottomonium and the search for evidence of new physics at a low mass scale, including both the Higgs and dark matter.

Continue reading… The White Elephant: Upsilon Physics at the BaBar B-factory – Steve Sekula

Dark energy is parameterized by the time evolution of its equation of state $w(z)$. For a very wide class of quintessence (and phantom) dark energy models, we parameterize $w(z)$ with physical quantities related to the scalar field potential and initial conditions. Using a set of updated observational data including supernova, CMB, galaxy power spectrum, weak lensing and Lyman-${\alpha}$ forest, we run Markov Chain Monte Carlo calculations to determine the likelihood of cosmological parameters including the new dynamical parameters. The best fit model is centered around the cosmological constant (flat potential), while many popular scalar field models are excluded at different levels.

Continue reading… Parameterizing dark energy – Zhiqi Huang

If much of the dark matter in the Universe consists of WIMPs, their annihilation releases energy, some of which ionizes the IGM. We calculate the contribution to the optical depth due to particle annihilation in early halos. This allows us to place bounds on the dark matter particle mass. We also consider the effect of halos on the H21 cm background. It is shown that larger halos (~ 10^6 solar masses) contain enough hot Hydrogen gas to produce a measurable H21 cm background. We present our conclusions.

Continue reading… The effect of dark matter halos on reionization and the H21 cm line – Aravind Natarajan