84514
A Fluorescent Aerogel for Capture and Identification of Interplanetary and Interstellar Dust
Contemporary interstellar dust has never been analyzed in the laboratory, despite its obvious astronomical importance and its potential as a probe of stellar nucleosynthesis and Galactic chemical evolution. Here we report the discovery of a novel fluorescent aerogel that is capable of capturing hypervelocity dust grains and passively recording their kinetic energies. An array of these "calorimetric" aerogel collectors in low-Earth orbit would lead to the capture and identification of large numbers of interstellar dust grains.
117774283
Antarctic muon and neutrino detector array
73628788
Energy loss of relativistic heavy ions in matter
Abstract We have investigated the theory of energy loss of charged particles in matter due to ionization of the medium, integrating the work of other authors over several decades. We describe the most important corrections to standard energy-loss formulae. We compare our calculations to an improved measurement of the range of 1 A GeV U ions and to other codes and tabulations. We show that calculations based on the theory of ionization energy loss are at least as accurate as tabulations extrapolated from empirical data for the stopping of uranium ions in matter. We have made available the computer code resulting from our investigations.
118008749
AMANDA: Antarctic Muon And Neutrino Detector Array
Enormous detectors with unprecedented sensitivity will be required to search for astrophysical sources of neutrinos. If the transparency of deep polar ice is similar to that measured in the laboratory, then AMANDA (Antarctic Muon And Neutrino Detector Array) may be the most cost-effective way to reach the detector volumes required to search for astrophysical sources of high energy neutrinos or WIMP annihilation within the sun.
116901571
Ultrahigh-energy neutrino astrophysics with AMANDA
20884449
UNIQUE SIGNATURE OF DARK MATTER IN ANCIENT MICA
Mica can store (for >1 Gy) etchable tracks caused by atoms recoiling from WIMPs. Because a background from fission neutrons will eventually limit this technique, a unique signature for WIMPs in ancient mica is needed. Our motion around the center of the Galaxy causes WIMPs, unlike neutrons, to enter the mica from a preferred direction on the sky. Mica is a directional detector and despite the complex rotations that natural mica crystals make with respect to this WIMP ``wind,'' there is a substantial dependence of etch pit density on present day mica orientation.
119295369
The powers of monodromy
A bstractFlux couplings to string theory axions yield super-Planckian field ranges along which the axion potential energy grows. At the same time, other aspects of the physics remain essentially unchanged along these large displacements, respecting a discrete shift symmetry with a sub-Planckian period. After a general overview of this monodromy effect and its application to large-field inflation, we present new classes of specific models of monodromy inflation, with monomial potentials μ4−pϕp. A key simplification in these models is that the inflaton potential energy plays a leading role in moduli stabilization during inflation. The resulting inflaton-dependent shifts in the moduli fields lead to an effective flattening of the inflaton potential, i.e. a reduction of the exponent from a fiducial value p0 to p < p0. We focus on examples arising in compactifications of type IIB string theory on products of tori or Riemann surfaces, where the inflaton descends from the NS-NS two-form potential B2, with monodromy induced by a coupling to the R-R field strength F1. In this setting we exhibit models with p = 2/3, 4/3, 2, and 3, corresponding to predictions for the tensor-to-scalar ratio of r ≈ 0.04, 0.09, 0.13, and 0.2, respectively. Using mirror symmetry, we also motivate a second class of examples with the role of the axions played by the real parts of complex structure moduli, with fluxes inducing monodromy.
34007176
Just enough inflation: power spectrum modifications at large scales
We show that models of `just enough' inflation, where the slow-roll evolution lasted only 50- 60 e-foldings, feature modifications of the CMB power spectrum at large angular scales. We perform a systematic analytic analysis in the limit of a sudden transition between any possible non-slow-roll background evolution and the final stage of slow-roll inflation. We find a high degree of universality since most common backgrounds like fast-roll evolution, matter or radiation-dominance give rise to a power loss at large angular scales and a peak together with an oscillatory behaviour at scales around the value of the Hubble parameter at the beginning of slow-roll inflation. Depending on the value of the equation of state parameter, different pre-inflationary epochs lead instead to an enhancement of power at low l, and so seem disfavoured by recent observational hints for a lack of CMB power at l 40. We also comment on the importance of initial conditions and the possibility to have multiple pre-inflationary stages.
123231936
Higher-Dimension Operators in Higher-Dimensional Field Theories
The present thesis investigates effects of higher-dimension operators in higher-dimensional field theories. 1-loop power corrections to the gauge couplings in 5d and 6d are studied. They become calculable in the case of a softly broken grand unified theory (GUT) combined with minimal symmetry assumptions. Using the analysis of the exact quantum effective action of supersymmetric gauge theories in 5d, these power corrections are demonstrated to be the effect of higher-dimension operators. They can be unambiguously determined within 5d low-energy effective field theory. Thus, large and quantitatively controlled power-law contributions to gauge couplings arise naturally and can, in the most extreme case, lead to calculable TeV-scale power law unification. A simple 5d SU(5) model with one massless 10 in the bulk is identified where the power-law effect is exactly MSSM-like. In compactifications of 10d type IIB supergravity higher-dimension operators are an important ingredient for the stabilization of the moduli. Their cosmological impact in stabilized string vacua is analyzed and a model of inflation is constructed where these operators are essential. This model can accommodate the WMAP data of the cosmic microwave background (CMB) with a spectral index of the density fluctuations ns = 0.93. Zusammenfassung Die vorliegende Arbeit untersucht Effekte von Operatoren höherer Massendimension in höherdimensionalen Feldtheorien. Zunächst werden 1-Loop-Potenzkorrekturen zu den Eichkopplungen in 5d und 6d analysiert. Diese werden im Falle weicher Brechung einer GUT und minimaler Symmetrieannahmen berechenbar. Die Potenzkorrekturen werden dann mittels Analyse der exakten quanten-effektiven Wirkung supersymmetrischer Eichtheorien in 5d auf die Effekte von Operatoren höherer Massendimension zurückgeführt. Diese Operatoren sind durch die Eigenschaften der 5d effektiven Feldtheorie eindeutig bestimmt. Damit ergibt sich, daß diese Quantenkorrekturen zu den Eichkopplungen berechenbare ’Power-Law’Vereinigung an der TeV-Skala ermöglichen. Es wird ein einfaches 5d SU(5) GUT Modell mit einer Materie-10 im 5d ’Bulk’ beschrieben, in dem die Quantenkorrekturen exakt die Vereinigung der Eichkopplungen im MSSM imitieren. Operatoren höherer Massendimension sind in Kompaktifizierungen der 10d Typ IIB Supergravitation ein wichtiger Faktor bei der Modulistabilisierung. Die kosmologischen Implikationen dieser Operatoren werden untersucht und es wird ein Inflationsmodell konstruiert, das essentiell auf ihrer Gegenwart beruht. Dieses Modell mit einem spektralen Index der Dichtefluktuationen von ns = 0.93 ist mit den WMAP-Daten des kosmischen Mikrowellenhintergrunds verträglich.
44699983
Quantum motion of a neutron in a waveguide in the gravitational field
We study theoretically the quantum motion of a neutron in a horizontal waveguide in the gravitational field of the Earth. The waveguide in question is equipped with a mirror below and a rough surface absorber above. We show that such a system acts as a quantum filter, i.e. it effectively absorbs quantum states with sufficiently high transversal energy but transmits low-energy states. The states transmitted are determined mainly by the potential well formed by the gravitational field of the Earth and the mirror. The formalism developed for quantum motion in an absorbing waveguide is applied to the description of the recent experiment on the observation of the quantum states of neutrons in the Earth's gravitational field.
119013392
A Toy Model For Single Field Open Inflation
Inflation in an open universe produced by Coleman-De Luccia (CDL) tunneling induces a friction term that is strong enough to allow for successful small-field inflation in models that would otherwise suffer from a severe overshoot problem. In this paper, we present a polynomial scalar potential which allows for a full analysis. This provides a simple model of single-field open inflation on a small-field inflection point after tunneling. We present numerical results and compare them with analytic approximations.