16108826
Validation of spallation neutron production and propagation within Geant4
Using simulations to understand backgrounds from muon-induced neutrons is important in designing next-generation low-background underground experiments. Validation of relevant physics within the Geant4 simulation package has been completed by comparing to data from two recent experiments. Verification focused on the production and propagation of neutrons at energies important to underground experiments. Discrepancies were observed between experimental data and the simulation. Techniques were explored to correct for these discrepancies.
22684568
MaGe-a Geant4-Based Monte Carlo Application Framework for Low-Background Germanium Experiments
We describe a physics simulation software framework, MaGe, that is based on the Geant4 simulation toolkit. MaGe is used to simulate the response of ultra-low radioactive background detectors to ionizing radiation, specifically the Majorana and Gerda neutrinoless double-beta decay experiments. Majorana and Gerda use high-purity germanium detectors to search for the neutrinoless double-beta decay of 76Ge and MaGe is jointly developed between these two collaborations. The MaGe framework contains the geometry models of common objects, prototypes, test stands and the actual experiments. It also implements customized event generators, Geant4 physics lists and output formats. All of these features are available as class libraries that are typically compiled into a single executable. The user selects the particular experimental setup implementation at run-time via macros. The combination of all these common classes into one framework reduces duplication of efforts, eases comparison between simulated data and experiment and simplifies the addition of new detectors to be simulated. This paper focuses on the software framework, custom event generators and physics lists.
22349078
Development of a data acquisition system for the MALBEK Low-Background BEGe detector
The Majorana collaboration is currently building the Majorana Demonstrator, an array of natural and en­riched high purity germanium (HPGe) detectors that will search for the neutrinoless double-beta decay of the 76Ge isotope. As part of the Demonstrator research and development effort we have deployed a prototype 450 g modified broad energy germanium (BEGe) detector at the Kimballton Underground Research Facility (KURF) in Ripplemeade, VA. This detector, the Majorana Low-Background BEGe Detector at KURF (MAL-BEK), will examine detector performance and background in the double-beta decay region of interest as well as explore the sub-keV energy spectrum in a search for light weakly interacting massive particles (WIMPs). In order to achieve this goal we have implemented a modular and highly automated data acquisition system (DAQ) capable of digitizing sub-keV signals and running autonomously in an underground environment. The DAQ is built using the Object-oriented Real-time Control and Acquisition (ORCA) application. ORCA enables the remote monitoring and control of all DAQ electronics, hardware, and slow control systems. A built in scripting language, ORCAScript, allows for the automation of run-time experimental parameters, real-time event building and data filtering, and system monitoring with email notification and alarms. The implemented MALBEK DAQ is currently operating at KURF in a production data taking mode.
15664546
Some exact results on tachyon condensation in string field theory
The study of open string tachyon condensation in string field theory can be drastically simplified by making an appropriate choice of coordinates on the space of string fields. We show that a very natural coordinate system is suggested by the connection between the worldsheet renormalization group and spacetime physics. In this system only one field, the tachyon, condenses while all other fields have vanishing expectation values. These coordinates are also well-suited to the study of D-branes as solitons. We use them to show that the tension of the D25-brane is cancelled by tachyon condensation and compute exactly the profiles and tensions of lower dimensional D-branes.
54875630
Lectures on localization and matrix models in supersymmetric Chern-Simons-matter theories
In these lectures, I give a pedagogical presentation of some of the recent progress in supersymmetric Chern–Simons-matter theories, coming from the use of localization and matrix model techniques. The goal is to provide a simple derivation of the exact interpolating function for the free energy of ABJM theory on the three-sphere, which implies in particular the N3/2 behavior at strong coupling. I explain in detail part of the background needed to understand this derivation, like holographic renormalization, localization of path integrals and large N techniques in matrix models.
14678443
Towards vacuum superstring field theory: The supersliver
We extend some aspects of vacuum string field theory to superstring field theory in Berkovits’ formulation, and we study the star algebra in the fermionic matter sector. After clarifying the structure of the interaction vertex in the operator formalism of Gross and Jevicki, we provide an algebraic construction of the supersliver state in terms of infinite–dimensional matrices. This state is an idempotent string field and solves the matter part of the equation of motion of superstring field theory with a pure ghost BRST operator. We determine the spectrum of eigenvalues and eigenvectors of the infinite–dimensional matrices of Neumann coefficients in the fermionic matter sector. We then analyze coherent states based on the supersliver and use them in order to construct higher–rank projector solutions, as well as to construct closed subalgebras of the star algebra in the fermionic matter sector. Finally, we show that the geometric supersliver is a solution to the superstring field theory equations of motion,...
18218103
Matrix model as a mirror of Chern-Simons theory
Using mirror symmetry, we show that Chern-Simons theory on certain manifolds such as lens spaces reduces to a novel class of hermitean matrix models, where the measure is that of unitary matrix models. We show that this agrees with the more conventional canonical quantization of Chern-Simons theory. Moreover, large-N dualities in this context lead to computation of all genus A-model topological amplitudes on toric Calabi-Yau manifolds in terms of matrix integrals. In the context of type-IIA superstring compactifications on these Calabi-Yau manifolds with wrapped D6 branes (which are dual to M-theory on G2 manifolds) this leads to engineering and solving F-terms for = 1 supersymmetric gauge theories with superpotentials involving certain multi-trace operators.
56086058
Unquenched flavor and tropical geometry in strongly coupled Chern-Simons-matter theories
We study various aspects of the matrix models calculating free energies and Wilson loop observables in supersymmetric Chern-Simons-matter theories on the three-sphere. We first develop techniques to extract strong coupling results directly from the spectral curve describing the large N master field. We show that the strong coupling limit of the gauge theory corresponds to the so-called tropical limit of the spectral curve. In this limit, the curve degenerates to a planar graph, and matrix model calculations reduce to elementary line integrals along the graph. As an important physical application of these tropical techniques, we study $ \mathcal{N} = 3 $ theories with fundamental matter, both in the quenched and in the unquenched regimes. We calculate the exact spectral curve in the Veneziano limit, and we evaluate the planar free energy and Wilson loop observables at strong coupling by using tropical geometry. The results are in agreement with the predictions of the AdS duals involving tri-Sasakian manifolds.