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Gauge invariance in 2Pi effective actions

Description: (Abstract damaged) The 2PI (two particle irreducible) effective action is a general field theoretic tool for addressing this problem. In constructing it one introduces sources for both the fields and their two-point bilinears.
Date: January 1, 2003
Creator: Mottola, E. (Emil)
Partner: UNT Libraries Government Documents Department

Research highlights for the period February 1, 1982-July 31, 1982

Description: Progress is briefly described on the following topics: (1) study of rare muon induced reactions, (2) measurement of ..pi../sup -/p ..-->.. n + ..gamma.. and search for the eta/sub c/, (3) production of high-mass dimuons by pions, (4) production of high mass ..mu.. pairs in the forward direction in ..pi..-nucleus collisions, (5) Crystal Ball group, (6) detector studies, (7) proposed experiment at LEP, and (8) proposal to study electron-positron collisions. (WHK)
Date: August 30, 1982
Creator: Shoemaker, F C
Partner: UNT Libraries Government Documents Department

Future directions of accelerator-based NP and HEP facilities

Description: Progress in particle and nuclear physics has been closely connected to the progress in accelerator technologies - a connection that is highly beneficial to both fields. This paper presents a review of the present and future facilities and accelerator technologies that will push the frontiers of high-energy particle interactions and high intensity secondary particle beams.
Date: July 24, 2011
Creator: Roser, T.
Partner: UNT Libraries Government Documents Department

Exploring Quantum Degenerate Bose-Fermi Mixtures Toward Cooper Pairing of Fermionic Atoms

Description: We have been exploring interaction dynamics in an ultracold, trapped gas of bosonic and fermionic atoms. Investigation of this new class of quantum degenerate gases concentrates on interaction dominated phenomena such as sympathetic cooling, phase separation, excitations, Feshbach resonances, and the effects of quantum degeneracy. In addition to exploring these new phenomena, we seek to understand and ultimately control the interactions in the gas. In particular, effective interactions between the fermionic atoms will be explored in the context of the longer term goal of realizing Cooper pairing of atoms.
Date: April 20, 2011
Creator: Jin, Deborah
Partner: UNT Libraries Government Documents Department

Issues in IIA Uplifting

Description: Moduli stabilization in the type IIA massive string theory so far was achieved only in the AdS vacua. The uplifting to dS vacua has not been performed as yet: neither the analogs of type IIB anti-D3 brane at the tip of the conifold, nor the appropriate D-terms have been identified. The hope was recently expressed that the F-term uplifting may work. We investigate this possibility in the context of a simplified version of the type IIA model developed in hep-th/0505160 and find that the F-term does not uplift the AdS vacua to dS vacua with positive CC. Thus it remains a challenging task to find phenomenologically acceptable vacua in the type IIA string theory.
Date: December 12, 2006
Creator: Kallosh, Renata & Soroush, Masoud
Partner: UNT Libraries Government Documents Department

Asynchronous Event-Driven Particle Algorithms

Description: We present in a unifying way the main components of three examples of asynchronous event-driven algorithms for simulating physical systems of interacting particles. The first example, hard-particle molecular dynamics (MD), is well-known. We also present a recently-developed diffusion kinetic Monte Carlo (DKMC) algorithm, as well as a novel event-driven algorithm for Direct Simulation Monte Carlo (DSMC). Finally, we describe how to combine MD with DSMC in an event-driven framework, and discuss some promises and challenges for event-driven simulation of realistic physical systems.
Date: February 28, 2007
Creator: Donev, A
Partner: UNT Libraries Government Documents Department

Anisotropic diffusion of electrons in liquid xenon with application to improving the sensitivity of direct dark matter searches

Description: Electron diffusion in a liquid xenon time projection chamber has recently been used to infer the z coordinate of a particle interaction, from the width of the electron signal. The goal of this technique is to reduce the background event rate by discriminating edge events from bulk events. Analyses of dark matter search data which employ it would benefit from increased longitudinal electron diffusion. We show that a significant increase is expected if the applied electric field is decreased. This observation is trivial to implement but runs contrary to conventional wisdom and practice. We also extract a first measurement of the longitudinal diffusion coefficient, and confirm the expectation that electron diffusion in liquid xenon is highly anisotropic under typical operating conditions.
Date: February 14, 2011
Creator: Sorensen, P
Partner: UNT Libraries Government Documents Department

Aerosol cluster impact and break-up : model and implementation.

Description: In this report a model for simulating aerosol cluster impact with rigid walls is presented. The model is based on JKR adhesion theory and is implemented as an enhancement to the granular (DEM) package within the LAMMPS code. The theory behind the model is outlined and preliminary results are shown. Modeling the interactions of small particles is relevant to a number of applications (e.g., soils, powders, colloidal suspensions, etc.). Modeling the behavior of aerosol particles during agglomeration and cluster dynamics upon impact with a wall is of particular interest. In this report we describe preliminary efforts to develop and implement physical models for aerosol particle interactions. Future work will consist of deploying these models to simulate aerosol cluster behavior upon impact with a rigid wall for the purpose of developing relationships for impact speed and probability of stick/bounce/break-up as well as to assess the distribution of cluster sizes if break-up occurs. These relationships will be developed consistent with the need for inputs into system-level codes. Section 2 gives background and details on the physical model as well as implementations issues. Section 3 presents some preliminary results which lead to discussion in Section 4 of future plans.
Date: October 1, 2010
Creator: Lechman, Jeremy B.
Partner: UNT Libraries Government Documents Department