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in subjects: "Stanford Linear Accelerator Center Theory-Hep,Hepth"

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Investigating Inflation in Type IIA

We prove that inflation is forbidden in the most well understood class of semi-realistic type IIA string compactifications: Calabi-Yau compactifications with only standard NS-NS 3-form flux, R-R fluxes, D6-branes and O6-planes at large volume and small string coupling. With these ingredients, the first slow-roll parameter satisfies {epsilon} {ge} 27/13 whenever V > 0, ruling out both inflation (including brane/anti-brane inflation) and de Sitter vacua in this limit. Our proof is based on the… more

Date: December 14, 2007

Creator: Hertzberg, Mark P.; /MIT; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC; Taylor, Washington; Tegmark, Max et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

What is Science?

Helen Quinn is a theoretical particle physicist at SLAC. Throughout her career, she has been passionately involved in science education and public understanding of science. In talking about science, whether to the public or to students, we scientists often assume that they share with us a common idea of science. In my experience that is often not the case. To oversimplify, scientists think of science both as a process for discovering properties of nature, and as the resulting body of knowledge,… more

Date: August 3, 2009

Creator: Quinn, H

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Stringy Instantons and Quiver Gauge Theories

We explore contributions to the 4D effective superpotential which arise from Euclidean D3 branes (''instantons'') that intersect space-filling D-branes. These effects can perturb the effective field theory on the space-filling branes by nontrivial operators composed of charged matter fields, changing the vacuum structure in a qualitative way in some examples. Our considerations are exemplified throughout by a careful study of a fractional brane configuration on a del Pezzo surface.

Date: October 24, 2006

Creator: Florea, Bogdan; Kachru, Shamit; McGreevy, John & Saulina, Natalia

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A High Temperature Phase Transition in Weakly Coupled Large N Gauge Theories on a Three-sphere

We argue that weakly coupled 3+1 dimensional large N SU(N) gauge theories, with 't Hooft coupling {gamma}, compactified on a three-sphere of radius R, exhibit a novel second order phase transition at a temperature T{sub c} = C{radical}{gamma} R. The known constant C depends on the details of the gauge theory. The phase transition is characterized by a change in the eigenvalue distributions of the fields. Above the transition, the only eigenvalues which condense are those of the lowest Kaluza-Kl… more

Date: June 22, 2007

Creator: Aharony, Ofer & Hartnoll, Sean A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

String Cosmology: A Review

We give an overview of the status of string cosmology. We explain the motivation for the subject, outline the main problems, and assess some of the proposed solutions. Our focus is on those aspects of cosmology that benefit from the structure of an ultraviolet-complete theory.

Date: October 22, 2007

Creator: McAllister, Liam P. & Silverstein, Eva

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Axions in String Theory

In the context of string theory, axions appear to provide the most plausible solution of the strong CP problem. However, as has been known for a long time, in many string-based models, the axion coupling parameter Fa is several orders of magnitude higher than the standard cosmological bounds. We re-examine this problem in a variety of models, showing that Fa is close to the GUT scale or above in many models that have GUT-like phenomenology, as well as some that do not. On the other hand, in som… more

Date: June 9, 2006

Creator: Svrcek, Peter; /Stanford U., Phys. Dept. /SLAC; Witten, Edward & /Princeton, Inst. Advanced Study

Item Type: Report

Partner: UNT Libraries Government Documents Department