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Heterotic String Compactification with a View Towards Cosmology
Heterotic String Compactification with a View Towards Cosmology by Jørgen Olsen Lye Thesis for the degree Master of Science (Master i fysikk) Department of Physics Faculty of Mathematics and Natural Sciences University of Oslo May 2014 Abstract The goal is to look at what constraints there are for the internal manifold in phe- nomenologically viable Heterotic string compactification. Basic string theory, cosmology, and string compactification is sketched. I go through the require- ments imposed on the internal manifold in Heterotic string compactification when assuming vanishing 3-form flux, no warping, and maximally symmetric 4-dimensional spacetime with unbroken N = 1 supersymmetry. I review the current state of affairs in Heterotic moduli stabilisation and discuss merging cosmology and particle physics in this setup. In particular I ask what additional requirements this leads to for the internal manifold. I conclude that realistic manifolds on which to compactify in this setup are severely constrained. An extensive mathematics appendix is provided in an attempt to make the thesis more self-contained. Acknowledgements I would like to start by thanking my supervier Øyvind Grøn for condoning my hubris and for giving me free rein to delve into string theory as I saw fit. It has lead to a period of intense study and immense pleasure. Next up is my brother Kjetil, who has always been a good friend and who has been constantly looking out for me. It is a source of comfort knowing that I can always turn to him for help. Mentioning friends in such an acknowledgement is nearly mandatory. At least they try to give me that impression. -
Sacred Rhetorical Invention in the String Theory Movement
University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Communication Studies Theses, Dissertations, and Student Research Communication Studies, Department of Spring 4-12-2011 Secular Salvation: Sacred Rhetorical Invention in the String Theory Movement Brent Yergensen University of Nebraska-Lincoln, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/commstuddiss Part of the Speech and Rhetorical Studies Commons Yergensen, Brent, "Secular Salvation: Sacred Rhetorical Invention in the String Theory Movement" (2011). Communication Studies Theses, Dissertations, and Student Research. 6. https://digitalcommons.unl.edu/commstuddiss/6 This Article is brought to you for free and open access by the Communication Studies, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Communication Studies Theses, Dissertations, and Student Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. SECULAR SALVATION: SACRED RHETORICAL INVENTION IN THE STRING THEORY MOVEMENT by Brent Yergensen A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy Major: Communication Studies Under the Supervision of Dr. Ronald Lee Lincoln, Nebraska April, 2011 ii SECULAR SALVATION: SACRED RHETORICAL INVENTION IN THE STRING THEORY MOVEMENT Brent Yergensen, Ph.D. University of Nebraska, 2011 Advisor: Ronald Lee String theory is argued by its proponents to be the Theory of Everything. It achieves this status in physics because it provides unification for contradictory laws of physics, namely quantum mechanics and general relativity. While based on advanced theoretical mathematics, its public discourse is growing in prevalence and its rhetorical power is leading to a scientific revolution, even among the public. -
Flux, Gaugino Condensation and Anti-Branes in Heterotic M-Theory
Flux, Gaugino Condensation and Anti-Branes in Heterotic M-theory James Gray1, Andr´eLukas2 and Burt Ovrut3 1Institut d’Astrophysique de Paris and APC, Universit´ede Paris 7, 98 bis, Bd. Arago 75014, Paris, France 2Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, UK 3Department of Physics, University of Pennsylvania, Philadelphia, PA 19104–6395, USA Abstract We present the potential energy due to flux and gaugino condensation in heterotic M- theory compactifications with anti-branes in the vacuum. For reasons which we explain in detail, the contributions to the potential due to flux are not modified from those in supersymmetric contexts. The discussion of gaugino condensation is, however, changed by the presence of anti-branes. We show how a careful microscopic analysis of the system allows us to use standard results in supersymmetric gauge theory in describing such effects - despite arXiv:0709.2914v1 [hep-th] 18 Sep 2007 the explicit supersymmetry breaking which is present. Not surprisingly, the significant effect of anti-branes on the threshold corrections to the gauge kinetic functions greatly alters the potential energy terms arising from gaugino condensation. 1email: [email protected] 2email: [email protected] 3email: [email protected] 1 Introduction In [1], the perturbative four-dimensional effective action of heterotic M-theory compactified on vacua containing both branes and anti-branes in the bulk space was derived. That paper concentrated specif- ically on those aspects of the perturbative low energy theory which are induced by the inclusion of anti-branes. Hence, for clarity of presentation, the effect of background G-flux on the effective theory was not discussed. -
Time in Cosmology
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Philsci-Archive Time in Cosmology Craig Callender∗ C. D. McCoyy 21 August 2017 Readers familiar with the workhorse of cosmology, the hot big bang model, may think that cosmology raises little of interest about time. As cosmological models are just relativistic spacetimes, time is under- stood just as it is in relativity theory, and all cosmology adds is a few bells and whistles such as inflation and the big bang and no more. The aim of this chapter is to show that this opinion is not completely right...and may well be dead wrong. In our survey, we show how the hot big bang model invites deep questions about the nature of time, how inflationary cosmology has led to interesting new perspectives on time, and how cosmological speculation continues to entertain dramatically different models of time altogether. Together these issues indicate that the philosopher interested in the nature of time would do well to know a little about modern cosmology. Different claims about time have long been at the heart of cosmology. Ancient creation myths disagree over whether time is finite or infinite, linear or circular. This speculation led to Kant complaining in his famous antinomies that metaphysical reasoning about the nature of time leads to a “euthanasia of reason”. But neither Kant’s worry nor cosmology becoming a modern science succeeded in ending the speculation. Einstein’s first model of the universe portrays a temporally infinite universe, where space is edgeless and its material contents unchanging. -
Arxiv:1705.06729V4 [Hep-Th] 25 Jul 2017
Supergravitational Conformal Galileons Rehan Deen and Burt Ovrut Department of Physics and Astronomy University of Pennsylvania Philadelphia, PA 19104{6396 Abstract The worldvolume actions of 3+1 dimensional bosonic branes embedded in a five-dimensional bulk space can lead to important effective field theories, such as the DBI conformal Galileons, and may, when the Null Energy Condition is violated, play an essential role in cosmological theories of the early universe. These include Galileon Genesis and \bouncing" cosmology, where a pre-Big Bang contracting phase bounces smoothly to the presently observed expanding universe. Perhaps the most natural arena for such branes to arise is within the context of superstring and M-theory vacua. Here, not only are branes required for the consistency of the theory, but, in many cases, the exact spectrum of particle physics occurs at low energy. However, such theories have the additional constraint that they must be N = 1 supersymmetric. This motivates us to compute the worldvolume actions of N = 1 supersymmetric three-branes, first in flat superspace and then to generalize them to N = 1 supergravitation. In this paper, for simplicity, we begin the process, not within the context of a superstring vacuum but, rather, for the conformal Galileons arising on a co-dimension one brane embedded in a maximally symmetric AdS5 bulk space. We proceed to N = 1 supersymmetrize the associated worldvolume theory and then generalize the results to N = 1 supergravity, opening the door to possible new cosmological scenarios. -
Editorial Computational Algebraic Geometry in String and Gauge Theory
Hindawi Publishing Corporation Advances in High Energy Physics Volume 2012, Article ID 431898, 4 pages doi:10.1155/2012/431898 Editorial Computational Algebraic Geometry in String and Gauge Theory Yang-Hui He,1, 2, 3 Philip Candelas,4 Amihay Hanany,5 Andre Lukas,6 and Burt Ovrut7 1 Department of Mathematics, City University London, London EC1V 0HB, UK 2 School of Physics, Nan Kai University, TianJin 300071, China 3 Merton College, University of Oxford, Oxford OX1 4JD, UK 4 Mathematical Institute, University of Oxford, 24-29 St Giles’, Oxford OX1 3LB, UK 5 Department of Physics, Imperial College, London SW7 2AZ, UK 6 Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, UK 7 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 191046395, USA Correspondence should be addressed to Yang-Hui He, [email protected] Received 23 November 2011; Accepted 23 November 2011 Copyright q 2012 Yang-Hui He et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The last few years have witnessed a rapid development in algebraic geometry, computer algebra, and string and field theory, as well as fruitful cross-fertilization amongst them. The dialogue between geometry and gauge theory is, of course, an old and rich one, leading to tools crucial to both. The introduction of algorithmic and computational algebraic geometry, however, is relatively new and is tremendously facilitated by the rapid progress in hardware, software as well as theory. -
The Ekpyrotic Universe: Colliding Branes and the Origin of the Hot Big
View metadata, citation and similar papers at core.ac.uk brought to you by CORE The Ekpyrotic Universe: Colliding Branes and the Origin ofprovided the by CERN Document Server Hot Big Bang Justin Khoury1,BurtA.Ovrut2,PaulJ.Steinhardt1 and Neil Turok 3 1 Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544, USA 2 Department of Physics, University of Pennsylvania, Philadelphia, PA 19104-6396, USA 3 DAMTP, CMS, Wilberforce Road, Cambridge, CB3 0WA, UK Abstract We propose a cosmological scenario in which the hot big bang universe is produced by the collision of a brane in the bulk space with a bounding orb- ifold plane, beginning from an otherwise cold, vacuous, static universe. The model addresses the cosmological horizon, flatness and monopole problems and generates a nearly scale-invariant spectrum of density perturbations with- out invoking superluminal expansion (inflation). The scenario relies, instead, on physical phenomena that arise naturally in theories based on extra di- mensions and branes. As an example, we present our scenario predominantly within the context of heterotic M-theory. A prediction that distinguishes this scenario from standard inflationary cosmology is a strongly blue gravitational wave spectrum, which has consequences for microwave background polariza- tion experiments and gravitational wave detectors. Typeset using REVTEX 1 I. INTRODUCTION The Big Bang model provides an accurate account of the evolution of our universe from the time of nucleosynthesis until the present, but does not address the key -
Astro2020 Science White Paper Probing the Origin of Our Universe Through Cosmic Microwave Background Constraints on Gravitational Waves
Astro2020 Science White Paper Probing the origin of our Universe through cosmic microwave background constraints on gravitational waves Thematic Areas: Planetary Systems Star and Planet Formation Formation and Evolution of Compact Objects X Cosmology and Fundamental Physics Stars and Stellar Evolution Resolved Stellar Populations and their Environments Galaxy Evolution Multi-Messenger Astronomy and Astrophysics Principal Author: Name: Sarah Shandera Institution: The Pennsylvania State University Email: [email protected] Phone: (814)863-9595 Co-authors: Peter Adshead (U. Illinois), Mustafa Amin (Rice University), Emanuela Dimastrogiovanni (University of New South Wales), Cora Dvorkin (Harvard University), Richard Easther (University of Auckland), Matteo Fasiello (Institute of Cosmology and Gravitation, University of Portsmouth), Raphael Flauger (University of California, San Diego), John T. Giblin, Jr (Kenyon College), Shaul Hanany (University of Minnesota), Lloyd Knox (Univerisity of California, Davis), Eugene Lim (King’s College London), Liam McAllister (Cornell University), Joel Meyers (Southern Methodist University), Marco Peloso (University of Padova, and INFN, Sezione di Padova), Graca Rocha (Jet Propulsion Laboratory), Maresuke Shiraishi (National Institute of Technology, Kagawa College), Lorenzo Sorbo (University of Massachusetts, Amherst), Scott Watson (Syracuse University) Endorsers: Zeeshan Ahmed1, David Alonso2, Robert Armstrong3, Mario Ballardini4, Darcy Barron5, Nicholas Battaglia6, Daniel Baumann7;8, Charles Bennett9, -
Nonsingular Ekpyrotic Cosmology with a Nearly Scale-Invariant Spectrum of Cosmological Perturbations and Gravitational Waves
PHYSICAL REVIEW D 101, 063522 (2020) Nonsingular ekpyrotic cosmology with a nearly scale-invariant spectrum of cosmological perturbations and gravitational waves † Robert Brandenberger * and Ziwei Wang Department of Physics, McGill University, Montr´eal, Quebec City, H3A 2T8, Canada (Received 6 February 2020; accepted 3 March 2020; published 20 March 2020) We propose a mechanism borrowed from string theory which yields a nonsingular transition from a phase of ekpyrotic contraction to the expanding phase of standard big bang cosmology. The same mechanism converts the initial vacuum spectrum of cosmological fluctuations before the bounce into a scale-invariant one, and also changes the spectrum of gravitational waves into an almost scale-invariant one. The scalar and tensor tilts are predicted to be the same, in contrast to the predictions from the “string gas cosmology” scenario. The amplitude of the gravitational wave spectrum depends on the ratio of the string scale to the Planck scale and may be in reach of upcoming experiments. DOI: 10.1103/PhysRevD.101.063522 I. INTRODUCTION scalar field φ to serve as an inflaton, its potential energy VðφÞ has to be very flat in order that the potential energy The inflationary universe scenario [1] has become the dominates over the kinetic energy.1 However, general standard paradigm of early universe cosmology. It is based arguments from string theory lead to the swampland on the assumption that there was a period of almost constraint [5] (see [6] for reviews) exponential expansion during a time period -
Theoretical Studies of Cosmic Acceleration
University of Pennsylvania ScholarlyCommons Publicly Accessible Penn Dissertations 2016 Theoretical Studies of Cosmic Acceleration James Stokes University of Pennsylvania, [email protected] Follow this and additional works at: https://repository.upenn.edu/edissertations Part of the Physics Commons Recommended Citation Stokes, James, "Theoretical Studies of Cosmic Acceleration" (2016). Publicly Accessible Penn Dissertations. 2040. https://repository.upenn.edu/edissertations/2040 This paper is posted at ScholarlyCommons. https://repository.upenn.edu/edissertations/2040 For more information, please contact [email protected]. Theoretical Studies of Cosmic Acceleration Abstract In this thesis we describe theoretical approaches to the problem of cosmic acceleration in the early and late universe. The first approach we consider relies upon the modification of Einstein gravity by the inclusion of mass terms as well as couplings to higher-derivative scalar fields possessing generalized internal shift symmetries - the Galileons. The second half of the thesis is concerned with the quantum- mechanical consistency of a theory of the early universe known as the pseudo-conformal mechanism which, in contrast to inflation, eliesr not on the effects of gravity but on conformal field theory (CFT) dynamics. It is possible to couple Dirac-Born-Infeld (DBI) scalars possessing generalized Galilean internal shift symmetries (Galileons) to nonlinear massive gravity in four dimensions, in such a manner that the interactions maintain the Galilean symmetry. Such a construction is of interest because it is not possible to couple such fields ot massless General Relativity in the same way. Using tetrad techniques we show that this massive gravity-Galileon theory possesses a primary constraint necessary to ensure propagation with the correct number of degrees of freedom. -
Exploring Bouncing Cosmologies with Cosmological Surveys
Exploring Bouncing Cosmologies with Cosmological Surveys Yi-Fu Cai1, ∗ 1Department of Physics, McGill University, Montr´eal,QC, H3A 2T8, Canada In light of the recent observational data coming from the sky we have two significant directions in the field of theoretical cosmology recently. First, we are now able to make use of present observations, such as the Planck and BICEP2 data, to examine theoretical predictions from the standard inflationary ΛCDM which were made decades of years ago. Second, we can search for new cosmological signatures as a way to explore physics beyond the standard cosmic paradigm. In particular, a subset of early universe models admit a nonsingular bouncing solution that attempts to address the issue of the big bang singularity. These models have achieved a series of considerable developments in recent years, in particular in their perturbative frameworks, which made brand-new predictions of cosmological signatures that could be visible in current and forthcoming observations. In this article we present two representative paradigms of very early universe physics. The first is the so-called new matter (or matter-ekpyrotic) bounce scenario in which the universe starts with a matter-dominated contraction phase and transitions into an ekpyrotic phase. In the setting of this paradigm, we propose some possible mechanisms of generating a red tilt for primordial curvature perturbations and confront its general predictions with recent cosmological observations. The second is the matter-bounce inflation scenario which can be viewed as an extension of inflationary cosmology with a matter contraction before inflation. We present a class of possible model constructions and review its implications on the current CMB experiments. -
Balanced Metrics and Phenomenological Aspects of Heterotic Compactifications
University of Pennsylvania ScholarlyCommons Publicly Accessible Penn Dissertations Fall 2010 Balanced Metrics and Phenomenological Aspects of Heterotic Compactifications Tamaz Brelidze University of Pennsylvania, [email protected] Follow this and additional works at: https://repository.upenn.edu/edissertations Part of the Elementary Particles and Fields and String Theory Commons Recommended Citation Brelidze, Tamaz, "Balanced Metrics and Phenomenological Aspects of Heterotic Compactifications" (2010). Publicly Accessible Penn Dissertations. 254. https://repository.upenn.edu/edissertations/254 This paper is posted at ScholarlyCommons. https://repository.upenn.edu/edissertations/254 For more information, please contact [email protected]. Balanced Metrics and Phenomenological Aspects of Heterotic Compactifications Abstract ABSTRACT BALANCED METRICS AND PHENOMENOLOGICAL ASPECTS OF HETEROTIC STRING COMPACTIFICATIONS Tamaz Brelidze Burt Ovrut, Advisor This thesis mainly focuses on numerical methods for studying Calabi-Yau manifolds. Such methods are instrumental in linking models inspired by the mi- croscopic physics of string theory and the observable four dimensional world. In particular, it is desirable to compute Yukawa and gauge couplings. However, only for a relatively small class of geometries can those be computed exactly using the rather involved tools of algebraic geometry and topological string theory. Numerical methods provide one of the alternatives to go beyond these limitations. In this work we describe numerical