Phenomenological Analysis of Heterotic Strings: Non-abelian Constructions and Landscape Studies

Persistent Link:
http://hdl.handle.net/10150/195116
Title:
Phenomenological Analysis of Heterotic Strings: Non-abelian Constructions and Landscape Studies
Author:
Wasnik, Vaibhav Hemant
Issue Date:
2009
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
String theory offers the unique promise of unifying all the known forces in nature. However, the internal consistency of the theory requires that spacetime have more than four dimensions. As a result, the extra dimensions must be compactified in some manner and how this compactification takes place is critical for determining the low-energy physical predictions of the theory. In this thesis we examine two distinct consequences of this fact.First, almost all of the prior research in string model-building has examined the consequences of compactifying on so-called ``abelian'' orbifolds.However, the most general class of compactifications, namely those onnon-abelian orbifolds, remains almost completely unexplored. This thesis focuses on the low-energy phenomenological consequences of compactifying strings on non-abelian orbifolds. One of the main interests in pursuing these theories is that they can, in principle, naturally give rise tolow-energy models which simultaneously have N=1 super symmetry along with scalar particles transforming in the adjoint of the gauge group. These features,which are exceedingly difficult to achieve through abelian orbifolds,are exciting because they are the key ingredients in understanding how grand unification can emerge from string theory.Second, the need to compactify gives rise to a huge ``landscape'' of possible resulting low-energy phenomenologies. One of the goals of the landscape program in string theory is then to extract information about the space of string vacua in the form of statistical correlations between phenomenological features that are otherwise uncorrelated in field theory. Such correlations would thus represent features of string theory that hold independently of a vacuum-selection principle. In this thesis, we study statistical correlations between two features which are likely to be central to any potential description of nature at high-energy scales: gauge symmetries and spacetime supersymmetry. We analyze correlations between these two kinds of symmetry within the context of perturbative heterotic string vacua, and find a number of striking features. We find, for example, that the degree of spacetime supersymmetry is strongly correlated with the probabilities of realizing certain gauge groups, with unbroken supersymmetry at the string scale tending to favor gauge-group factors with larger rank. We also find that nearly half of the heterotic landscape is nonsupersymmetric and yet tachyon-free at tree level; indeed, less than a quarter of the tree-level heterotic landscape exhibits any supersymmetry at all at the string scale.
Type:
text; Electronic Dissertation
Keywords:
Physics
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Physics; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Dienes, Keith R.
Committee Chair:
Dienes, Keith R.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titlePhenomenological Analysis of Heterotic Strings: Non-abelian Constructions and Landscape Studiesen_US
dc.creatorWasnik, Vaibhav Hemanten_US
dc.contributor.authorWasnik, Vaibhav Hemanten_US
dc.date.issued2009en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractString theory offers the unique promise of unifying all the known forces in nature. However, the internal consistency of the theory requires that spacetime have more than four dimensions. As a result, the extra dimensions must be compactified in some manner and how this compactification takes place is critical for determining the low-energy physical predictions of the theory. In this thesis we examine two distinct consequences of this fact.First, almost all of the prior research in string model-building has examined the consequences of compactifying on so-called ``abelian'' orbifolds.However, the most general class of compactifications, namely those onnon-abelian orbifolds, remains almost completely unexplored. This thesis focuses on the low-energy phenomenological consequences of compactifying strings on non-abelian orbifolds. One of the main interests in pursuing these theories is that they can, in principle, naturally give rise tolow-energy models which simultaneously have N=1 super symmetry along with scalar particles transforming in the adjoint of the gauge group. These features,which are exceedingly difficult to achieve through abelian orbifolds,are exciting because they are the key ingredients in understanding how grand unification can emerge from string theory.Second, the need to compactify gives rise to a huge ``landscape'' of possible resulting low-energy phenomenologies. One of the goals of the landscape program in string theory is then to extract information about the space of string vacua in the form of statistical correlations between phenomenological features that are otherwise uncorrelated in field theory. Such correlations would thus represent features of string theory that hold independently of a vacuum-selection principle. In this thesis, we study statistical correlations between two features which are likely to be central to any potential description of nature at high-energy scales: gauge symmetries and spacetime supersymmetry. We analyze correlations between these two kinds of symmetry within the context of perturbative heterotic string vacua, and find a number of striking features. We find, for example, that the degree of spacetime supersymmetry is strongly correlated with the probabilities of realizing certain gauge groups, with unbroken supersymmetry at the string scale tending to favor gauge-group factors with larger rank. We also find that nearly half of the heterotic landscape is nonsupersymmetric and yet tachyon-free at tree level; indeed, less than a quarter of the tree-level heterotic landscape exhibits any supersymmetry at all at the string scale.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectPhysicsen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorDienes, Keith R.en_US
dc.contributor.chairDienes, Keith R.en_US
dc.contributor.committeememberSu, Shufangen_US
dc.contributor.committeemembervan Kolck, Ubirajaraen_US
dc.contributor.committeememberTouissant, Dougen_US
dc.identifier.proquest10679en_US
dc.identifier.oclc659753437en_US
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