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Toward the construction of realistic models from Superstrings
https://ir.soken.ac.jp/records/4071
https://ir.soken.ac.jp/records/40711f4148401c49475ab37c4b159a540c3f
名前 / ファイル  ライセンス  アクション 

要旨・審査要旨 (273.8 kB)

Item type  学位論文 / Thesis or Dissertation(1)  

公開日  20131118  
タイトル  
タイトル  Toward the construction of realistic models from Superstrings  
タイトル  
タイトル  Toward the construction of realistic models from Superstrings  
言語  en  
言語  
言語  eng  
資源タイプ  
資源タイプ識別子  http://purl.org/coar/resource_type/c_46ec  
資源タイプ  thesis  
著者名 
矢田, 雅哉
× 矢田, 雅哉 

フリガナ 
ヤタ, マサヤ
× ヤタ, マサヤ 

著者 
YATA, Masaya
× YATA, Masaya 

学位授与機関  
学位授与機関名  総合研究大学院大学  
学位名  
学位名  博士（理学）  
学位記番号  
内容記述タイプ  Other  
内容記述  総研大甲第1592号  
研究科  
値  高エネルギー加速器科学研究科  
専攻  
値  14 素粒子原子核専攻  
学位授与年月日  
学位授与年月日  20130322  
学位授与年度  
値  2012  
要旨  
内容記述タイプ  Other  
内容記述  The superstring theory has been considered as an important candidate for a fundamental theory. There exist five consistent superstring theory: type I, type IIA, type IIB, SO(32) heterotic and E8×E8 heterotic theories. Heterotic strings automatically include the SO(32) or E8×E8 gauge symmetries, so it can explain the origin of gauge symmetries. Since the E8×E8 gauge group is remarkable from the point of view of the GUTs, E8×E8 heterotic string has been considered to be the most promising theory for describing the physics beyond the Standard Model. On the other hand, type II strings are possible to include gauge symmetries by Dbranes which are higher dimensional objects. The Dbranes have many interesting properties and applications, so various studies have been considered. Although superstring theories possess lots of attractive features, there is no conclusive evidence that the string theories are fundamental theories. The Standard Model does not appear automatically in the superstring theory in the first place. Thus, we must consider the scenario or setup that links the superstring theories at high energy and the Standard Model or the GUTs at low energy. The salient issue is that the superstring theories are consistent only in 10D spacetime. Since the Standard Model (or the GUTs) is in 4D spacetime, we do something about the issue. Usually, the extra 6D space is regarded as an unknown compact manifold and the size of the manifold is assumed to be sufficiently small. The long standing study of superstring theory reveals that the internal 6D space structure relates the framework of the 4D low energy field theories, such as the family structure and gauge groups. Although various approaches have been pursued to construct realistic models, none of the approaches can achieve the success. In heterotic string theory, one of the primary tasks of the string compactification is to find a way to realize a model with less moduli. In this thesis, we introduce a novel, interesting brane setup in heterotic string theory, where we use NS5branes instead of Dbranes. After the brief review of heterotic string theory and orbifold compactifications, we consider the system of two stacks of intersecting NS5brane in E8×E8 heterotic string theory and investigate the localized zeromodes on the branes. Since the generalized spin connection is in SU(3) structure, the system preserves 4D N=1 SUSY and the unbroken gauge symmetry is E6. We perform an explicit computation of the Dirac zeromodes on two types of intersecting fivebrane backgrounds, the domain walltype and vortex type solutions, and confirm that three chiral zeromodes, two are in 27 and one is in ￣27 representations in E6, are localized on the brane in both types of solutions. We also investigate the possibility of realizing warped compactifications in heterotic string theory. It is known that warped compactification needs being with some of negative tension branes. In type II string theories, such an object corresponds to orientifolds. In the other hand, such negative tension objects have not been found in heterotic string theory. We suggest a possible interpretation of the negative tension branes in heterotic theories as a Tdual of the asymptotic form of the AtiyahHitchin manifold. Since the asymptotic form of the AtiyahHitchin manifold agrees with the negative charge TaubNUT metric and TaubNUT solutions can be converted to smeared NS 5brane solutions by Tduality, we can obtain negative tension fivebranes in heterotic string theory. Furthermore, The AtiyahHitchin manifold has a bolt singularity, the negative tension fivebranes behave as orientifold like objects. In order to compactify the extra 4D space, we consider the GibbonsHawking metric for a threedimensional periodic array of multiTaubNUT centers which contain positive NUT charges but also negative NUT charges, where the negative charge TaubNUT is regarded as the asymptotic form of the AtiyahHitchin metric. The array is converted by Tduality to a system of NS5branes with the SU(2) structure, and further considered as a heterotic background by the standard embedding. The one of advantages of the NS5brane construction is that it is a nonzero flux theory. The three form flux is beneficial to moduli stabilization, even if it cannot stabilize completely in heterotic string theory. It is also noteworthy that the setup is the new way that achieves the warped compactification in heterotic string theory. 

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