2003 Fiscal Year Final Research Report Summary
Supersymmetric Grand Unified Theory based on Brain World Picture
Project/Area Number 
13640279

Research Category 
GrantinAid for Scientific Research (C)

Allocation Type  Singleyear Grants 
Section  一般 
Research Field 
素粒子・核・宇宙線

Research Institution  Kyoto University 
Principal Investigator 
KUGO Taichi Kyoto University, Yukawa Institute for Theoretical Physics, Professor > 京都大学, 基礎物理学研究所, 教授 (00115833)

Project Period (FY) 
2001 – 2003

Keywords  brave world scenario / suuerconformal tensor calculus / orbifold / tripletdoublet splitting / neutrino oscillation / E6 grand unified theory / mass matrix / anomalous U(1) charge 
Research Abstract 
The research results of our project for three academic years in 2001 2003 are as follows: 1. Brane world scenario: In order to study the brave world scenario that our world is a threebrave in a higher dimensional space, we consider the simplest case of five dimensional spacetime for which the extra onedimension is compactified to an orbifold S^1/Z_2. We have given the superconformal tensor calculus for such orbifold case and, in particular, clarified the general rule for writing down the superconformal invariant coupling of the matters on the brave to the bulk supergravity and super YangMills multiplets. We also found for the first time that there exist two types of 5D tensor multiplets, gauge and nongauge ones, in another paper and gave the superconformal tensor calculus for them. We also gave a completely offshell formulation for "Supersymmetry in Singular Spaces" by Bergshoeff KalloshVan Proeyen. With this we have shown that the supersymmetry automatically guarantees the speci
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al relation between the boundary brave tensions and the bulk cosmological term required in the RandallSundrum Scenario. In the AltendorferBaggerNemeschansky approach, on the other hand, we have shown that such a relation does not follow from the supersymmetry but remains to be a finetuning. 2. Higgs field and quark/lepton mixing in supersymmetric E6 grand unified theory: We examined the pseudoNambuGoldstone boson idea for the Higgs doublet in supersymmetric E6 GUT framework in order to solve the tripletdoublet splitting problem. We found that there necessarily appear extra light pseudoNambuGoldstone bosons other than the desired Higgs doublets; those extra PsNG bosons must uniquely be 10 + 10* representation of SU(5) in order for them not to disturb the gauge coupling unification. Their existence is shown to be barely consistent with the present experimental bound for proton decay. Under the assumptions that 1) the quark/lepton mass matrices take FroggattNielsen's factorized power form with the powers given by anomalous U(1) charges, and 2) the U(1) charges respect the SU(5) GUT structure, we showed that the quark mass data necessarily implies the large 23 mixing for neutrinos. If the masssquared difference ratio data of solar and atmospheric neutrinos is used as an input, then, it implies that the 12 mixing must also be large (namely, bilarge mixing). We also add an argument that E6 GUT is favored. Less

Research Products
(12 results)