| 研究課題/領域番号 |
26400242
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| 研究機関 | 東京大学 |
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研究代表者 |
HELLERMAN Simeon 東京大学, カブリ数物連携宇宙研究機構, 准教授 (70534949)
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| 研究期間 (年度) |
2014-04-01 – 2017-03-31
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| キーワード | String theory / Non-supersymmetric |
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| 研究実績の概要 |
String theory is complicated. It is very important that we, as a scientific community, understand it clearly.
First of all, my collaborators (John Kehayias and Tsutomu Yanagida) and I, have been able to work out a totally new phenomenological scenario for beyond-Standard-Model physics. Our sceneario is based on the fundamental non-linear realization of a GUT-like group, of which only the Stanfard Model gauge group is realised as an unbroken subgroup.
The phenomenological consequences of this scenario are striking. We still have U(1) hypercharge quantization -- for which there has often been thought to be no theoretical reason without embedding in a grand unified gauge group. Beyond that, the consequences depend on the exact nonlinearly realized simple group in which the Standard Model gauge group is embedded. In certain scenarios, there are new dark matter particles. In other scenarios, the Higgs itself may be a pseudo-Nambu-Goldstone boson of the nonlinearly realized group. We have shown that a great many such scenarios are phenomenologically viable. The string-theoretic significance of these scenarios is that they may provide an effective low-energy description in four dimensions of scenarii in which the SM gauge group unifies in higher dimensions but not in four. (Heterotic string theory on a Calami-Yau manifold is one such type of scenario.) The moduli spaces of such models are generically 4D sigma models on cosets, in the low-energy description below the Kaluza-Klein scale. Our models are the first candidate low-energy effective theories of such compactifications.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
The purpose of this research is-if I may quote my own proposal-"to develop tools to define quantum gravity models and allow calculations in the landscape of generic environments-for highly generic realizations of supersymmetric low-energy physics, or even in the absence of supersymmetry altogether."I believe I have achieved those goals during 2014 even better than according to my original plan.
First of all, my research on effective QCD string theory that was completed in 2014 (one publication with Ian Swanson, and another publication with I. Swanson, Shunsuke Maeda, and Jonathan Maltz), certainly achieved the goal of " begin[ning] to apply the study of generic string theory to phenomenologically relevant situations, such as spacetimes describing confining gauge theory through holographic duality".In fact, those publications achieved FAR MORE than that:They achieved the first controlled, quantitative application of gauge-string duality to describe the spectrum of gauge singlets in fully nonsupersymmetric gauge theory (planar QCD with bosonic quarks) in a particular limit:The limit of large spin J.In addition to recovering the usual linear Regge spectrum of mass-squared versus angular momentum as a leading approximation, we were able to calculate a sub-leading correction that was universal, independent of the details of the worldsheet Lagrangian of the string.
In addition, our work with Yanagida and Kehayias, continued in 2014, certainly achieved the goal of "describing cosmological behavior, and the physics of electroweak symmetry breaking and beyond-Standard-Model dynamics."
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| 今後の研究の推進方策 |
My plan for research in the future, in particular in the coming fiscal year and beyond, is as follows.
(1) Formulate a precise characterisation of the holographic properties of generic string backgrounds of the type under study in this project. [Cosmological, confining, ..., etc.]
(2) Translate those holographic properties into precise properties of the non-gravitational holographic theory living on the conformal boundary at infinity.
(3) Use bootstrap methods to work out the consequences of those properties for the spectrum of operators and the correlation functions of the CFT.
We have already made preliminary steps toward (3). In work in progress with several collaborators (Masataka Watanabe, Susanne Reffert, and Domenico Orlando), soon to be submitted as a preprint, we have explored the idea of simplifying the bootstrap constraints by constructing Lagrangians that can be used to calculate amplitudes even in strongly coupled CFT. We have worked out specific cases in three dimensions of strongly coupled CFT previously inaccessible to analytical tools: The cases of the critical O(2) model and the supersymmetric fixed point with a single chiral superfield and cubic superpotential. I plan to finish this paper and to do various follow-up work in the same direction, on the simplification and systematization of the bootstrap constraints. Further, I plan to study (1) and (2), using the increasingly developed modern tools of the quantum information theory of holographic gravity.
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| 次年度使用額が生じた理由 |
As to the carry-over of some portion of the funds from FY2014, the reason was principally this: We made an unexpectedly large amount of progress with simple analytic methods, without the need for a faster computer, in FY2014. So we didn't buy one. It is only now that the need for a faster machine has become more acute, and we need to buy a computer in FY2015.
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| 次年度使用額の使用計画 |
To bring collaborators for an extended period. In particular, my collaborators D. Orlando and S. Reffert have been involved over a long period of time in developing the ideas of simplifying the bootstrap in strongly coupled CFT by lagrangianizing it.
To travel to other institutions:First, to propagate the ideas developed in this project by presenting it at seminars, workshops, and conferences. Second, for me to learn as much as possible from researchers at other institutions about holographic gravity and its relation to strongly coupled CFT, and also the development of modern approaches to strongly coupled CFT via the conformal bootstrap.
To buy a computer. Calculations in this subject can get long and involved, so having a fast machine on which to run Mathematica, is of importance.
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