#### Heterotic ns5

Heterotic string compactifications can be conveniently described in the language of 2,0 gauged linear sigma models GLSMs. We show that field dependent non-gauge invariant FI-terms lead to a Green-Schwarz-like mechanism on the worldsheet which can be used to cancel worldsheet anomalies. However, given that these FI-terms are constrained by quantization conditions due to worldsheet gauge instantons, the anomaly conditions turn out to be still rather constraining. This is a preview of subscription content, log in to check access.

Rent this article via DeepDyve. Gross, J. Harvey, E. Martinec and R. Rohm, Heterotic String Theory. The Free Heterotic StringNucl.

The Interacting Heterotic StringNucl. Dixon, J. Harvey, C. Vafa and E. Witten, Strings on OrbifoldsNucl.

Witten, Strings on Orbifolds. Mas, H. Nilles and F. Lebedev et al. Hamaguchi, O.We analyze heterotic line bundle models on elliptically fibered Calabi-Yau three-folds over weak Fano bases. In order to facilitate Wilson line breaking to the standard model group, we focus on elliptically fibered three-folds with a second section and a freely-acting involution.

Specifically, we consider toric weak Fano surfaces as base manifolds and identify six such manifolds with the required properties.

The requisite mathematical tools for the construction of line bundle models on these spaces, including the calculation of line bundle cohomology, are developed. A common and surprising feature of these models is the presence of a large number of vector-like states.

More details from the publisher. More details. Details from ORA. Details from ArXiV. We study F-theory duals of heterotic line bundle models on elliptically fibered Calabi-Yau threefolds.

These models necessarily contain NS5-branes which are geometrized in the dual F-theory compactifications. We initiate a systematic study of the correspondence between various configurations of NS5-branes and the dual geometries in F-theory and perform several checks of the duality. Furthermore, we discuss the singular transitions between different configurations of NS5-branes. In this subspace, the spectrum of the Hessian matrix contains no tachyons, but there are also no critical points.

We contrast these results with the expectations from the much-used continuous flux approximation, and comment on the applicability of Random Matrix Theory to the statistical modelling of the string theory landscape. Enter the terms you wish to search for. Department of Physics.

Log in.Friday, 20 February Heterotic Supergravity. The story in the heterotic theory is more interesting and inspiring. The type I Yang-Mills supergravity theory in ten-dimensions is the low energy effective limit of the type I superstring theory and the heterotic string theory. String theories require higher order corrections to their corresponding low energy supergravity effective actions. The leading type II string corrections are of order, and include terms the fourth power of the Riemann tensorboth at tree level and one loop.

These string corrections to supergravity theories should obviously be supersymmetric. Unfortunately there is still no known way to compute these corrections in a manifestly supersymmetric way, although important progresses have been achieved. In this situation, one might try to study the constraints that ten-dimensional supersymmetry imposes on higher-order contributions to the effective action.

One difficulty here is that, with the exception of the supergravity sector of the heterotic string, it is not known how to construct any superspace actions due to the absence of any known sets of auxiliary fields.

Even in the heterotic case, the auxiliary fields are rather complicated and it is not clear how to construct higher order actions which correspond to superstring corrections, although the invariant was discussed from this point of view. Although supergravity theory was not shown to be a finite perturbation theory to all orders, their effective actions are still crucial for many applications, especially because of the remarkable fact that they turned out to describe the low-energy effective behavior of superstring theories.

Several different methods can be use to formulate supergravity theories and their derivative corrections. This mechanism of calculating the low-energy effective action might be applied as well for supersymmetric string, i.

Indeed, it has been shown that the low-energy approximation of superstring is the dimensional supergravity, locally supersymmetric quantum field theory. We will introduce the supergravity action as the low-energy effective action of superstring theories. We shall also outline various approaches that have been used to construct such an action and the corresponding higher derivative corrections.

Field redefinitions and equivalent effective actions will be studied for the heterotic string to the order, having the Chern-Simons terms included.

We have devoted this article to introduce a supergravity action as the low-energy effective action of a superstring theory, outlining the most powerful methods that have been pursued for constructing such an action and the contributions to them.

We will begin with the ten-dimensional spacetime Lagrangian of the anomaly-free heterotic supergravity coupled to Yang-Mills fields. Extension to a sector with nonabelian Yang-Mills fields requires inclusion of a crucial Kalb-Ramond term in the Lagrangian, necessitated by the mixed gauge-gravity anomaly cancellation conditions. Another feature of interest in this Lagrangian is the possibility of a field-dualization: the Lagrangian can be expressed interchangeably in terms of either a two-form, or a six-form, supergravity potential.In string theorya heterotic string is a closed string or loop which is a hybrid 'heterotic' of a superstring and a bosonic string.

Heterotic string theory was first developed in by David GrossJeffrey HarveyEmil Martinecand Ryan Rohm [1] the so-called "Princeton String Quartet" [2]in one of the key papers that fueled the first superstring revolution. The mismatched 16 dimensions must be compactified on an even, self-dual lattice a discrete subgroup of a linear space.

There are two possible even self-dual lattices in 16 dimensions, and it leads to two types of the heterotic string. They differ by the gauge group in 10 dimensions. Every heterotic string must be a closed stringnot an open string ; it is not possible to define any boundary conditions that would relate the left-moving and the right-moving excitations because they have a different character. String duality is a class of symmetries in physics that link different string theories.

In the s, it was realized that the strong coupling limit of the HO theory is type I string theory — a theory that also contains open strings ; this relation is called S-duality.

**Xenia de la Ossa - Moduli spaces in heterotic string theory**

Because the various superstring theories were shown to be related by dualities, it was proposed that each type of string was a different limit of a single underlying theory called M-theory. From Wikipedia, the free encyclopedia. This article is about string theory. For heterosis in biology, see Heterosis.

Related concepts. Physical Review Letters.

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The New York Times. Retrieved String Theory: Volume 2p. String theory. Strings History of string theory First superstring revolution Second superstring revolution String theory landscape.

T-duality S-duality U-duality Montonen—Olive duality. Kaluza—Klein theory Compactification Why 10 dimensions? Supergravity Superspace Lie superalgebra Lie supergroup. Matrix theory Introduction to M-theory. Categories : String theory E8 mathematics. Namespaces Article Talk. Views Read Edit View history. Help Learn to edit Community portal Recent changes Upload file.

Download as PDF Printable version. String Brane D-brane. Phenomenology Cosmology Landscape. Mirror symmetry Monstrous moonshine. History Glossary.See hybrid vigor. All rights reserved. References in periodicals archive?

Heterotic studies and inbreeding depression in F2 populations of upland cotton. Heritability estimates, specific combining ability, dominance effects and heterotic effects provide a reliable opportunity to develop hybrid varieties. Genome methylation level of the Larix kaempferi heterotic hybrids may play critical role in the formation of heterosis.

Higher magnitude of heterotic effects and superior hybrids can be developed by combining diverse parents. In this realisation, the untwisted vector bosons corresponding to the sixteen-dimensional vector bundle of the heterotic string in ten dimensions generate an SO[ 8. An understanding of genetic relationships among inbred lines or pure lines can be particularly useful in planning crosses, in assigning lines to specific heterotic groups, and for precise identification with respect to plant varietal protection Hallauer and Miranda, This shows more heterotic potential in these three combinations.

Genetic diversity in peach cultivars. Dictionary browser? Full browser?I'm a final year DPhil student working in the particle theory group. More specifically I work with the string theory group under Andre Lukas. My research focuses on string model-building and string dualities, primarily models in heterotic string theory, and the duality between heterotic string theory and F-theory.

More information can be found under the 'Research' tab. Tutor for Brasenose College, University of Oxford January - Present Tutor to third year physics students in advanced classical mechanics. My areas of research are string model-building and string dualities. Two of the string theory frameworks in which I have worked most heavily are heterotic string theory and F-theory.

With Braun and Lukas, I built phenomenologically interesting heterotic string models in a novel class of situations. We extended the existing toolbox to new classes of manifolds, and performed a systematic search for phenomenologically interesting models.

## Callum Brodie

Using powerful tools from algebraic geometry we determined which models were phenomenologically interesting. As these models did not have a standard dual, we conjectured an extension of the duality and we performed many non-trivial checks of the conjecture.

NS5-branes are a required ingredient in heterotic model-building, but the F-theory duals had not been extensively explored. We included NS5-branes systematically, and constructed the corresponding F-theory models. We also detailed many non-trivial aspects of the duality for these objects.

We also described the F-theory dual of intersecting or coincident NS5-branes. This is an ingredient in heterotic models that has not been explored, but which would give a completely new sector to utilise in model-building. We described in detail the dual F-theory picture, making explicit the global F-theory geometry.

This dual picture has the potential to further the understanding of these objects in heterotic string theory. These extensions would allow the duality to be used for new classes of models, and would give a much richer understanding of this duality.

I am also currently pursuing research on constructing SU 3 structures on internal spaces for model-building. The construction of these would allow the use of differential geometry tools to be systematically applied for the first time in this context. This in turn would allow for the first time the computation of quantities like Yukawa couplings which are crucial for model-building efforts. These are promising areas with important consequences for our understanding of string dualities and model-building.

Visit my research group website Contact details Callum Brodie is no longer affiliated with the department. This page is here for archival purposes only.May be a bit light for some but that is personal preference.

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