Ref HAL: hal-03929817_v1
DOI: 10.1002/ADMI.201700984
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Résumé:

Chemical vapor deposition (CVD) processes had been around for nearly 100 years before they began to attract interest from materials scientists and electronics engineers in the 60s and 70s, as a result of the rapidly growing microelectronics industry. The successful development of this complicated technology required a deep physicochemical understanding of deposition processes and reaction mechanisms. This resulted in a large number of scientists from different disciplines studying the basics of CVD...

Résumé:

I'll discuss the modular properties of D3-brane instantons appearing in Calabi-Yau string compactifications. I'll show that the D3-instanton contribution to a certain geometric potential on the hypermultiplet moduli space can be related to the elliptic genus of (0,4) SCFT. The modular properties of the potential imply that the elliptic genus associated with non-primitive divisors of Calabi-Yau is only mock modular. I'll show how to construct its modular completion and to make manifest the modular invariance of the twistorial construction of D-instanton corrected hypermultiplet moduli space.

Ref HAL: hal-01627837_v1
Ref Arxiv: 1710.10665
DOI: 10.1007/JHEP01(2018)156
WoS: WOS:000423794700001
Ref. & Cit.: NASA ADS
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8 Citations
Résumé:

We study the rigid limit of a class of hypermultiplet moduli spaces appearing in Calabi-Yau compactifications of type IIB string theory, which is induced by a local limit of the Calabi-Yau. We show that the resulting hyperkahler manifold is obtained by performing a hyperkahler quotient of the Swann bundle over the moduli space, along the isometries arising in the limit. Physically, this manifold appears as the target space of the non-linear sigma model obtained by compactification of a five-dimensional gauge theory on a torus. This allows to compute dyonic and stringy instantons of the gauge theory from the known results on D-instantons in string theory. Besides, we formulate a simple condition on the existence of a non-trivial local limit in terms of intersection numbers of the Calabi-Yau, and find an explicit form for the hypermultiplet metric including corrections from all mutually non-local D-instantons, which can be of independent interest.

Commentaires: 38+18+5 pages, 2 figures

Ref HAL: hal-01627846_v1
Ref Arxiv: 1702.05497
DOI: 10.1007/s00220-018-3114-z
WoS: WOS:000428927100008
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
7 Citations
Résumé:

We analyze the modular properties of D3-brane instanton corrections to the hypermultiplet moduli space in type IIB string theory compactified on a Calabi-Yau threefold. In Part I, we found a necessary condition for the existence of an isometric action of S-duality on this moduli space: the generating function of DT invariants in the large volume attractor chamber must be a vector-valued mock modular form with specified modular properties. In this work, we prove that this condition is also sufficient at two-instanton order. This is achieved by producing a holomorphic action of SL(2,Z) on the twistor space which preserves the holomorphic contact structure. The key step is to cancel the anomalous modular variation of the Darboux coordinates by a local holomorphic contact transformation, which is generated by a suitable indefinite theta series. For this purpose we introduce a new family of theta series of signature (2,n-2), find their modular completion, and conjecture sufficient conditions for their convergence, which may be of independent mathematical interest.

Commentaires: 24+24 pages

Ref HAL: hal-01443698_v1
Exporter : BibTex | endNote
Résumé:

I'll discuss the modular properties of D3-brane instantons appearing in Calabi-Yau string compactifications. I'll show that the D3-instanton contribution to a certain geometric potential on the hypermultiplet moduli space can be related to the elliptic genus of (0,4) SCFT. The modular properties of the potential imply that the elliptic genus associated with non-primitive divisors of Calabi-Yau is only mock modular. I'll show how to construct its modular completion and to make manifest the modular invariance of the twistorial construction of D-instanton corrected hypermultiplet moduli space.

Ref HAL: hal-02046929_v1
Exporter : BibTex | endNote
Résumé:

I’ll present an introduction to the problem of string theory compactifications with an emphasis on the low energy description of compactifications of type II strings on Calabi-Yau manifolds. In particular, I’ll describe the Kaluza-Klein reduction procedure, basic facts about Calabi-Yau manifolds and why they are important in string theory, effective actions arising in the low energy limit, their moduli spaces, their symmetries and dualities between them. Depending on time, I may also touch the problem of quantum corrections and compactifications with fluxes.

Résumé:

I'll present a review of what is known about effective low-energy theory arising as a result of compactification of string theory down to 4 dimensions. In particular, I'll discuss why Calabi-Yau manifolds naturally arise as internal compactification manifolds, what is known in this case about quantum corrections, and why these manifolds are not enough from the phenomenological point of view. If time permits, I'll also present basic facts about flux compactifications allowing to get more realistic models.