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Constantin, Andrei
Publications (9 of 9) Show all publications
Candelas, P., Constantin, A. & Mishra, C. (2018). Calabi-Yau Threefolds With Small Hodge Numbers. Fortschritte der Physik, 66(6), Article ID 1800029.
Open this publication in new window or tab >>Calabi-Yau Threefolds With Small Hodge Numbers
2018 (English)In: Fortschritte der Physik, ISSN 0015-8208, E-ISSN 1521-3978, Vol. 66, no 6, article id 1800029Article in journal (Refereed) Published
Abstract [en]

We present a list of Calabi-Yau threefolds known to us, and with holonomy groups that are precisely SU(3), rather than a subgroup, with small Hodge numbers, which we understand to be those manifolds with height (h1,1+h2,1)24. With the completion of a project to compute the Hodge numbers of free quotients of complete intersection Calabi‐Yau threefolds, most of which were computed in Refs. [1-3] and the remainder in Ref. [4], many new points have been added to the tip of the Hodge plot, updating the reviews by Davies and Candelas in Refs. [1, 5]. In view of this and other recent constructions of Calabi‐Yau threefolds with small height, we have produced an updated list.

National Category
Subatomic Physics
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:uu:diva-288084 (URN)10.1002/prop.201800029 (DOI)000436404500003 ()
Available from: 2016-04-27 Created: 2016-04-27 Last updated: 2018-08-24Bibliographically approved
Blesneag, S., Buchbinder, E. I., Constantin, A., Lukas, A. & Palti, E. (2018). Matter field Kahler metric in heterotic string theory from localisation. Journal of High Energy Physics (JHEP) (4), Article ID 139.
Open this publication in new window or tab >>Matter field Kahler metric in heterotic string theory from localisation
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2018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 4, article id 139Article in journal (Refereed) Published
Abstract [en]

We propose an analytic method to calculate the matter field Kahler metric in heterotic compactifications on smooth Calabi-Yau three-folds with Abelian internal gauge fields. The matter field Kahler metric determines the normalisations of the N = 1 chiral superfields, which enter the computation of the physical Yukawa couplings. We first derive the general formula for this Kahler metric by a dimensional reduction of the relevant supergravity theory and find that its T-moduli dependence can be determined in general. It turns out that, due to large internal gauge flux, the remaining integrals localise around certain points on the compactification manifold and can, hence, be calculated approximately without precise knowledge of the Ricci-flat Calabi-Yau metric. In a final step, we show how this local result can be expressed in terms of the global moduli of the Calabi-Yau manifold. The method is illustrated for the family of Calabi-Yau hypersurfaces embedded in P-1 x P-3 and we obtain an explicit result for the matter field Kahler metric in this case.

Keywords
Flux compactifications, Superstrings and Heterotic Strings
National Category
Subatomic Physics Other Physics Topics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-355469 (URN)10.1007/JHEP04(2018)139 (DOI)000432042300007 ()
Available from: 2018-06-29 Created: 2018-06-29 Last updated: 2018-06-29Bibliographically approved
Constantin, A., Gray, J. & Lukas, A. (2017). Hodge numbers for all CICY quotients. Journal of High Energy Physics (JHEP) (1), Article ID 001.
Open this publication in new window or tab >>Hodge numbers for all CICY quotients
2017 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 1, article id 001Article in journal (Refereed) Published
Abstract [en]

We present a general method for computing Hodge numbers for Calabi-Yau manifolds realised as discrete quotients of complete intersections in products of projective spaces. The method relies on the computation of equivariant cohomologies and is illustrated for several explicit examples. In this way, we compute the Hodge numbers for all discrete quotients obtained in Braun's classification [1].

Place, publisher, year, edition, pages
SPRINGER, 2017
Keywords
Differential and Algebraic Geometry, Superstring Vacua, Superstrings and Heterotic Strings, Space-Time Symmetries
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-320816 (URN)10.1007/JHEP01(2017)001 (DOI)000397640000001 ()
Available from: 2017-04-26 Created: 2017-04-26 Last updated: 2017-04-26Bibliographically approved
Candelas, P., Constantin, A. & Mishra, C. (2016). Hodge Numbers for CICYs with Symmetries of Order Divisible by 4. Fortschritte der Physik, 64(6-7), 463-509
Open this publication in new window or tab >>Hodge Numbers for CICYs with Symmetries of Order Divisible by 4
2016 (English)In: Fortschritte der Physik, ISSN 0015-8208, E-ISSN 1521-3978, Vol. 64, no 6-7, p. 463-509Article in journal (Refereed) Published
Abstract [en]

We compute the Hodge numbers for the quotients of complete intersection Calabi-Yau three-folds by groups of orders divisible by 4. We make use of the polynomial deformation method and the counting of invariant Kahler classes. The quotients studied here have been obtained in the automated classification of V. Braun. Although the computer search found the freely acting groups, the Hodge numbers of the quotients were not calculated. The freely acting groups, G, that arise in the classification are either Z(2) or contain Z(4), Z(2) x Z(2), Z(3) or Z(5) as a subgroup. The Hodge numbers for the quotients for which the group G contains Z(3) or Z(5) have been computed previously. This paper deals with the remaining cases, for which G superset of Z(4) or G superset of Z(2) x Z(2). We also compute the Hodge numbers for 99 of the 166 CICY's which have Z(2) quotients.

National Category
Subatomic Physics
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:uu:diva-288089 (URN)10.1002/prop.201600005 (DOI)000384837400002 ()
Available from: 2016-04-27 Created: 2016-04-27 Last updated: 2017-11-30Bibliographically approved
Constantin, A., Lukas, A. & Mishra, C. (2016). The Family Problem: Hints from Heterotic Line Bundle Models. Journal of High Energy Physics (JHEP) (3), Article ID 173.
Open this publication in new window or tab >>The Family Problem: Hints from Heterotic Line Bundle Models
2016 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 3, article id 173Article in journal (Refereed) Published
Abstract [en]

Within the class of heterotic line bundle models, we argue that N=1" role="presentation" style="display: inline; font-size: 13.6px; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; font-family: arial, verdana, sans-serif; position: relative;">=1N=1 vacua which lead to a small number of low-energy chiral families are preferred. By imposing an upper limit on the volume of the internal manifold, as required in order to obtain finite values of the four-dimensional gauge couplings, and validity of the supergravity approximation we show that, for a given manifold, only a finite number of line bundle sums are consistent with supersymmetry. By explicitly scanning over this finite set of line bundle models on certain manifolds we show that, for a sufficiently small volume of the internal manifold, the family number distribution peaks at small values, consistent with three chiral families. The relation between the maximal number of families and the gauge coupling is discussed, which hints towards a possible explanation of the family problem.

Keywords
space: internal | coupling: gauge | family | heterotic | chiral | supersymmetry | vacuum state | supergravity Author supplied: Superstring Vacua | Superstrings and Heterotic Strings
National Category
Subatomic Physics
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:uu:diva-288092 (URN)10.1007/JHEP03(2016)173 (DOI)000373221000001 ()
Available from: 2016-04-27 Created: 2016-04-27 Last updated: 2017-11-30Bibliographically approved
Candelas, P., Constantin, A., Damian, C., Larfors, M. & Morales, J. F. (2015). 4 Type IIB flux vacua from G-theory I. Journal of High Energy Physics (JHEP) (2), Article ID 187.
Open this publication in new window or tab >>4 Type IIB flux vacua from G-theory I
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2015 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 2, article id 187Article in journal (Refereed) Published
Abstract [en]

We construct non-perturbatively exact four-dimensional Minkowski vacua of type IIB string theory with non-trivial fluxes. These solutions are found by gluing together, consistently with U-duality, local solutions of type IIB supergravity on T-4 x C with the metric, dilaton and flux potentials varying along C and the flux potentials oriented along T-4. We focus on solutions locally related via U-duality to non-compact Ricci-flat geometries. More general solutions and a complete analysis of the supersymmetry equations are presented in the companion paper [1]. We build a precise dictionary between fluxes in the global solutions and the geometry of an auxiliary K3 surface fibered over CP1. In the spirit of F-theory, the flux potentials are expressed in terms of locally holomorphic functions that parametrize the complex structure moduli space of the K3 fiber in the auxiliary geometry. The brane content is inferred from the monodromy data around the degeneration points of the fiber.

Keywords
Flux compactifications, Superstring Vacua, String Duality
National Category
Other Physics Topics
Identifiers
urn:nbn:se:uu:diva-251522 (URN)10.1007/JHEP02(2015)187 (DOI)000350696300002 ()
Available from: 2015-04-22 Created: 2015-04-20 Last updated: 2017-12-04Bibliographically approved
Buchbinder, E. I., Constantin, A. & Lukas, A. (2015). Heterotic QCD axion. Physical Review D, 91(4), Article ID 046010.
Open this publication in new window or tab >>Heterotic QCD axion
2015 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 91, no 4, article id 046010Article in journal (Refereed) Published
Abstract [en]

In this paper, we show that there is no in-principle obstruction to obtain a Kim-Shifman-Vainshtein-Zakharov axion with a decay constant in the phenomenologically allowed range in certain E-8 x E-8 heterotic string models. These models have an enhanced symmetry locus in the moduli space and a nonuniversal, Kahler moduli-dependent Fayet-Iliopoulos term which vanishes at this locus. Close to this locus, the Fayet-Iliopoulos term is small and can lead to an axion decay constant significantly lower than the string scale. In this way, the no-go arguments of Svrcek and Witten, which are based on a universal, dilaton-dependent Fayet-Iliopoulos term, can be avoided. The relevant axion originates from phases of bundle moduli which correspond to deformations away from the enhanced symmetry locus. We construct an explicit example, based on a heterotic line bundle standard model, with all the required ingredients.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-248831 (URN)10.1103/PhysRevD.91.046010 (DOI)000350321200005 ()
Available from: 2015-04-08 Created: 2015-04-08 Last updated: 2017-12-04Bibliographically approved
Anderson, L. B., Constantin, A., Lee, S.-J. & Lukas, A. (2015). Hypercharge flux in heterotic compactifications. Physical Review D, 91(4), Article ID 046008.
Open this publication in new window or tab >>Hypercharge flux in heterotic compactifications
2015 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 91, no 4, article id 046008Article in journal (Refereed) Published
Abstract [en]

We study heterotic Calabi-Yau models with hypercharge flux breaking, where the visible E-8 gauge group is directly broken to the standard model group by a nonflat gauge bundle, rather than by a two-step process involving an intermediate grand unified theory and a Wilson line. It is shown that the required alternative E-8 embeddings of hypercharge, normalized as required for gauge unification, can be found and we classify these possibilities. However, for all but one of these embeddings we prove a general no-go theorem which asserts that no suitable geometry and vector bundle leading to a standard model spectrum can be found. Intuitively, this happens due to the large number of index conditions which have to be imposed in order to obtain a correct physical spectrum in the absence of an underlying grand unified theory.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-248840 (URN)10.1103/PhysRevD.91.046008 (DOI)000350257200004 ()
Available from: 2015-04-08 Created: 2015-04-08 Last updated: 2017-12-04Bibliographically approved
Candelas, P., Constantin, A., Damian, C., Larfors, M. & Morales, J. F. (2015). Type IIB flux vacua from G-theory II. Journal of High Energy Physics (JHEP) (2), Article ID 188.
Open this publication in new window or tab >>Type IIB flux vacua from G-theory II
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2015 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 2, article id 188Article in journal (Refereed) Published
Abstract [en]

We find analytic solutions of type IIB supergravity on geometries that locally take the form Mink x M-4 x C with M-4 a generalised complex manifold. The solutions involve the metric, the dilaton, NSNS and RR flux potentials (oriented along the M-4) parametrised by functions varying only over C. Under this assumption, the supersymmetry equations are solved using the formalism of pure spinors in terms of a finite number of holomorphic functions. Alternatively, the solutions can be viewed as vacua of maximally supersymmetric supergravity in six dimensions with a set of scalar fields varying holomorphically over C. For a class of solutions characterised by up to five holomorphic functions, we outline how the local solutions can be completed to four-dimensional flux vacua of type IIB theory. A detailed study of this global completion for solutions with two holomorphic functions has been carried out in the companion paper [1]. The fluxes of the global solutions are, as in F-theory, entirely codified in the geometry of an auxiliary K3 fibration over CP1. The results provide a geometric construction of fluxes in F-theory.

Keywords
Flux compactifications, Superstring Vacua, String Duality
National Category
Other Physics Topics
Identifiers
urn:nbn:se:uu:diva-251523 (URN)10.1007/JHEP02(2015)188 (DOI)000350696300003 ()
Available from: 2015-04-22 Created: 2015-04-20 Last updated: 2017-12-04Bibliographically approved
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