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58
Fourdimensional String Compactifications with DBranes, Orientifolds and Fluxes
"... This review article provides a pedagogical introduction into various classes of chiral string compactifications to four dimensions with Dbranes and fluxes. The main concern is to provide all necessary technical tools to explicitly construct fourdimensional orientifold vacua, with the final aim to ..."
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Cited by 147 (18 self)
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This review article provides a pedagogical introduction into various classes of chiral string compactifications to four dimensions with Dbranes and fluxes. The main concern is to provide all necessary technical tools to explicitly construct fourdimensional orientifold vacua, with the final aim to come as close as possible to the supersymmetric Standard Model. Furthermore, we outline the available methods to derive the resulting fourdimensional effective action. Finally, we summarize recent attempts to address the
Noncommutative compactifications of type I strings on tori with magnetic background flux
 JHEP 0010 (2000) 006, hepth/0007024; “Magnetic Flux in Toroidal Type I Compactification”, Fortsch. Phys. 49 (2001) 591, hepth/0010198
"... We construct six and fourdimensional toroidal compactifications of the Type I string with magnetic flux on the Dbranes. The open strings in this background probe a noncommutative internal geometry. Phenomenologically appealing features such as chiral fermions and supersymmetry breaking in the gau ..."
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Cited by 147 (27 self)
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We construct six and fourdimensional toroidal compactifications of the Type I string with magnetic flux on the Dbranes. The open strings in this background probe a noncommutative internal geometry. Phenomenologically appealing features such as chiral fermions and supersymmetry breaking in the gauge sector are naturally realized by these vacua. We investigate the spectra of such noncommutative string compactifications and in a bottomup approach discuss the possibility to obtain the standard or some GUT like model.
BPS Action and Superpotential for Heterotic String Compactifications with Fluxes
, 2003
"... We consider N = 1 compactifications to four dimensions of heterotic string theory in the presence of fluxes. We show that up to order O (α ′2) the associated action can be written as a sum of squares of BPSlike quantities. In this way we prove that the equations of motion are solved by backgrounds ..."
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Cited by 81 (4 self)
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We consider N = 1 compactifications to four dimensions of heterotic string theory in the presence of fluxes. We show that up to order O (α ′2) the associated action can be written as a sum of squares of BPSlike quantities. In this way we prove that the equations of motion are solved by backgrounds which fulfill the supersymmetry conditions and the Bianchi identities. We also argue for the expression of the related superpotential and discuss the radial modulus
A nogo theorem for string warped compactifications
, 2000
"... We give necessary conditions for the existence of perturbative heterotic and type II string warped compactifications preserving eight and four supersymmetries to four spacetime dimensions, respectively. In particular, we find that the only compactifications of heterotic string with the spin connecti ..."
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Cited by 60 (21 self)
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We give necessary conditions for the existence of perturbative heterotic and type II string warped compactifications preserving eight and four supersymmetries to four spacetime dimensions, respectively. In particular, we find that the only compactifications of heterotic string with the spin connection embedded in the gauge connection and type II strings are those on CalabiYau manifolds with constant dilaton. We obtain similar results for compactifications to six and to two dimensions.
A Standard Model from the E8 × E8 Heterotic Superstring
, 2005
"... In a previous paper, we introduced a heterotic standard model and discussed its basic properties. This vacuum has the spectrum of the MSSM with one additional pair of HiggsHiggs conjugate fields and a small number of uncharged moduli. In this paper, the requisite vector bundles are formulated; spec ..."
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Cited by 41 (17 self)
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In a previous paper, we introduced a heterotic standard model and discussed its basic properties. This vacuum has the spectrum of the MSSM with one additional pair of HiggsHiggs conjugate fields and a small number of uncharged moduli. In this paper, the requisite vector bundles are formulated; specifically, stable, holomorphic bundles with structure group SU(N) on smooth CalabiYau threefolds with Z3×Z3 fundamental group. A method for computing bundle cohomology is presented and used to evaluate the cohomology groups of the standard model bundles. It is shown how to determine the Z3 × Z3 action on these groups. Finally, using an explicit method of “doublettriplet splitting”, the lowenergy particle spectrum is computed.
Dbranes, fluxes and chirality
"... We describe a topological effect on configurations of Dbranes in the presence of NSNS and RR field strength fluxes. The fluxes induce the appearance of chiral anomalies on lower dimensional submanifolds of the Dbrane worldvolume. This anomaly is not associated to a dynamical chiral fermion degree ..."
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Cited by 28 (4 self)
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We describe a topological effect on configurations of Dbranes in the presence of NSNS and RR field strength fluxes. The fluxes induce the appearance of chiral anomalies on lower dimensional submanifolds of the Dbrane worldvolume. This anomaly is not associated to a dynamical chiral fermion degree of freedom, but rather should be regarded as an explicit fluxinduced anomalous term (WessZumino term) in the action. The anomaly is cancelled by an inflow mechanism, which exploits the fact that fluxes can act as sources of RR fields. We discuss several applications of this fluxinduced anomaly; among others, its role in understanding anomaly cancellation in compactifications with Dbranes and fluxes, and the possibility of phase transitions where a chiral fermion disappears from the Dbrane worldvolume spectrum, being replaced by an explicit WessZumino term. We comment on the relation among different mechanisms to obtain fourdimensional chirality in string theory. 1
Numerical Ricciflat metrics on K3
"... Preprint typeset in JHEP style HYPER VERSION ..."
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Vanishing Theorems and String Backgrounds
, 2000
"... We show various vanishing theorems for the cohomology groups of compact hermitian manifolds for which the Bismut connection has (restricted) holonomy contained in SU(n) and classify all such manifolds of dimension four. In this way we provide necessary conditions for the existence of such structures ..."
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Cited by 23 (1 self)
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We show various vanishing theorems for the cohomology groups of compact hermitian manifolds for which the Bismut connection has (restricted) holonomy contained in SU(n) and classify all such manifolds of dimension four. In this way we provide necessary conditions for the existence of such structures on hermitian manifolds. Then we apply our results to solutions of the string equations and show that such solutions admit various cohomological restrictions like for example that under certain natural assumptions the plurigenera vanish. We also find that under some assumptions the string equations are equivalent to the condition Riemannian manifolds equipped with a closed form have found many applications in various branches of mathematics and physics. In physics, the classical example is that of manifolds equipped with a closed twoform which describe gravity in the presence of a Maxwell field. More recently, Riemannian or pseudoRiemannian manifolds M equipped with (closed) forms
Exactly solvable (0, 2) supersymmetric string vacua with GUT gauge groups, Nucl. Phys. B454
, 1995
"... We present a construction of modular invariant partition functions for heterotic (0, 2) supersymmetric classical string vacua. This generalization of Gepner’s construction yields GUT gauge groups E6, SO(10), SU(5) and SU(3) × SU(2) × U(1) r, respectively. By calculating the massless spectrum of so ..."
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Cited by 18 (10 self)
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We present a construction of modular invariant partition functions for heterotic (0, 2) supersymmetric classical string vacua. This generalization of Gepner’s construction yields GUT gauge groups E6, SO(10), SU(5) and SU(3) × SU(2) × U(1) r, respectively. By calculating the massless spectrum of some of these models we find strong indications that they correspond to (0, 2) string vacua discussed recently in the context of CYM/LG phases. 1
Surface terms and the GaussBonnet Hamiltonian
, 2003
"... We derive the gravitational Hamiltonian starting from the GaussBonnet action, keeping track of all surface terms. This is done using the language of orthonormal frames and forms to keep things as tidy as possible. The surface terms in the Hamiltonian give a remarkably simple expression for the tota ..."
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Cited by 16 (4 self)
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We derive the gravitational Hamiltonian starting from the GaussBonnet action, keeping track of all surface terms. This is done using the language of orthonormal frames and forms to keep things as tidy as possible. The surface terms in the Hamiltonian give a remarkably simple expression for the total energy of a spacetime. This expression is consistent with energy expressions found in hepth/0212292. However, we can apply our results whatever the choice of background and whatever the symmetries of the spacetime.