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Ralph Blumenhagen - One of the best experts on this subject based on the ideXlab platform.

  • D-Branes and Orientifolds
    Strings and Fundamental Physics, 2012
    Co-Authors: Ralph Blumenhagen
    Abstract:

    In this lecture we describe the conformal field theory describing the dynamics of open strings. Their end-points define submanifolds in the target space, which turn out to be dynamical and give rise the notion of D-branes. In CFT they are described by so-called boundary states, which we discuss in some detail. In addition, quotients by the world-sheet Parity Transformation are discussed leading to orientifolds, whose prime example is the type I string. This lecture is part of (Blumenhagen, Lect. Notes Phys. 779:1–256, 2009) and is just a first introduction into the subject focusing on open bosonic strings, where most of the relevant material can be explained. The generalization to superstrings is fairly straightforward.

  • A note on partition functions of Gepner model orientifolds
    Physics Letters B, 2004
    Co-Authors: Ralph Blumenhagen, Timo Weigand
    Abstract:

    AbstractIn this note we generalize the description of simple current extended Gepner model orientifolds as presented in hep-th/0401148 on the case of even levels and non-trivial dressings of the Parity Transformation. We provide a comprehensive list of all the important ingredients for the construction of such orientifolds. Namely we present explicit expressions for the Klein-bottle, annulus and Möbius strip amplitudes and derive the general tadpole cancellation conditions. As an example we construct a supersymmetric Pati–Salam like model

  • A New Class of Supersymmetric Orientifolds with D-branes at Angles
    Proceedings of Quantum aspects of gauge theories supersymmetry and unification — PoS(tmr99), 2000
    Co-Authors: Ralph Blumenhagen, Lars Gorlichand, Boris Körs
    Abstract:

    We describe a new class of supersymmetric orientifolds which combine the world-sheet Parity Transformation with a complex conjugation in the compact directions. As an example, we investigate in detail the orientifold of the Z3 toroidal orbifold in six and four dimensions. We demonstrate how the solution to the tadpole cancellation conditions, the resulting gauge groups and the massless spectra depend on the choice of the complex structures on the tori, giving rise to a variety of inequivalent models. We also summarize the results for the orientifolds of the Z4, Z6,and Z 0 orbifolds in four and six dimensions.

  • Supersymmetric 4D orientifolds of Type IIA with D6-branes at angles
    Journal of High Energy Physics, 2000
    Co-Authors: Ralph Blumenhagen, Lars Görlich, Boris Körs
    Abstract:

    We study a certain class of four-dimensional = 1 supersymmetric orientifolds for which the world-sheet Parity Transformation is combined with a complex conjugation in the compact directions. We investigate in detail the orientifolds of the 3, 4, 6 and 6' toroidal orbifolds finding solutions to the tadpole cancellation conditions for all models. Generically, all the massless spectra turn out to be non-chiral.

  • Discrete deformations in Type I vacua
    Physics Letters B, 2000
    Co-Authors: Carlo Angelantonj, Ralph Blumenhagen
    Abstract:

    Abstract We study supersymmetric orientifolds where the world-sheet Parity Transformation is combined with a conjugation of some compact complex coordinates. We investigate their T-duality relation to standard orientifolds and discuss the origin of continuous and discrete moduli. In contrast to standard orientifolds, the antisymmetric tensor describes a continuous deformation, while the off-diagonal part of the metric is frozen to quantized values and is responsible for the rank reduction of the gauge group. We also give a geometrical interpretation of some recently constructed six-dimensional permutational orientifolds.

Boris Körs - One of the best experts on this subject based on the ideXlab platform.

  • A New Class of Supersymmetric Orientifolds with D-branes at Angles
    Proceedings of Quantum aspects of gauge theories supersymmetry and unification — PoS(tmr99), 2000
    Co-Authors: Ralph Blumenhagen, Lars Gorlichand, Boris Körs
    Abstract:

    We describe a new class of supersymmetric orientifolds which combine the world-sheet Parity Transformation with a complex conjugation in the compact directions. As an example, we investigate in detail the orientifold of the Z3 toroidal orbifold in six and four dimensions. We demonstrate how the solution to the tadpole cancellation conditions, the resulting gauge groups and the massless spectra depend on the choice of the complex structures on the tori, giving rise to a variety of inequivalent models. We also summarize the results for the orientifolds of the Z4, Z6,and Z 0 orbifolds in four and six dimensions.

  • Supersymmetric 4D orientifolds of Type IIA with D6-branes at angles
    Journal of High Energy Physics, 2000
    Co-Authors: Ralph Blumenhagen, Lars Görlich, Boris Körs
    Abstract:

    We study a certain class of four-dimensional = 1 supersymmetric orientifolds for which the world-sheet Parity Transformation is combined with a complex conjugation in the compact directions. We investigate in detail the orientifolds of the 3, 4, 6 and 6' toroidal orbifolds finding solutions to the tadpole cancellation conditions for all models. Generically, all the massless spectra turn out to be non-chiral.

  • Supersymmetric orientifolds in 6D with D-branes at angles
    Nuclear Physics B, 2000
    Co-Authors: Ralph Blumenhagen, Lars Görlich, Boris Körs
    Abstract:

    We study a new class of N=1 supersymmetric orientifolds in six space-time dimensions. The world-sheet Parity Transformation is combined with a permutation of the internal complex coordinates. In contrast to ordinary orientifolds the twisted sectors contribute to the Klein bottle amplitude leading to new tadpoles to be cancelled by twisted open string sectors. They arise from open strings stretched between D7-branes intersecting at non-trivial angles. We study in detail the Z_3, Z_4 and Z_6 permutational orientifolds obtaining in all cases anomaly free massless spectra.Comment: 23 pages, TeX, harvmac, 9 figures, intro changed, ref. added, Z_6 spectrum slightly change

  • Supersymmetric orientifolds in 6D with D-branes at angles
    Nuclear Physics, 1999
    Co-Authors: Ralph Blumenhagen, Lars Görlich, Boris Körs
    Abstract:

    Abstract We study a new class of N=1 supersymmetric orientifolds in six space-time dimensions. The world-sheet Parity Transformation is combined with a permutation of the internal complex coordinates. In contrast to ordinary orientifolds the twisted sectors contribute to the Klein bottle amplitude leading to new tadpoles to be cancelled by twisted open string sectors. They arise from open strings stretched between D7-branes intersecting at non-trivial angles. We study in detail the Z 3 , Z 4 and Z 6 permutational orientifolds obtaining in all cases anomaly free massless spectra.

Lars Görlich - One of the best experts on this subject based on the ideXlab platform.

  • Supersymmetric 4D orientifolds of Type IIA with D6-branes at angles
    Journal of High Energy Physics, 2000
    Co-Authors: Ralph Blumenhagen, Lars Görlich, Boris Körs
    Abstract:

    We study a certain class of four-dimensional = 1 supersymmetric orientifolds for which the world-sheet Parity Transformation is combined with a complex conjugation in the compact directions. We investigate in detail the orientifolds of the 3, 4, 6 and 6' toroidal orbifolds finding solutions to the tadpole cancellation conditions for all models. Generically, all the massless spectra turn out to be non-chiral.

  • Supersymmetric orientifolds in 6D with D-branes at angles
    Nuclear Physics B, 2000
    Co-Authors: Ralph Blumenhagen, Lars Görlich, Boris Körs
    Abstract:

    We study a new class of N=1 supersymmetric orientifolds in six space-time dimensions. The world-sheet Parity Transformation is combined with a permutation of the internal complex coordinates. In contrast to ordinary orientifolds the twisted sectors contribute to the Klein bottle amplitude leading to new tadpoles to be cancelled by twisted open string sectors. They arise from open strings stretched between D7-branes intersecting at non-trivial angles. We study in detail the Z_3, Z_4 and Z_6 permutational orientifolds obtaining in all cases anomaly free massless spectra.Comment: 23 pages, TeX, harvmac, 9 figures, intro changed, ref. added, Z_6 spectrum slightly change

  • Supersymmetric orientifolds in 6D with D-branes at angles
    Nuclear Physics, 1999
    Co-Authors: Ralph Blumenhagen, Lars Görlich, Boris Körs
    Abstract:

    Abstract We study a new class of N=1 supersymmetric orientifolds in six space-time dimensions. The world-sheet Parity Transformation is combined with a permutation of the internal complex coordinates. In contrast to ordinary orientifolds the twisted sectors contribute to the Klein bottle amplitude leading to new tadpoles to be cancelled by twisted open string sectors. They arise from open strings stretched between D7-branes intersecting at non-trivial angles. We study in detail the Z 3 , Z 4 and Z 6 permutational orientifolds obtaining in all cases anomaly free massless spectra.

  • Orientifolds of non-supersymmetric, asymmetric orbifolds
    Nuclear Physics B, 1999
    Co-Authors: Ralph Blumenhagen, Lars Görlich
    Abstract:

    We consider certain four-dimensional supersymmetric and non-supersymmetric asymmetric orbifolds with vanishing cosmological constant up to two loops and gauge the world-sheet Parity Transformation. This leads to new string vacua, in which Dp- and D(p - 4)-branes or Dp and D(p-4) are identified. Moreover, it is shown that different degrees of supersymmetry can be realized in the bulk and on the brane. We show that for non-supersymmetric models the cosmological constant still vanishes at one-loop order.

Jian-bo Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Topological charge evolution in the Markov chain of QCD
    Physics Letters B, 2004
    Co-Authors: Derek B. Leinweber, Anthony G. Williams, Jian-bo Zhang
    Abstract:

    The topological charge is studied on lattices of large physical volume and fine lattice spacing. We illustrate how a Parity Transformation on the SU(3) link-variables of lattice gauge configurations reverses the sign of the topological charge and leaves the action invariant. Random applications of the Parity Transformation are proposed to traverse from one topological charge sign to the other. The Transformation provides an improved unbiased estimator of the ensemble average and is essential in improving the ergodicity of the Markov chain process.

  • Topological charge evolution in the Markov chain of QCD
    Physics Letters B, 2004
    Co-Authors: Derek B. Leinweber, Jian-bo Zhang, Anthony G. Williams, Frank X. Lee
    Abstract:

    Copyright © 2004 Elsevier B.V. All rights reserved. Printed in U.S.A. Submitted to Cornell University’s online archive www.arXiv.org in 2004 by Jianbo Zhang. Post-print sourced from www.arxiv.org.The topological charge is studied on lattices of large physical volume and fine lattice spacing. We illustrate how a Parity Transformation on the SU(3) link-variables of lattice gauge configurations reverses the sign of the topological charge and leaves the action invariant. Random applications of the Parity Transformation are proposed to traverse from one topological charge sign to the other. The Transformation provides an improved unbiased estimator of the ensemble average and is essential in improving the ergodicity of the Markov chain process.Derek B. Leinweber, Anthony G. Williams, Jian-Bo Zhang and Frank X. Leehttp://www.elsevier.com/wps/find/journaldescription.cws_home/505706/description#descriptio

Derek B. Leinweber - One of the best experts on this subject based on the ideXlab platform.

  • Topological charge evolution in the Markov chain of QCD
    Physics Letters B, 2004
    Co-Authors: Derek B. Leinweber, Anthony G. Williams, Jian-bo Zhang
    Abstract:

    The topological charge is studied on lattices of large physical volume and fine lattice spacing. We illustrate how a Parity Transformation on the SU(3) link-variables of lattice gauge configurations reverses the sign of the topological charge and leaves the action invariant. Random applications of the Parity Transformation are proposed to traverse from one topological charge sign to the other. The Transformation provides an improved unbiased estimator of the ensemble average and is essential in improving the ergodicity of the Markov chain process.

  • Topological charge evolution in the Markov chain of QCD
    Physics Letters B, 2004
    Co-Authors: Derek B. Leinweber, Jian-bo Zhang, Anthony G. Williams, Frank X. Lee
    Abstract:

    Copyright © 2004 Elsevier B.V. All rights reserved. Printed in U.S.A. Submitted to Cornell University’s online archive www.arXiv.org in 2004 by Jianbo Zhang. Post-print sourced from www.arxiv.org.The topological charge is studied on lattices of large physical volume and fine lattice spacing. We illustrate how a Parity Transformation on the SU(3) link-variables of lattice gauge configurations reverses the sign of the topological charge and leaves the action invariant. Random applications of the Parity Transformation are proposed to traverse from one topological charge sign to the other. The Transformation provides an improved unbiased estimator of the ensemble average and is essential in improving the ergodicity of the Markov chain process.Derek B. Leinweber, Anthony G. Williams, Jian-Bo Zhang and Frank X. Leehttp://www.elsevier.com/wps/find/journaldescription.cws_home/505706/description#descriptio