Dieter Lüst

CERN, Genève, Geneva, Switzerland

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Publications (165)583.87 Total impact

  • Source
    Gia Dvali · Cesar Gomez · Dieter Luest
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    ABSTRACT: Black hole entropy, denoted by N, in (semi)classical limit is infinite. This scaling reveals a very important information about the qubit degrees of freedom that carry black hole entropy. Namely, the multiplicity of qubits scales as N, whereas their energy gap and their coupling as 1/N. Such a behavior is indeed exhibited by Bogoliubov-Goldstone degrees of freedom of a quantum-critical state of N soft gravitons (a condensate or a coherent state) describing the black hole quantum portrait. They can be viewed as the Goldstone modes of a broken symmetry acting on the graviton condensate. In this picture Minkowski space naturally emerges as a coherent state of infinite-N gravitons of infinite wavelength and it carries an infinite entropy. In this paper we ask what is the geometric meaning (if any) of the classical limit of this symmetry. We argue that the infinite-N limit of Bogoliubov-Goldstone modes of critical graviton condensate is described by recently-discussed classical BMS super-translations broken by the black hole geometry. However, the full black hole information can only be recovered for finite N, since the recovery time becomes infinite in classical limit in which N is infinite.
    Preview · Article · Sep 2015 · Physics Letters B
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    ABSTRACT: We find static spherically symmetric solutions of scale invariant R 2 gravity. The latter has been shown to be equivalent to General Relativity with a positive cosmological constant and a scalar mode. Therefore, one expects that solutions of the R 2 theory will be identical to that of Einstein theory. Indeed, we find that the solutions of R 2 gravity are in one-to-one correspondence with solutions of General Relativity in the case of non-vanishing Ricci scalar. However, scalar-flat R = 0 solutions are global minima of the R 2 action and they cannot in general be mapped to solutions of the Einstein theory. As we will discuss, the R = 0 solutions arise in Einstein gravity as solutions in the tensionless, strong coupling limit M P → 0. As a further result, there is no corresponding Birkhoff theorem and the Schwarzschild black hole is by no means unique in this framework. In fact, R 2 gravity has a rich structure of vacuum static spherically symmetric solutions partially uncovered here. We also find charged static spherically symmetric backgrounds coupled to a U(1) field. Finally, we provide the entropy and energy formulas for the R 2 theory and we find that entropy and energy vanish for scalar-flat backgrounds.
    Preview · Article · May 2015 · Journal of High Energy Physics
  • Source
    Costas Kounnas · Dieter Lüst · Nicolaos Toumbas
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    ABSTRACT: The ${\cal R}^2$ scale invariant gravity theory coupled to conformally invariant matter is investigated. We show that in the non-supersymmetric case the conformally coupled scalars belong to an $SO(1, 1+n)/SO(1+n)$ manifold, while in the supersymmetric case the scalar manifold becomes isomorphic to the K\"ahlerian space ${\cal M}_n$=$SU(1, 1+n)/ U(1)\times SU(1+n)$. In both cases when the underlying scale symmetry is preserved the vacuum corresponds to de Sitter space. Once the scale symmetry is broken by quantum effects, a transition to flat space becomes possible. We argue that the scale violating terms are induced by anomalies related to a $U(1)_R$ symmetry. The anomaly is resolved via the gauging of a Peccei-Quinn axion shift symmetry. The theory describes an inflationary transition from de Sitter to flat Minkowski space, very similar to the Starobinsky inflationary model. The extension to metastable de Sitter superstring vacua is also investigated. The scalar manifold is extended to a much richer manifold, but it contains always ${\cal M}_n$ as a sub-manifold. In superstrings the metastability is induced by axions that cure the anomalies in chiral $N=1$ (or even $N=0$) supersymmetric vacua via a Green-Schwarz/Peccei-Quinn mechanism generalized to four dimensions. We present some typical superstring models and discuss the possible stabilization of the no-scale modulus.
    Full-text · Article · Sep 2014 · Fortschritte der Physik
  • Falk Haßler · Dieter Lüst
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    ABSTRACT: In this paper we discuss the construction of non-geometric Q- and R-branes as sources of non-geometric Q- and R-fluxes in string compactifications. The non-geometric Q-branes, being obtained via T-duality from the NS 5-brane or respectively from the KK-monopole, are still local solutions of the standard NS action, where however the background fields G and B possess non-geometric global monodromy properties. We show that using double field theory and redefined background fields $ \widetilde{G} $ and β as well as their corresponding effective action, the Q-branes are locally and globally well behaved solutions. Furthermore the R-brane solution can be at least formally constructed using dual coordinates. We derive the associated non-geometric Q- and R-fluxes and discuss that closed strings moving in the space transversal to the world-volumes of the non-geometric branes see a non-commutative or a non-associative geometry. In the second part of the paper we construct intersecting Q- and R-brane configurations as completely supersymmetric solutions of type IIA/B supergravity with certain SU(3) × SU(3) group structures. In the near horizon limit the intersecting brane configurations lead to type II backgrounds of the form AdS 4 × M 6, where the six-dimensional compact space M 6 is a torus fibration with various non-geometric Q- and R-fluxes in the compact directions. It exhibits an interesting non-commutative and non-associate geometric structure. Furthermore we also determine some of the effective four-dimensional superpotentials originating from the non-geometric fluxes.
    No preview · Article · Jul 2013 · Journal of High Energy Physics
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen

    No preview · Article · Jan 2013
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    ABSTRACT: We discuss the phenomenology and cosmology of a Standardlike Model inspired by string theory, in which the gauge fields are localized on D-branes wrapping certain compact cycles on an underlying geometry, whose intersection can give rise to chiral fermions. The energy scale associated with string physics is assumed to be near the Planck mass. To develop our program in the simplest way, we work within the construct of a minimal model with gauge-extended sector U(3)B×Sp(1)L×U(1)IR×U(1)L. The resulting U(1) content gauges the baryon number B, the lepton number L, and a third additional Abelian charge IR which acts as the third isospin component of an SU(2)R. All mixing angles and gauge couplings are fixed by rotation of the U(1) gauge fields to a basis diagonal in hypercharge Y and in an anomaly-free linear combination of IR and B-L. The anomalous Z′ gauge boson obtains a string scale Stückelberg mass via a 4D version of the Green-Schwarz mechanism. To keep the realization of the Higgs mechanism minimal, we add an extra SU(2) singlet complex scalar, which acquires a VEV and gives a TeV-scale mass to the nonanomalous gauge boson Z′′. The model is fully predictive and can be confronted with dijet and dilepton data from LHC8 and, eventually, LHC14. We show that MZ′′≈3–4 TeV saturates current limits from the CMS and ATLAS Collaborations. We also show that for MZ′′≲5 TeV, LHC14 will reach discovery sensitivity ≳5σ. After that, we demonstrate in all generality that Z′′ milliweak interactions could play an important role in observational cosmology. Finally, we examine some phenomenological aspects of the supersymmetric extension of the D-brane construct.
    No preview · Article · Jun 2012 · Physical review D: Particles and fields
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: Type II compactifications with D-branes and background fluxes are viable candidates to relate string theory to the physics we observe in four dimensions. For simple toroidal orbifold backgrounds the D-brane and orientifold sector can be described by an exact CFT, but issues such as tadpole cancellation, the Green-Schwarz mechanism, determining the massless spectrum etc. arise in a broader context and can be discussed from the low-energy-effective action perspective. String compactifications with non-vanishing NS-NS and R-R p-form field strengths provide solutions to the moduli problem, as these background fluxes modify the string equations of motion at leading order so that its solutions generically generate a potential for the would-be moduli fields. Thus they receive a vacuum expectation value and a mass. Basic knowledge of \(\mathcal{N} = 1\)supersymmetry in four dimensions is assumed.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: The fermionic string is quantized analogously to the bosonic string, though this time leading to a critical dimension d = 10. We first quantize in light-cone gauge and construct the spectrum. To remove the tachyon one has to perform the so-called GSO projection, which guarantees space-time supersymmetry of the ten-dimensional theory. There are two possible space-time supersymmetric GSO projections which result in the type IIA and the type IIB superstring. We also present the covariant path integral quantization. The chapter closes with an appendix on spinors in ddimensions.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: As another application of conformal field theory, we want to examine the reparametrization ghosts which we introduced within the path integral quantization of the bosonic string in Chap. 3. In the second part of this chapter we briefly study the very much related issue of BRST quantization of the bosonic string, where we encounter another characterization of physical string states, namely as states in the cohomology of a nilpotent BRST charge.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: In the first part of this chapter we compute the one-loop partition function of the closed fermionic string. We will do this in light cone gauge. The possibility to assign to the world-sheet fermions periodic or anti-periodic boundary conditions leads to the concept of spin structures. The requirement of modular invariance is then shown to result in the GSO projection. We also generalize some of the results of Chap. 6 to the case of fermions. We then consider open superstrings, i.e. we extend the formalism of conformal field theories with boundaries to include free fermionic fields. This gives rise to D-branes in superstring theories. We also discuss non-oriented superstrings, which result form performing a quotient of the type IIB superstring by the world-sheet parity transformation. We show that one-loop diagrams are divergent unless D-branes are present in the model. This defines the type I superstring, whose construction we discuss in some detail.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: So far we discussed the 26-dimensional bosonic string and three kinds of 10-dimensional superstring theories, the type IIA/B theories and the type I theory. One option to make contact with the four-dimensional world is to compactify the closed string theories on compact spaces. We first study the simplest examples, toroidal compactifications of the bosonic string and the type II superstring theories. These feature a new symmetry, called T-duality. To break supersymmetry, however, one has to compactify on non-flat spaces. The simplest such class are toroidal orbifolds. Moreover, we introduce two additional superstring theories in ten-dimensions, which are hybrid theories of a right-moving superstring and a left-moving bosonic string, whose additional sixteen dimensions are compactified on the weight-lattice of \(\mathrm{Spin}(32)/{\mathbb{Z}}_{2}\)or \({E}_{8} \times {E}_{8}\). We then study D-branes on toroidal spaces and how they transform under T-duality. We introduce intersecting D-branes, their T-dual images and simple orientifolds on such toroidal spaces.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen

    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: In the previous chapter we have learned that in toroidal compactifications of the bosonic string there are, in addition to the Kaluza-Klein gauge bosons familiar from field theory, further massless vectors of purely stringy origin. However, we did not show that these massless vectors are gauge bosons of a non-Abelian gauge group G, transforming in the adjoint representation. The necessary mathematical tool to do this is the theory of infinite dimensional (current) algebras, the so-called affine Kač-Moody algebras. They are the subject of this chapter for which we assume some familiarity with the structure of finite dimensional Lie algebras.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: In this chapter the quantization of the bosonic string is discussed. This leads to the notion of a critical dimension (d= 26) in which the bosonic string can consistently propagate. Its discovery was of great importance for the further development of string theory. We will discuss both the quantization in so-called light-cone gauge and the covariant path integral quantization, which leads to the introduction of ghost fields.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: In Chap. 4 we have demonstrated the usefulness of conformal field theory as a tool for the bosonic string. In the same way as conformal symmetry was a remnant of the reparametrization invariance of the bosonic string in conformal gauge, superconformal invariance is a remnant of local supersymmetry of the fermionic string in super-conformal gauge. This leads us to consider superconformal field theory. In many aspects our discussion of superconformal field theory parallels that of conformal field theory, and we will treat those rather briefly. Of special interest are N = 2 superconformal field theories, as they are related to space-time supersymmetry. These theories show some new features which we will present in more detail.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: To relate string theory to the usual description of particles and their interactions in terms of quantum field theories, it is important to have tools at hand to derive the effective point particle interactions for the massless excitation modes of the string. Such effective actions can be deduced from on-shell string scattering amplitudes which are computed as correlation functions of physical state vertex operators. We construct the vertex operators and compute various three-point functions which are needed to extract e.g. the interactions of graviton, two-form, dilaton and of gauge fields at leading order. We also compute the four-point functions of open and closed string tachyons and discuss some of their properties. Often the leading order (in α′) effective actions are already uniquely determined by symmetries, such as gauge symmetries or supersymmetry. We present the bosonic sectors of the ten-dimensional supergravity theories which are related to the ten-dimensional superstring theories. We also include a discussion of eleven-dimensional supergravity. The Dirac-Born-Infeld action, which governs the dynamics of the gauge field on a D-brane, will also be discussed.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: In this chapter we present various conformal field theory constructions which describe string theories in six and four space-time dimensions. We start with some general comments about strings moving in compactified spaces and then continue our investigation from Sect. 10.5 on strings in orbifold spaces. We then generalize the construction of non-oriented string theories to compact dimensions and discuss the prototype example of an orientifold on the compact space \({T}^{4}/{\mathbb{Z}}_{2}\). In this model we introduce fractional D-branes to cancel the tadpoles. Next, on a more abstract level, we outline the general structure a CFT must at least have in order to lead to a space-time supersymmetric compactification. Finally, we provide two concrete four dimensional realizations in terms of certain classes of \(N = 2\)superconformal field theories. The first are the so-called Gepner models and the second are heterotic generalizations of the covariant lattice approach from Chap. 13.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: Even though we will eventually be interested in a quantum theory of interacting strings, it will turn out to be useful to start two steps back and treat the free classical string. We will set up the Lagrangian formalism which is essential for the path integral quantization which we will treat in Chap. 3. We will then solve the classical equations of motion for single free closed and open strings. These solutions will be used for the canonical quantization which we will discuss in detail in the next chapter.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: We reexamine the 10-dimensional type II and heterotic superstring theories using the bosonic language. The aim of this bosonic formulation is the construction of the covariant fermion vertex operators, which involves a proper treatment of the \((\beta ,\gamma )\)ghost system, This will in turn lead to the introduction of the so-called covariant lattices.
    No preview · Chapter · Jan 2012
  • Ralph Blumenhagen · Dieter Lüst · Stefan Theisen
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    ABSTRACT: In this chapter we study issues of relevance for the perturbation theory of oriented bosonic strings. After giving a general description of world-sheets of higher genus, we discuss in some detail string one loop diagrams. We first do this for the closed string leading to torus diagrams, which we discuss both for the bosonic string and, continuing our presentation from Chap. 4, also for abstract conformal field theories. In this context we also present the simple current method, which provides a powerful tool for generating modular invariant partition functions. We also discuss the one-loop amplitude for open strings. From the one-loop amplitude of an open string stretched between two bosonic Dp-branes we extract the D-brane tension.
    No preview · Chapter · Jan 2012

Publication Stats

7k Citations
583.87 Total Impact Points

Institutions

  • 1989-2015
    • CERN
      • Physics Department (PH)
      Genève, Geneva, Switzerland
  • 1982-2015
    • Ludwig-Maximilians-University of Munich
      • Arnold Sommerfeld Center for Theoretical Physics (ASC)
      München, Bavaria, Germany
  • 1985-2014
    • Max Planck Institute of Physics
      München, Bavaria, Germany
  • 2010-2011
    • Technische Universität München
      München, Bavaria, Germany
  • 1993-2005
    • Humboldt-Universität zu Berlin
      • Department of Physics
      Berlín, Berlin, Germany
  • 1999
    • University of California, Santa Barbara
      • Kavli Institute for Theoretical Physics
      Santa Barbara, California, United States
  • 1986-1988
    • California Institute of Technology
      Pasadena, California, United States
  • 1983-1984
    • University Hospital München
      München, Bavaria, Germany