DOCSLIB.ORG

The Cosmological Constant Problem, an Inspiration for New Physics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

ITP-UU-06/34 SPIN-06/30 gr-qc/yyxxxxx The Cosmological Constant Problem, an Inspiration for New Physics Stefan Nobbenhuis Ph.D. Thesis, defended June 15. 2006 Supervisor: Prof. Dr. G. ’t Hooft. Institute for Theoretical Physics Utrecht University, Leuvenlaan 4 3584 CC Utrecht, the Netherlands and Spinoza Institute Postbox 80.195 3508 TD Utrecht, the Netherlands [email protected] arXiv:gr-qc/0609011v1 4 Sep 2006 We have critically compared different approaches to the cosmological constant problem, which is at the edge of elementary particle physics and cosmology. This problem is deeply connected with the difficulties formulating a theory of quantum gravity. After the 1998 discovery that our universe’s expansion is accelerating, the cosmological constant problem has obtained a new dimension. We are mainly interested in the question why the cosmological constant is so small. We have identified four different classes of solutions: a symmetry, a back-reaction mechanism, a violation of (some of) the building blocks of general relativity, and statistical approaches. In this thesis we carefully study all known potential candidates for a solution, but conclude that so far none of the approaches gives a satisfactory solution. A symmetry would be the most elegant solution and we study a new symmetry under transformation to imaginary spacetime. Contents 1 The Cosmological Constant Problem 1 1.1 The ‘Old’ Problem, Vacuum Energy as Observable Effect . ........ 1 1.1.1 Reality of Zero-Point Energies . ... 5 1.1.2 RepulsiveGravity ............................. 5 1.2 TwoAdditionalProblems . 6 1.3 Renormalization ................................. 7 1.4 Interpretations of a Cosmological Constant . ......... 10 1.4.1 Cosmological Constant as Lagrange Multiplier . ....... 10 1.4.2 Cosmological Constant as Constant of Integration . ........ 10 1.5 WheretoLookforaSolution? . 11 1.5.1 Weinberg’s No-Go Theorem . 13 1.5.2 SomeOptimisticNumerology . 15 1.6 Outlineofthisthesis ............................. 16 2 Cosmological Consequences of Non-Zero Λ 19 2.1 TheExpandingUniverse. 19 2.1.1 SomeHistoricObjections . 22 2.2 Some Characteristics of FRW Models . ..... 23 2.2.1 Redshift................................... 25 2.3 TheEarlyUniverse................................ 28 2.3.1 Deriving Geometric Information from CMBR Anisotropies....... 31 2.3.2 EnergyDensityintheUniverse . 34 2.4 EvolutionoftheUniverse . 36 2.5 Precision cosmology in recent and upcoming experiments ........... 38 2.5.1 SupernovaeTypeIa ............................ 38 2.5.2 PioneerAnomaly.............................. 40 3 4 CONTENTS 3 Type I: Symmetry Mechanism 43 3.1 Supersymmetry................................... 44 3.1.1 No-ScaleSUGRA.............................. 45 3.1.2 UnbrokenSUSY .............................. 47 3.1.3 Non-SUSYStringModels .. .. .. .. .. .. .. 48 3.2 Scale Invariance, e.g. Conformal Symmetry . ........ 48 3.2.1 Λ as Integration Constant . 50 3.3 Holography ..................................... 51 3.3.1 Conceptual Issues in de Sitter Space . 53 3.4 “Symmetry” between Sub- and Super-Planckian Degrees of Freedom . 54 3.5 Interacting Universes, Antipodal Symmetry . ......... 56 3.6 DualityTransformations . 57 3.6.1 S-Duality .................................. 57 3.6.2 HodgeDuality ............................... 58 3.7 Summary ...................................... 58 4 Invariance Under Complex Transformations 59 4.1 Introduction.................................... 59 4.2 ClassicalScalarField. 60 4.3 Gravity ....................................... 61 4.4 Non-relativistic Particle . ...... 62 4.5 HarmonicOscillator .............................. 64 4.6 SecondQuantization .............................. 65 4.7 PureMaxwellFields ............................... 69 4.8 Relation with Boundary Conditions . ..... 70 4.9 RelatedSymmetries ............................... 72 4.9.1 Energy Energy ............................ 74 →− 4.10Summary ...................................... 75 5 Type II: Back-reaction 77 5.1 Scalar Field, Instabilities in dS-Space ...................... 77 5.1.1 ‘Cosmon’Screening ............................ 80 5.1.2 Radiative Stability in Scalar Field Feedback Mechanism........ 82 5.1.3 Dilaton ................................... 82 5.2 Instabilities of dS-Space.............................. 83 CONTENTS 5 5.2.1 Scalar-type Perturbations . 83 5.3 RunningΛfromRenormalizationGroup . ..... 87 5.3.1 Triviality as in λφ4 Theory ........................ 92 5.4 Screening as a Consequence of the Trace Anomaly . ....... 93 5.5 Summary ...................................... 94 6 Do Infrared Gravitons Screen the Cosmological Constant? 95 6.1 Introduction.................................... 95 6.2 AReviewoftheScenario ............................ 96 6.2.1 ANewtonianPicture............................ 98 6.3 Evaluation...................................... 99 6.4 The Full Quantum Gravitational Calculation . ........ 100 6.5 Renormalization in Perturbative QG . 105 6.6 Summary ...................................... 106 7 Type III: Violating the Equivalence Principle 109 7.1 Extra Dimensions, Braneworld Models . 109 7.2 Randall-Sundrum Models, Warped Extra Dimensions . ......... 110 7.2.1 Self-TuningSolutions . 112 7.2.2 ExtraTime-likeDimensions . 114 7.3 InfiniteVolumeExtraDimensions . 114 7.3.1 MassiveGravitons ............................. 121 7.3.2 Non-ZeroBraneWidth .......................... 124 7.3.3 Non-localGravity ............................. 124 7.3.4 A 5D DGP Brane-World Model . 126 7.4 Ghost Condensation or Gravitational Higgs Mechanism . .......... 126 7.5 FatGravitons.................................... 129 7.6 Composite Graviton as Goldstone boson . 131 7.6.1 Summary .................................. 132 8 Type IV: Statistical Approaches 135 8.1 HawkingStatistics ............................... 137 8.1.1 Wormholes ................................. 139 8.2 AnthropicPrinciple. .. .. .. .. .. .. .. .. 142 8.2.1 Anthropic Prediction for the Cosmological Constant . ......... 143 6 CONTENTS 8.2.2 Discrete vs. Continuous Anthropic Principle . ........ 146 8.3 Summary ...................................... 146 9 Conclusions 149 9.1 FutureEvolutionoftheUniverse . 150 A Conventions and Definitions 151 B Measured Values of Different Cosmological Parameters 153 B.1 HubbleConstant .................................. 153 B.2 TotalEnergyDensity.. .. .. .. .. .. .. .. .. 154 B.3 MatterintheUniverse. .. .. .. .. .. .. .. .. 154 B.4 DarkEnergyEquationofState . 154 B.5 Summary ...................................... 155 Bibliography 177 Chapter 1 The Cosmological Constant Problem In this chapter we carefully discuss the different aspects of the cosmological constant problem. How it occurs, what the assumptions are, and where the difficulties lie in renormalizing vacuum energy. Different interpretations of the cosmological constant have been proposed and we briefly discuss these. We subsequently, as a warm-up, point at some directions to look at for a solution, before ending this chapter by giving an outline of the rest of the thesis. 1.1 The ‘Old’ Problem, Vacuum Energy as Observable Effect 1 In quantum mechanics, the energy spectrum, En, of a simple harmonic oscillator is given by En = (n+1/2)ω. The energy of the ground state, the state with lowest possible energy, is non- zero, contrary to classical mechanics. This so-called zero-point energy is usually interpreted by referring to the uncertainty principle: a particle can never completely come to a halt. Free quantum field theory is formulated as an infinite series of simple harmonic oscillators. The energy density of the vacuum in for example free scalar field theory therefore receives an infinite positive contribution from the zero-point energies of the various modes of oscillation: 3 ∞ d k 1 2 2 ρ = 3 k + m , (1.1) h i 0 (2π) 2 Z p 2 2 and we set ω(k)= √k + m . With a UV-cutoff kmax, regularizing the a priori infinite value 2 4 for the vacuum energy density, this integral diverges as kmax. The filling of the ‘Dirac sea’ in the quantization of the free fermion theory leads to a downward shift in the vacuum energy with a similar ultraviolet divergence. The Hamiltonian is: 3 d k s s s s H = ω a †a b †b , (1.2) (2π)3 − s Z X 1See Appendix A for conventions and some definitions used throughout this thesis, e.g. ~ = 1. 2This is just the leading divergence, see section (1.3) for a more precise discussion. 1 2 CHAPTER 1. THE COSMOLOGICAL CONSTANT PROBLEM s where the bk† creates negative energy. Therefore we have to require that these operators satisfy anti-commutation relations: r s 3 (3) rs b , b †′ = (2π) δ (k k′)δ , (1.3) { k k } − r r since this is symmetric between b and b †, we can redefine the operators as follows: s s s s ˜b b †; ˜b † b , (1.4) ≡ ≡ which obey the same anti-commutation relations. Now the second term in the Hamiltonian becomes: kmax 3 s s s s d k ωb †b =+ω˜b †˜b (const.); (const) = ω(k). (1.5) − − (2π)3 Z Now we choose 0 to be the vacuum state that is annihilated by the as and ˜bs and all | i excitations have positive energy. All the negative energy states are filled; this is the Dirac sea. A hole in the sea corresponds to an excitation of the ground state with positive energy, compared to the ground state. The infinite constant contribution to the vacuum energy density has the same form as in the bosonic case, but enters with opposite sign. Spontaneous symmetry breaking gives a finite but still possibly large shift in the vacuum energy density. In this case, 1 = gµν ∂ φ∂ φ V (φ) (1.6) L 2 µ ν − where the potential
Recommended publications
  • Graviton J = 2

    Graviton J = 2

    Citation: M. Tanabashi et al. (Particle Data Group), Phys. Rev. D 98, 030001 (2018) graviton J = 2 graviton MASS Van Dam and Veltman (VANDAM 70), Iwasaki (IWASAKI 70), and Za- kharov (ZAKHAROV 70) almost simultanously showed that “... there is a discrete difference between the theory with zero-mass and a theory with finite mass, no matter how small as compared to all external momenta.” The resolution of this ”vDVZ discontinuity” has to do with whether the linear approximation is valid. De Rham etal. (DE-RHAM 11) have shown that nonlinear effects not captured in their linear treatment can give rise to a screening mechanism, allowing for massive gravity theories. See also GOLDHABER 10 and DE-RHAM 17 and references therein. Experimental limits have been set based on a Yukawa potential or signal dispersion. h0 − − is the Hubble constant in units of 100 kms 1 Mpc 1. − The following conversions are useful: 1 eV = 1.783 × 10 33 g = 1.957 × −6 × −7 × 10 me ; λ¯C = (1.973 10 m) (1 eV/mg ). VALUE (eV) DOCUMENT ID TECN COMMENT − <6 × 10 32 1 CHOUDHURY 04 YUKA Weak gravitational lensing ••• We do not use the following data for averages, fits, limits, etc. ••• − <7 × 10 23 2 ABBOTT 17 DISP Combined dispersion limit from three BH mergers − <1.2 × 10 22 2 ABBOTT 16 DISP Combined dispersion limit from two BH mergers − <5 × 10 23 3 BRITO 13 Spinningblackholesbounds − <4 × 10 25 4 BASKARAN 08 Graviton phase velocity fluctua- − tions <6 × 10 32 5 GRUZINOV 05 YUKA Solar System observations − <9.0 × 10 34 6 GERSHTEIN 04 From Ω value assuming RTG − tot >6 × 10 34 7 DVALI 03 Horizon scales − <8 × 10 20 8,9 FINN 02 DISP Binary pulsar orbital period de- crease 9,10 DAMOUR 91 Binary pulsar PSR 1913+16 − <7 × 10 23 TALMADGE 88 YUKA Solar system planetary astrometric data − − < 2 × 10 29 h 1 GOLDHABER 74 Rich clusters − 0 <7 × 10 28 HARE 73 Galaxy <8 × 104 HARE 73 2γ decay 1 CHOUDHURY 04 concludes from a study of weak-lensing data that masses heavier than about the inverse of 100 Mpc seem to be ruled out if the gravitation field has the Yukawa form.
  • Conformal Symmetry in Field Theory and in Quantum Gravity

    Conformal Symmetry in Field Theory and in Quantum Gravity

    universe Review Conformal Symmetry in Field Theory and in Quantum Gravity Lesław Rachwał Instituto de Física, Universidade de Brasília, Brasília DF 70910-900, Brazil; [email protected] Received: 29 August 2018; Accepted: 9 November 2018; Published: 15 November 2018 Abstract: Conformal symmetry always played an important role in field theory (both quantum and classical) and in gravity. We present construction of quantum conformal gravity and discuss its features regarding scattering amplitudes and quantum effective action. First, the long and complicated story of UV-divergences is recalled. With the development of UV-finite higher derivative (or non-local) gravitational theory, all problems with infinities and spacetime singularities might be completely solved. Moreover, the non-local quantum conformal theory reveals itself to be ghost-free, so the unitarity of the theory should be safe. After the construction of UV-finite theory, we focused on making it manifestly conformally invariant using the dilaton trick. We also argue that in this class of theories conformal anomaly can be taken to vanish by fine-tuning the couplings. As applications of this theory, the constraints of the conformal symmetry on the form of the effective action and on the scattering amplitudes are shown. We also remark about the preservation of the unitarity bound for scattering. Finally, the old model of conformal supergravity by Fradkin and Tseytlin is briefly presented. Keywords: quantum gravity; conformal gravity; quantum field theory; non-local gravity; super- renormalizable gravity; UV-finite gravity; conformal anomaly; scattering amplitudes; conformal symmetry; conformal supergravity 1. Introduction From the beginning of research on theories enjoying invariance under local spacetime-dependent transformations, conformal symmetry played a pivotal role—first introduced by Weyl related changes of meters to measure distances (and also due to relativity changes of periods of clocks to measure time intervals).
  • Weyl Gauge-Vector and Complex Dilaton Scalar for Conformal Symmetry and Its Breaking

    Weyl Gauge-Vector and Complex Dilaton Scalar for Conformal Symmetry and Its Breaking

    1 Weyl gauge-vector and complex dilaton scalar for conformal symmetry and its breaking Hans C. Ohanian1 Abstract Instead of the scalar “dilaton” field that is usually adopted to construct conformally invariant Lagrangians for gravitation, we here propose a hybrid construction, involving both a complex dilaton scalar and a Weyl gauge- vector, in accord with Weyl’s original concept of a non-Riemannian conformal geometry with a transport law for length and time intervals, for which this gauge vector is required. Such a hybrid construction permits us to avoid the wrong sign of the dilaton kinetic term (the ghost problem) that afflicts the usual construction. The introduction of a Weyl gauge-vector and its interaction with the dilaton also has the collateral benefit of providing an explicit mechanism for spontaneous breaking of the conformal symmetry, whereby the dilaton and the Weyl gauge-vector acquire masses somewhat smaller than mP by the Coleman-Weinberg mechanism. Conformal symmetry breaking is assumed to precede inflation, which occurs later by a separate GUT or electroweak symmetry breaking, as in inflationary models based on the Higgs boson. Keywords Quantum gravity • Conformal invariance • Spontaneous symmetry breaking •Weyl length transport Publication history First arXiv publication [v1] 30 January 2015. The final publication is available at Springer via http://dx.doi.org/10.1007/s10714-016-2023-8 and in General Relativity and Gravitation, March 2016, 48:25. 1 Introduction Modifications of Einstein’s gravitational theory that incorporate local conformal symmetry—that is, invariance 2 (x ) under the transformation g( x ) e g ( x ) , where ()x is an arbitrary real function—have been exploited in attempts at the solution of various of theoretical problems, such as renormalization of the stress tensor, renormalization of quantum gravity, quantum mechanics of black holes, analytic solutions and geodesic completeness in the early universe, and the dynamics that lead to inflation by symmetry breaking.
  • Conformally Invariant Equations for Graviton 50 5.1 the Conformally Invariant System of Conformal Degree 1

    Conformally Invariant Equations for Graviton 50 5.1 the Conformally Invariant System of Conformal Degree 1

    Conformally Invariant Equations for Graviton Mohsen Fathi Department of Physics, Tehran Central Branch Islamic Azad Univeristy arXiv:1210.3436v3 [physics.gen-ph] 12 Nov 2012 A thesis submitted for the Master degree Master of Science in Physics Tehran, Winter 2010 I am grateful to my supervisor Dr. Mohammad Reza Tanhayi for the helps, supports and scientific training, during this work and thereafter. Abstract Recent astrophysical data indicate that our universe might currently be in a de Sitter (dS) phase. The importance of dS space has been primarily ignited by the study of the inflationary model of the universe and the quantum gravity. As we know Einstein’s theory of gravitation (with a nonzero cosmological constant) can be interpreted as a theory of a metric field; that is, a symmetric tensor field of rank-2 on a fixed de Sitter back- ground. It has been shown the massless spin-2 Fierz-Pauli wave equation (or the linearized Einstein equation) is not conformally invariant. This result is in contrary with what we used to expect for massless theories. In this thesis we obtain conformally invariant wave equation for the massless spin-2 in the dS space. This study is motivated by the belief that confor- mal invariance may be the key to a future theory of quantum gravity. Contents Introduction 1 1 The Lorentz and the conformal groups, and the concept of invari- ance 3 1.1 Grouptheory ............................... 3 1.1.1 Orthogonalgroups ........................ 4 1.1.2 Rotationgroups.......................... 5 1.2 Invarianceunderagroupaction . 7 1.2.1 Invarianceofthelawsofphysics. 7 1.3 TheLorentzgroup ............................ 8 1.4 Theconformalgroup ..........................
  • Graviton J = 2

    Graviton J = 2

    Citation: P.A. Zyla et al. (Particle Data Group), Prog. Theor. Exp. Phys. 2020, 083C01 (2020) graviton J = 2 graviton MASS Van Dam and Veltman (VANDAM 70), Iwasaki (IWASAKI 70), and Za- kharov (ZAKHAROV 70) almost simultanously showed that “... there is a discrete difference between the theory with zero-mass and a theory with finite mass, no matter how small as compared to all external momenta.” The resolution of this ”vDVZ discontinuity” has to do with whether the linear approximation is valid. De Rham etal. (DE-RHAM 11) have shown that nonlinear effects not captured in their linear treatment can give rise to a screening mechanism, allowing for massive gravity theories. See also GOLDHABER 10 and DE-RHAM 17 and references therein. Experimental limits have been set based on a Yukawa potential or signal dispersion. h0 − − is the Hubble constant in units of 100 kms 1 Mpc 1. − The following conversions are useful: 1 eV = 1.783 × 10 33 g = 1.957 × −6 × −7 × 10 me ; λ¯C = (1.973 10 m) (1 eV/mg ). VALUE (eV) DOCUMENT ID TECN COMMENT − <6 × 10 32 1 CHOUDHURY 04 YUKA Weak gravitational lensing • • • We do not use the following data for averages, fits, limits, etc. • • • − <6.8 × 10 23 BERNUS 19 YUKA Planetary ephemeris INPOP17b − <1.4 × 10 29 2 DESAI 18 YUKA Gal cluster Abell 1689 − <5 × 10 30 3 GUPTA 18 YUKA SPT-SZ − <3 × 10 30 3 GUPTA 18 YUKA Planck all-sky SZ − <1.3 × 10 29 3 GUPTA 18 YUKA redMaPPer SDSS-DR8 − <6 × 10 30 4 RANA 18 YUKA Weak lensing in massive clusters − <8 × 10 30 5 RANA 18 YUKA SZ effect in massive clusters − <7 × 10 23 6 ABBOTT
  • Beyond the Cosmological Standard Model

    Beyond the Cosmological Standard Model

    Beyond the Cosmological Standard Model a;b; b; b; b; Austin Joyce, ∗ Bhuvnesh Jain, y Justin Khoury z and Mark Trodden x aEnrico Fermi Institute and Kavli Institute for Cosmological Physics University of Chicago, Chicago, IL 60637 bCenter for Particle Cosmology, Department of Physics and Astronomy University of Pennsylvania, Philadelphia, PA 19104 Abstract After a decade and a half of research motivated by the accelerating universe, theory and experi- ment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests. We begin by reviewing recent attempts to consistently modify Einstein gravity in the in- frared, focusing on the notion that additional degrees of freedom introduced by the modification must \screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second deriva- tives of the field are important. Examples of the first class, such as f(R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism.
  • Conformal Gravity Holography in Four Dimensions

    Conformal Gravity Holography in Four Dimensions

    Loyola University Chicago Loyola eCommons Physics: Faculty Publications and Other Works Faculty Publications 2014 Conformal Gravity Holography in Four Dimensions Daniel Grumiller Maria Irakleidou Iva Lovrekovic, Robert McNees Loyola University Chicago, [email protected] Follow this and additional works at: https://ecommons.luc.edu/physics_facpubs Part of the Physics Commons Recommended Citation Grumiller, D, M Irakleidou, I Lovrekovic, and R McNees. "Conformal Gravity Holography in Four Dimensions." Physical Review Letters 112, 2014. This Article is brought to you for free and open access by the Faculty Publications at Loyola eCommons. It has been accepted for inclusion in Physics: Faculty Publications and Other Works by an authorized administrator of Loyola eCommons. For more information, please contact [email protected]. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. © 2014 American Physical Society. week ending PRL 112, 111102 (2014) PHYSICAL REVIEW LETTERS 21 MARCH 2014 Conformal Gravity Holography in Four Dimensions † ‡ Daniel Grumiller,1,* Maria Irakleidou,1, Iva Lovrekovic,1, and Robert McNees2,§ 1Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrasse 8–10/136, A-1040 Vienna, Austria 2Department of Physics, Loyola University Chicago, Chicago, Illinois 60660, USA (Received 8 October 2013; published 18 March 2014) We formulate four-dimensional conformal gravity with (anti–)de Sitter boundary conditions that are weaker than Starobinsky boundary conditions, allowing for an asymptotically subleading Rindler term concurrent with a recent model for gravity at large distances. We prove the consistency of the variational principle and derive the holographic response functions. One of them is the conformal gravity version of the Brown–York stress tensor, the other is a “partially massless response”.
  • Rotating Black Holes in Conformal Gravity

    Rotating Black Holes in Conformal Gravity

    European Online Journal of Natural and Social Sciences 2014; www.european-science.com Vol.3, No.4 pp. 892-896 ISSN 1805-3602 Rotating black holes in conformal gravity Sara Dastan1*, Ali Farokhtabar1, Mohammad Ali Ganjali1,2, Bahare Hosseini1 1Department of Science, Faculty of Physics, Kharazmi University, Tehran, Iran 2Institute for Research in Fundamental Sciences(IPM), P.O. Box 19395-5531, Tehran, Iran *E-mail: [email protected] Received for publication: 02 June 2014. Accepted for publication: 30 September 2014. Abstract It is a long time since the motion of astronomical objects has been explained in the framework of Newtonian gravity. The great success of Newton’s law of universal gravitation in planetary motion persuaded astronomers to use this regime as a viable framework in the larger scales. Meanwhile, whenever a deviation of observed motions from expected ones were observed, the immediate question came up: should such anomalies be considered as incompleteness of laws of gravitation or as indication of the existence of unseen objects? In following we explain rotating black holes and solving this metric’s black hole with conformal gravity. Firstly explaining problem with DM then introducing conformal transformation and conformal gravity, in the last step we solve a metric for rotating black hole in the presence and absence of matter. Keywords: Rotation, Gravity, Black Holes, Conformal Gravity Introduction During the last century Einstein gravity (EG) was one the corner of theoretical physics. Despite of the success in explanation of various gravitational phenomena in nature, there are some unsolved basic problems such as singularity problem, black hole physics,… and most importantly quantum theory of gravity.
  • Curriculum Vitae Markus Amadeus Luty

    Curriculum Vitae Markus Amadeus Luty

    Curriculum Vitae Markus Amadeus Luty University of Maryland Department of Physics College Park, Maryland 20742 301-405-6018 e-mail: [email protected] Education Ph.D. in physics, University of Chicago, 1991 Honors B.S. in physics, B.S. in mathematics, University of Utah, 1987 Academic Honors Alfred P. Sloan Fellow (1997–1998) National Science Foundation Graduate Fellowship (1988–1991) Phi Beta Kappa, Phi Kappa Phi (1987) Kenneth Browning Memorial Scholarship (1986) National Merit Scholarship (1982–1986) Academic Positions 2001–present tenured associate professor, University of Maryland 1996–2001 assistant professor, University of Maryland 1994–1995 post-doctoral researcher, Massachusetts Institute of Technology 1991–1994 post-doctoral researcher, Lawrence Berkeley National Laboratory 1988–1991 graduate research assistant (with Y. Nambu), University of Chicago 1987–1988 graduate teaching assistant, University of Chicago 1985–1986 undergraduate teaching assistant, University of Utah 1 Recent Invited Conference/Workshop Talks • June 2003, SUSY 2003 (Tuscon) plenary talk: “Supersymmetry without Super- gravity.” • January 2003, PASCOS (Mumbai, India) plenary talk: “New ideas in super- symmetry breaking” • October 2002, Workshop on Frontiers Beyond the Standard Model (Mineapolis): “Supersymmetry without supergravity.” • August 2002, Santa Fe Workshop on Extra Dimensions and Beyond: “Super- symmetry without Supergravity.” • January 2002, ITP Brane World Workshop: “Anomaly Mediated Supersymme- try Breaking.” • April 2001, APS Division of Particles
  • Conformally Coupled General Relativity

    Conformally Coupled General Relativity

    universe Article Conformally Coupled General Relativity Andrej Arbuzov 1,* and Boris Latosh 2 ID 1 Bogoliubov Laboratory for Theoretical Physics, JINR, Dubna 141980, Russia 2 Dubna State University, Department of Fundamental Problems of Microworld Physics, Universitetskaya str. 19, Dubna 141982, Russia; [email protected] * Correspondence: [email protected] Received: 28 December 2017; Accepted: 7 February 2018; Published: 14 February 2018 Abstract: The gravity model developed in the series of papers (Arbuzov et al. 2009; 2010), (Pervushin et al. 2012) is revisited. The model is based on the Ogievetsky theorem, which specifies the structure of the general coordinate transformation group. The theorem is implemented in the context of the Noether theorem with the use of the nonlinear representation technique. The canonical quantization is performed with the use of reparametrization-invariant time and Arnowitt– Deser–Misner foliation techniques. Basic quantum features of the models are discussed. Mistakes appearing in the previous papers are corrected. Keywords: models of quantum gravity; spacetime symmetries; higher spin symmetry 1. Introduction General relativity forms our understanding of spacetime. It is verified by the Solar System and cosmological tests [1,2]. The recent discovery of gravitational waves provided further evidence supporting the theory’s viability in the classical regime [3–6]. Despite these successes, there are reasons to believe that general relativity is unable to provide an adequate description of gravitational phenomena in the high energy regime and should be either modified or replaced by a new theory of gravity [7–11]. One of the main issues is the phenomenon of inflation. It appears that an inflationary phase of expansion is necessary for a self-consistent cosmological model [12–14].
  • Classical and Quantum Consistency of the DGP Model

    Classical and Quantum Consistency of the DGP Model

    IFT-UAM/CSIC-04-13 CERN-PH-TH/2004-063 Classical and Quantum Consistency of the DGP Model Alberto Nicolis a and Riccardo Rattazzi b aInstituto de F´ısica Te´orica, C–XVI, UAM, 28049 Madrid, Spain bPhysics Department, Theory Division, CERN, CH–1211 Geneva 23, Switzerland Abstract We study the Dvali-Gabadadze-Porrati model by the method of the boundary effective action. The truncation of this action to the bending mode π consistently describes physics in a wide range of regimes both at the classical and at the quantum level. The Vainshtein effect, which restores agreement with precise tests of general relativity, follows straightforwardly. We give a simple and general proof of stability, i.e. absence of ghosts in the fluctuations, valid for most of the relevant cases, like for instance the spherical source in asymptotically flat space. However we confirm that around certain interesting self-accelerating cosmological solutions there is a ghost. We consider the issue of quantum corrections. Around flat space π becomes strongly coupled below a macroscopic length of 1000 km, thus impairing the predictivity of the model. Indeed the tower of higher dimensional operators which is expected by a generic UV completion of the model limits predictivity at even larger length scales. We outline a non-generic but consistent choice of counterterms for which this disaster does not happen and for which the model remains calculable and successful in all the astrophysical situations of interest. By this choice, the extrinsic curvature Kµν acts roughly like a dilaton field controlling the strength of the interaction and the cut-off scale at each space-time point.
  • Gravitational Waves in Massive Conformal Gravity Arxiv:2007.03637V2 [Gr-Qc] 23 Jul 2020

    Gravitational Waves in Massive Conformal Gravity Arxiv:2007.03637V2 [Gr-Qc] 23 Jul 2020

    Gravitational waves in massive conformal gravity F. F. Faria ∗ Centro de Ci^enciasda Natureza, Universidade Estadual do Piau´ı, 64002-150 Teresina, PI, Brazil Abstract First, we obtain the plane wave solution of the linearized massive conformal gravity field equations. It is shown that the theory has seven physical plane waves. In addition, we investigate the gravitational radiation from binary systems in massive conformal gravity. We find that the theory with large graviton mass can reproduce the orbit of binaries by the emission of gravitational waves. arXiv:2007.03637v2 [gr-qc] 23 Jul 2020 PACS numbers: 04.50.Kd, 04.30.-w * [email protected] 1 Introduction Over the years several alternative theories of gravity have emerged in the attempt to solve some of the problems presented by the general theory of rel- ativity, such as the dark matter and dark energy problems. Besides solving these problems, for an alternative theory of gravity to be considered consis- tent, it must also reproduce the successful predictions of general relativity. One of these recently confirmed predictions is the existence of gravitational waves [1, 2, 3, 4]. Among the many alternative theories of gravity that have already studied the gravitational waves phenomenology is conformal gravity (CG). It was shown that the plane wave of this theory is composed of the usual plane wave of general relativity plus a plane wave that grows linearly in time [5], which causes the energy carried by the CG plane wave to diverges in momentum space [6]. In this paper, we intend to study the behavior of gravitational waves in another alternative theory of gravity with conformal symmetry called massive conformal gravity (MCG) [7].