Lattice Field Theory Study of Magnetic Catalysis in Graphene
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Geometric Lattice Models and Irrational Conformal Field Theories Romain Couvreur
Geometric lattice models and irrational conformal field theories Romain Couvreur To cite this version: Romain Couvreur. Geometric lattice models and irrational conformal field theories. Mathematical Physics [math-ph]. Sorbonne Université, 2019. English. NNT : 2019SORUS062. tel-02569051v2 HAL Id: tel-02569051 https://hal.archives-ouvertes.fr/tel-02569051v2 Submitted on 21 Oct 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THÈSE DE DOCTORAT DE L’UNIVERSITÉ PIERRE ET MARIE CURIE Spécialité : Physique École doctorale no564: Physique en Île-de-France réalisée au Laboratoire de Physique Théorique - ENS et à l’Institut de Physique Théorique - CEA sous la direction de Jesper Jacobsen et Hubert Saleur présentée par Romain Couvreur pour obtenir le grade de : DOCTEUR DE L’UNIVERSITÉ PIERRE ET MARIE CURIE Sujet de la thèse : Geometric lattice models and irrational conformal field theories soutenue le 25 juin 2019 devant le jury composé de : M. Paul Fendley Rapporteur M. Ilya Gruzberg Rapporteur M. Jean-Bernard Zuber Examinateur Mme Olalla Castro-Alvaredo Examinatrice M. Benoit Estienne Examinateur M. Jesper Lykke Jacobsen Directeur de thèse M. Hubert Saleur Membre invité (co-directeur) Geometric lattice models and irrational conformal field theories Abstract: In this thesis we study several aspects of two-dimensional lattice models of statistical physics with non-unitary features. -
Condensed Matter Physics with Light and Atoms: Strongly Correlated Cold Fermions in Optical Lattices
Condensed Matter Physics With Light And Atoms: Strongly Correlated Cold Fermions in Optical Lattices. Antoine Georges Centre de Physique Th´eorique, Ecole Polytechnique, 91128 Palaiseau Cedex, France Lectures given at the Enrico Fermi Summer School on ”Ultracold Fermi Gases” organized by M. Inguscio, W. Ketterle and C. Salomon (Varenna, Italy, June 2006) Summary. — Various topics at the interface between condensed matter physics and the physics of ultra-cold fermionic atoms in optical lattices are discussed. The lec- tures start with basic considerations on energy scales, and on the regimes in which a description by an effective Hubbard model is valid. Qualitative ideas about the Mott transition are then presented, both for bosons and fermions, as well as mean-field theories of this phenomenon. Antiferromagnetism of the fermionic Hubbard model at half-filling is briefly reviewed. The possibility that interaction effects facilitate adiabatic cooling is discussed, and the importance of using entropy as a thermometer is emphasized. Geometrical frustration of the lattice, by suppressing spin long-range order, helps revealing genuine Mott physics and exploring unconventional quantum magnetism. The importance of measurement techniques to probe quasiparticle ex- arXiv:cond-mat/0702122v1 [cond-mat.str-el] 5 Feb 2007 citations in cold fermionic systems is emphasized, and a recent proposal based on stimulated Raman scattering briefly reviewed. The unconventional nature of these excitations in cuprate superconductors is emphasized. c Societ`aItaliana di Fisica 1 2 A. Georges 1. – Introduction: a novel condensed matter physics. The remarkable recent advances in handling ultra-cold atomic gases have given birth to a new field: condensed matter physics with light and atoms. -
Low-Dimensional Chiral Physics: Gross-Neveu Universality and Magnetic Catalysis
Low-Dimensional Chiral Physics: Gross-Neveu Universality and Magnetic Catalysis Dissertation zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat) vorgelegt dem Rat der Physikalisch-Astronomischen Fakult¨at der Friedrich-Schiller-Universit¨at Jena von Dipl.-Phys. Daniel David Scherer geboren am 19. Dezember 1982 in N¨urnberg Gutachter: 1. Prof. Dr. Holger Gies, Friedrisch-Schiller-Universit¨at Jena 2. Prof. Dr. Christian Fischer, Justus-Liebig-Universit¨at Gießen 3. Jun. Prof. Dr. Lorenz Bartosch, Goethe-Universit¨at Frankfurt Tag der Disputation: 27. September 2012 Niedrigdimensionale Chirale Physik: Gross-Neveu-Universalit¨atund magnetische Katalyse Zusammenfassung In der vorliegenden Dissertation wird das 3-dimensionale, chiral symmetrische Gross-Neveu Mo- dell untersucht. Diese niedrigdimensionale Quantenfeldtheorie beschreibt den Kontinuumslimes des Niedrigenergiesektors bestimmter auf dem Gitter realisierter Modelle. Die funktionale Renormierungsgruppe erlaubt es, auf nichtperturbative Art und Weise die physi- kalischen Eigenschaften quantenmechanischer Vielteilchensysteme und Quantenfeldtheorien zu stu- dieren. Den Startpunkt hierf¨ur stellt eine auf 1-Schleifen Niveau formal exakte Flussgleichung f¨ur das erzeugende Funktional der 1-Teilchen irreduziblen Vertexfunktionen dar. Im Rahmen einer Gradientenentwicklung - ideal f¨ur die Bestimmung der Infrarotasymptotik der impuls- und fre- quenzabh¨angigen Vertizes der Theorie – untersuchen wir das Regime starker Kopplung ¨uber den formalen Limes unendlicher Flavorzahlen hinaus. Dieses Regime wird durch einen entsprechenden Fixpunkt kontrolliert, der gleichzeitig eine kritische Mannigfaltigkeit definiert, welche wiederum eine Phase masseloser von einer Phase massiver Dirac-Fermionen trennt. Der zugeh¨orige Quanten- phasen¨ubergang ist von 2. Ordnung. Nach einer ersten Analyse der Theorie in rein fermionischer Formulierung wird vermittels einer Hubbard-Stratonovich-Transformation zu einer partiell boson- isierten Beschreibung ¨ubergegangen. -
Arxiv:1707.05600V3 [Hep-Lat] 5 Mar 2018
Meson masses in electromagnetic fields with Wilson fermions G. S. Bali,1, 2, ∗ B. B. Brandt,3, † G. Endr}odi,3, ‡ and B. Gl¨aßle1, § 1Institute for Theoretical Physics, Universit¨atRegensburg, D-93040 Regensburg, Germany. 2Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India. 3Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany We determine the light meson spectrum in QCD in the presence of background magnetic fields using quenched Wilson fermions. Our continuum extrapolated results indicate a monotonous reduc- tion of the connected neutral pion mass as the magnetic field grows. The vector meson mass is found to remain nonzero, a finding relevant for the conjectured ρ-meson condensation at strong magnetic fields. The continuum extrapolation was facilitated by adding a novel magnetic field-dependent improvement term to the additive quark mass renormalization. Without this term, sizable lattice artifacts that would deceptively indicate an unphysical rise of the connected neutral pion mass for strong magnetic fields are present. We also investigate the impact of these lattice artifacts on further observables like magnetic polarizabilities and discuss the magnetic field-induced mixing between ρ- mesons and pions. We also derive Ward-Takashi identities for QCD+QED both in the continuum formulation and for (order a-improved) Wilson fermions. PACS numbers: 11.15.Ha,11.40.Ha,12.38.Aw,14.40.Be I. INTRODUCTION Background magnetic fields have a decisive impact on the physics of quarks and gluons and offer a wide range of applications. Strong magnetic fields appear in noncentral heavy-ion collisions [1, 2], inside magnetars [3], and might have been generated during the evolution of the early Universe [4]. -
Lattice Vibration As a Knob for Novel Quantum Criticality: Emergence Of
Lattice vibration as a knob for novel quantum criticality : Emergence of supersymmetry from spin-lattice coupling SangEun Han,1, ∗ Junhyun Lee,2, ∗ and Eun-Gook Moon1, y 1Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea 2Department of Physics, Condensed Matter Theory Center and the Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA (Dated: November 6, 2019) Control of quantum coherence in many-body system is one of the key issues in modern condensed matter. Conventional wisdom is that lattice vibration is an innate source of decoherence, and amounts of research have been conducted to eliminate lattice effects. Challenging this wisdom, here we show that lattice vibration may not be a decoherence source but an impetus of a novel coherent quantum many-body state. We demonstrate the possibility by studying the transverse-field Ising model on a chain with renormalization group and density-matrix renormalization group method, and theoretically discover a stable N = 1 supersymmetric quantum criticality with central charge c = 3=2. Thus, we propose an Ising spin chain with strong spin-lattice coupling as a candidate to observe supersymmetry. Generic precursor conditions of novel quantum criticality are obtained by generalizing the Larkin-Pikin criterion of thermal transitions. Our work provides a new perspective that lattice vibration may be a knob for exotic quantum many-body states. Quantum states on a lattice inevitably couple to lattice vibration, and the coupling is known to be one of the hxˆ main sources of decoherence of quantum states. To be ~si+1 z specific, let us consider a spin system on a lattice whose z s i+1 i Hamiltonian may be schematically written by, ~si -Js 0 0 H = Hspin + Hphonon + gHs−l; i+1 2 u 0 γ 0 where Hspin=phonon is for a pure spin/phonon system, and Mω Hs−l is for the spin-lattice coupling. -
Chiral Symmetry Breaking and Restoration in 2+1 Dimensions From
PHYSICAL REVIEW D 98, 106007 (2018) Chiral symmetry breaking and restoration in 2 + 1 dimensions from holography: Magnetic and inverse magnetic catalysis † ‡ Diego M. Rodrigues,1,* Danning Li,2, Eduardo Folco Capossoli,1,3, and Henrique Boschi-Filho1,§ 1Instituto de Física, Universidade Federal do Rio de Janeiro, 21.941-972, Rio de Janeiro RJ, Brazil 2Department of Physics and Siyuan Laboratory, Jinan University, Guangzhou 510632, China 3Departamento de Física and Mestrado Profissional em Práticas da Educação Básica (MPPEB), Col´egio Pedro II, 20.921-903, Rio de Janeiro RJ, Brazil (Received 3 August 2018; published 9 November 2018) We study the chiral symmetry breaking and restoration in (2 þ 1)-dimensional gauge theories from the holographic hardwall and softwall models. We describe the behavior of the chiral condensate in the presence of an external magnetic field for both models at finite temperature. For the hardwall model we find magnetic catalysis (MC) in different setups. For the softwall model we find inverse magnetic catalysis (IMC) and MC in different situations. We also find for the softwall model a crossover transition from IMC to MC at a pseudocritical magnetic field. This study also shows spontaneous symmetry breaking for both models. Interestingly, for B ¼ 0 in the softwall model, we found a nontrivial expectation value for the chiral condensate. DOI: 10.1103/PhysRevD.98.106007 I. INTRODUCTION in order to reproduce the nonperturbative physics of QCD, one must break the conformal invariance in the Much theoretical progress on the nonperturbative phys- original AdS=CFT correspondence. There are two well- ics of relativistic quantum field theories (RQFT) has been known models which do this symmetry breaking: the achieved recently. -
CDT Quantum Toroidal Spacetimes: an Overview
universe Review CDT Quantum Toroidal Spacetimes: An Overview Jan Ambjorn 1,2,* , Zbigniew Drogosz 3 , Jakub Gizbert-Studnicki 3, Andrzej Görlich 3, Jerzy Jurkiewicz 3 and Dániel Nèmeth 3 1 The Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark 2 Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands 3 Institute of Theoretical Physics, Jagiellonian University, Łojasiewicza 11, PL 30-348 Kraków, Poland; [email protected] (Z.D.); [email protected] (J.G.-S.); [email protected] (A.G.); [email protected] (J.J.); [email protected] (D.N.) * Correspondence: [email protected] Abstract: Lattice formulations of gravity can be used to study non-perturbative aspects of quantum gravity. Causal Dynamical Triangulations (CDT) is a lattice model of gravity that has been used in this way. It has a built-in time foliation but is coordinate-independent in the spatial directions. The higher-order phase transitions observed in the model may be used to define a continuum limit of the lattice theory. Some aspects of the transitions are better studied when the topology of space is toroidal rather than spherical. In addition, a toroidal spatial topology allows us to understand more easily the nature of typical quantum fluctuations of the geometry. In particular, this topology makes it possible to use massless scalar fields that are solutions to Laplace’s equation with special boundary conditions as coordinates that capture the fractal structure of the quantum geometry. -
Quantum Computing for QCD?
Quantum Computing for QCD? Yannick Meurice The University of Iowa [email protected] With Alexei Bazavov, Sam Foreman, Erik Gustafson, Yuzhi Liu, Philipp Preiss, Shan-Wen Tsai, Judah Unmuth-Yockey, Li-Ping Yang, Johannes Zeiher, and Jin Zhang Supported by the Department of Energy USQCD, BNL, 4/27/19 Yannick Meurice (U. of Iowa) Quantum Computing for QCD? USQCD, BNL, 4/27/19 1 / 56 Content of the talk Quantum Computing (QC) for QCD: what do we want to do? Strategy: big goals with enough intermediate steps explore as many paths as possible leave room for serendipity Tensor tools: QC friends and competitors (RG) Quantum simulations experiments (analog): cold atoms, ions ... Quantum computations (digital): IBM, IonQ, Rigetti, ... Abelian Higgs model with cold atom ladders Benchmark for real time scattering (arXiv:1901.05944, PRD in press with Erik Gustafson and Judah Unmuth-Yockey) Symmetry preserving truncations (YM, arxiv:1903.01918) Quantum Joule experiments (arXiv:1903.01414, with Jin Zhang and Shan-Wen Tsai) Pitch for a quantum center for theoretical physics (HEP, NP, ...) Conclusions Yannick Meurice (U. of Iowa) Quantum Computing for QCD? USQCD, BNL, 4/27/19 2 / 56 Computing with quantum devices (Feynman 82)? The number of transistors on a chip doubled almost every two years for more than 30 years At some point, the miniaturization involves quantum mechanics Capacitors are smaller but they are still on (charged) or off (uncharged) Figure: Moore’s law, source: qubits: jΨi = αj0i + βj1i is a Wikipedia superposition of the two possibilities. Can we use quantum devices to explore large Hilbert spaces? Yes, if the interactions are localized (generalization of Trotter product Figure: Quantum circuit for the formula, Lloyd 96) quantum Ising model (E. -
Solitons in Lattice Field Theories Via Tight-Binding Supersymmetry
Solitons in lattice field theories via tight-binding supersymmetry Shankar Balasubramanian,a Abu Patoary,b;c and Victor Galitskib;c aCenter for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA bJoint Quantum Institute, University of Maryland, College Park, MD 20742, USA cCondensed Matter Theory Center, Department of Physics, University of Maryland, College Park, MD 20742, USA Abstract: Reflectionless potentials play an important role in constructing exact solutions to classical dynamical systems (such as the Korteweg–de Vries equation), non-perturbative solutions of various large-N field theories (such as the Gross-Neveu model), and closely related solitonic solutions to the Bogoliubov-de Gennes equations in the theory of superconductivity. These solutions rely on the inverse scattering method, which reduces these seemingly unrelated problems to identifying reflectionless potentials of an auxiliary one-dimensional quantum scattering problem. There are several ways of constructing these potentials, one of which is quantum mechanical supersymmetry (SUSY). In this paper, motivated by recent experimental platforms, we generalize this framework to develop a theory of lattice solitons. We first briefly review the classic inverse scattering method in the continuum limit, focusing on the Korteweg–de Vries (KdV) equation and SU(N) Gross-Neveu model in the large N limit. We then generalize this methodology to lattice versions of interacting field theories. Our analysis hinges on the use of trace identities, which are relations connecting the potential of an equation of motion to the scattering data. For a discrete Schrödinger operator, such trace identities had been known as far back as Toda; however, we derive a new set of identities for the discrete Dirac operator. -
Arxiv:1004.3396V4 [Cond-Mat.Mes-Hall]
Electronic Properties of Graphene in a Strong Magnetic Field M. O. Goerbig 1Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS UMR 8502, F-91405 Orsay, France (Dated: November 24, 2011) We review the basic aspects of electrons in graphene (two-dimensional graphite) exposed to a strong perpendicular magnetic field. One of its most salient features is the relativistic quan- tum Hall effect the observation of which has been the experimental breakthrough in identifying pseudo-relativistic massless charge carriers as the low-energy excitations in graphene. The effect may be understood in terms of Landau quantisation for massless Dirac fermions, which is also the theoretical basis for the understanding of more involved phenomena due to electronic interactions. We present the role of electron-electron interactions both in the weak-coupling limit, where the electron-hole excitations are determined by collective modes, and in the strong-coupling regime of partially filled relativistic Landau levels. In the latter limit, exotic ferromagnetic phases and incompressible quantum liquids are expected to be at the origin of recently observed (fractional) quantum Hall states. Furthermore, we discuss briefly the electron-phonon coupling in a strong magnetic field. Although the present review has a dominating theoretical character, a close con- nection with available experimental observation is intended. PACS numbers: 81.05.ue, 73.43.Lp, 73.22.Pr Contents IV. Magneto-Phonon Resonance in Graphene 31 A. Electron-Phonon Coupling 31 I. Introduction to Graphene 1 1. Coupling Hamiltonian 32 A. The Carbon Atom and its Hybridizations 2 2. Hamiltonian in terms of magneto-exciton operators 32 B. -
Computational Physics Extended Lattice
CONTENTS - Continued PHYSICAL REVIEW E THIRD SERIES, VOLUME 95, NUMBER 5 MAY 2017 Computational Physics Extended lattice Boltzmann scheme for droplet combustion (15 pages) ..................................... 053301 Mostafa Ashna, Mohammad Hassan Rahimian, and Abbas Fakhari Macroscopically constrained Wang-Landau method for systems with multiple order parameters and its application to drawing complex phase diagrams (14 pages) ......................................... 053302 C. H. Chan, G. Brown, and P. A. Rikvold Grain coarsening in two-dimensional phase-field models with an orientation field (12 pages) .................. 053303 Bálint Korbuly, Tamás Pusztai, Hervé Henry, Mathis Plapp, Markus Apel, and László Gránásy Towards a unified lattice kinetic scheme for relativistic hydrodynamics (14 pages) ........................... 053304 A. Gabbana, M. Mendoza, S. Succi, and R. Tripiccione Surprising convergence of the Monte Carlo renormalization group for the three-dimensional Ising model (6 pages) 053305 Dorit Ron, Achi Brandt, and Robert H. Swendsen Evaluating the morphological completeness of a training image (11 pages) .................................. 053306 Mingliang Gao, Qizhi Teng, Xiaohai He, Junxi Feng, and Xue Han Implementation of dual time-stepping strategy of the gas-kinetic scheme for unsteady flow simulations (13 pages) 053307 Ji Li, Chengwen Zhong, Yong Wang, and Congshan Zhuo Multidimensional Chebyshev interpolation for warm and hot dense matter (10 pages) ........................ 053308 Gérald Faussurier and Christophe Blancard + Numerical solution of the time-dependent Schrödinger equation for H2 ion with application to high-harmonic generation and above-threshold ionization (8 pages) ..................................................... 053309 B. Fetic´ and D. B. Miloševic´ The editors and referees of PRE find these papers to be of particular interest, importance, or clarity. Please see our Announcement Phys. Rev. E 89, 010001 (2014). -
Phase Transitions of Lattice Models (Rennes Lectures)
PHASE TRANSITIONS OF LATTICE MODELS (RENNES LECTURES) Roman Kotecky´ Charles University, Prague and CPT CNRS, Marseille Summary I. Introduction. Notion of phase transitions (physics) → Ising model → first order and continuous phase transitions. II. Gibbs states. Phase transitions as instabilities with respect to boundary conditions. III. A closer look on Ising model. III.1. High temperatures. Almost independent random variables. Intermezzo: cluster expansions. III.2. Low temperatures. Almost independent random contours — Peierls argument. IV. Asymmetric models. IV.1. Perturbed Ising model. (As a representant of a general case.) IV.2. Potts model. V. Phasediagram — Pirogov-Sinai theory. V.1. Recovering essential independence. V.2. Use of a symmetry. (If possible.) V.3. General case. V.4. Completeness of the phase diagram. VI. Topics for which there is no place here. Degeneracy (Potts antiferromagnet, ANNNI), disorder (random fields, Imry-Ma argu- ment), interfaces (translation-noninvariant Gibbs states, roughening, equilibrium crys- tal shapes), finite size effects. Typeset by AMS-TEX 1 2 R.Kotecky´ I. Introduction My goal in these lectures is to try to explain in a consistent way a piece of machinery used to study phase transitions of lattice models. Techniques I have in mind here can be characterized as those that are stable with respect to small perturbations. In particular, no symmetries or particular restrictions on monotonicity or sign of interactions should play a role. The main tool is a geometric characterization of phases and a study of the probability distributions of underlying geometric objects. I will try to restrict myself to simplest possible cases bearing some general features. When physicists talk about phase transitions they have in mind some discontinuity (or at least nonanalyticity) of thermodynamic functions describing the state of the system (say, the density for the liquid-gas transition) as function of external parameters (temperature, pressure ...).