Aspects of Lorentz and CPT Violation in Cosmology
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NATIONAL CENTRE FOR NUCLEAR RESEARCH DOCTORAL THESIS Aspects of Lorentz and CPT Violation in Cosmology Author: Supervisor: Nils Albin NILSSON Prof. Dr Hab. Mariusz P. DA¸BROWSKI A thesis submitted in fulfillment of the requirements for the degree of Doctor of Physical Sciences at the National Centre for Nuclear Research March 10, 2020 iii Declaration of Authorship I, Nils Albin NILSSON, declare that this thesis titled, “Aspects of Lorentz and CPT Violation in Cosmology” and the work presented in it are my own. I confirm that: • This work was done wholly or mainly while in candidature for a research de- gree at the National Centre for Nuclear Research. • Where any part of this thesis has previously been submitted for a degree or any other qualification at the National Centre for Nuclear Research or any other institution, this has been clearly stated. • Where I have consulted the published work of others, this is always clearly attributed. • Where I have quoted from the work of others, the source is always given. With the exception of such quotations, this thesis is entirely my own work. • I have acknowledged all main sources of help. • Where the thesis is based on work done by myself jointly with others, I have made clear exactly what was done by others and what I have contributed my- self. Signed: Date: v “Nature never deceives us; it is always we who deceive ourselves” Jean-Jaques Rousseau vii NATIONAL CENTRE FOR NUCLEAR RESEARCH Abstract National Centre for Nuclear Research Doctor of Physical Sciences Aspects of Lorentz and CPT Violation in Cosmology by Nils Albin NILSSON The breaking of Lorentz symmetry can give rise to a wealth of observational con- sequences. The main topic of this thesis is to explore models of gravitation and cosmology with Lorentz symmetry violation (closely linked to Charge-Parity-Time (CPT) violation). Five Lorentz-violating models or frameworks are outlined in this thesis, and three of these are subsequently chosen and studied in the following chap- ters. Doubly General Relativity breaks Lorentz symmetry through a modification of the dispersion relation of particles. This is combined with the kinematic modified dispersion relations common in phenomenological studies of Lorentz violation with high-energy gamma rays. By applying a large cosmological dataset to the result- ing model, it is found that the lower limit on the energy scale of Lorentz violation is 16 ELV ∼ 10 GeV (1s). Hoˇrava-Lifshitzgravity is a possibly UV-complete quantum- gravity theory candidate. By again applying a large updated cosmological dataset new constraints on the cosmological parameters are found. In particular, the curva- −3 ture density parameter Wk found to be non-zero (−3.30 ± 0.20) × 10 (1s). More- over, this model is discussed in context of the Hubble parameter tension, through which the Hoˇrava-Lifshitzcoupling parameter lis given new contraints. It is found that Lorentz violation can contribute up to 38% of the Hubble tension. The Standard- Model Extension is a general, theory-agnostic framework for testing Lorentz and CPT violation. Here, the Hamiltonian formulation of the Standard-Model Extension gravitational sector is presented. viii Polski: Łamanie symetrii Lorentza moze˙ prowadzi´cdo wielu konsekwencji obserwacyjnych. Głównym tematem rozprawy jest zbadanie modeli grawitacyjnych i kosmologicznych, w których zachodzi scenariusz naruszenia tej symetrii (blisko spokrewnione ze zła- maniem symetrii CPT – Ładunku, Parzysto´sci,Czasu). W pracy opisano pi˛e´cróznych˙ modeli ze scenariuszem łamania symetrii Lorentza, z czego trzy s ˛awybrane do dal- szej analizy w kolejnych rozdziałach. Podwójna Ogólna Teoria Wzgl˛edno´sci(Dou- bly General Relativity) łamie symetri˛eLorentza poprzez modyfikacj˛erelacji dysper- syjnych cz ˛astek.Powyzszy˙ model jest poł ˛aczonyz kinematycznie zmodyfikowanymi relacjami dyspersyjnymi powszechnymi w badaniach fenomenologicznych łamania symetrii Lorentza za pomoc ˛awysokoenergetycznych promieni gamma. Porównu- j ˛acuzyskany model z szerokim zestawem danych kosmologicznych stwierdzono, 16 ze˙ dolna granica skali energii łami ˛acejsymetri˛eLorentza wynosi ELV ∼ 10 GeV (1s). Teoria grawitacji Hoˇravy-Lifszyca jest potencjalnym kandydatem na kom- pletn ˛aw ultrafiolecie teori˛ekwantowej grawitacji. Ponownie, poprzez zastosowanie wielkich zestawów danych kosmologicznych do tego modelu, udało si˛ewyznaczy´c nowe ograniczenia na warto´scijego parametrów kosmologicznych. W szczegól- no´scistwierdzono, ze˙ krzywizna przestrzeni jest niezerowa (−3, 30 ± 0, 20) × 10−3 (1s). Co wi˛ecej,model ten jest omawiany w kontek´scierozbiezno´scidotycz˙ ˛acych parametru Hubble’a (Hubble parameter tension), w wyniku czego otrzymuje si˛e nowe ograniczenia na warto´s´cparametru l w teorii Hoˇravy-Lifszyca.Stwierdzono, ze˙ scenariusz łamania symetrii Lorentza moze˙ przyczyni´csi˛ew 38% do rozwi ˛aza- nia problemu rozbiezno´sciparametru˙ Hubble’a. Rozszerzony Model Standardowy jest ogóln ˛a,efektywn ˛ateori ˛apola mog ˛ac˛aposłuzy´cdo˙ testowania scenariuszy ła- mania symetrii Lorentza. W rozprawie, zaprezentowane jest Hamiltonowskie sfor- mułowanie sektora grawitacyjnego dla Rozszerzonego Modelu Standardowego. ix Svenska: Lorentzbrott kan ge upphov till mängder av observerbara konsekvenser. Denna avhandlings huvudtema är att utforska gravitations- och kosmologimodeller som inkluderar Lorentzbrott (kopplat till Laddning-Paritet-Tidbrott (CPT)). Fem Lorentzbry- tande modeller och ramverk skissas i början av denna avhandling och tre av dessa väljs sedermera ut och studeras i efterföljande kapitel. Dubbelt Allmän Relativitet- steori (Doubly General Relativity) bryter Lorentzsymmetri genom att modifiera dis- persionsrelationen för partiklar. Detta kombineras med de kinematiskt modifierade dispersionsrelationerna som är vanliga i fenomenologiska studier av högenergifo- toner. Genom att applicera ett stort kosmologiskt dataset på den resulterande kos- mologiska modellen bestämdes det lägre värdet för den karakteristiska energiskalan 16 för Lorentzbrott till ELV ∼ 10 GeV (1s). Hoˇrava-Lifshitzgravitationär en möjli- gen UV-komplett kvantgravitationskandidat. Genom att återigen applicera ett stort uppdaterat kosmologiskt dataset bestäms nya värden på de kosmologiska parame- trarna. I synnerhet kan den spatiala kurvaturen bestämmas till (−3.30 ± 0.20) × 10−3 (1s). Hubblespänningen (Hubble tension) diskuteras också inom denna mod- ell som en effekt av föredragna referensramar (preferred-frame effects), och värden på Hoˇrava-Lifshitzparametrarbestäms från Hubblespänningsdata. Det fastställs också att Lorentzbrott kan bidra med upp till 38% av Hubblespänningen. Stan- dardmodellutvidgningen (Standard-Model Extension) är ett allmännt ramverk för att parametrisera och testa Lorentz- och CPT-brott. Här härleds och presenteras Hamiltonformuleringen av Standardmodellutvidgningens gravitationssektor. xi Acknowledgements The writing of this thesis would not have been possible without the support and guidance of my supervisor, Mariusz P. Da¸browski, who gave me a lot of research freedom and encouraged me to be independent. His influence has made me the researcher who I am today and has helped shape this thesis into what is printed within these pages. To Ewa Czuchry, who took me in when all I had was an idea and encouraged me to tackle hard problems. To Vincenzo Salzano who taught me about MCMC and patiently answered my endless questions. To Quentin Bailey and Kellie O’Neal-Ault who helped open the door to an exciting field and for helping me develop a long-term collaboration, and to all the people at Embry-Riddle for treating me like one of their own from day one. To Artur and Viktor, with whom I could always discuss ideas, and to Harrison for proofreading parts of this thesis. To my parents, who supported me even when it brought me far from home, and to Sarah, for her unwaivering support. Special thanks goes to the National Centre for Nuclear Research and National Science Center. Their financial support made it possible for me to attend confer- ences and visit scientists in Poland, Germany, Italy, Greece, Portugal, Canada, and the USA. I also thank the National Centre for Nuclear Research for the use of the CIS´ high-performance computing cluster. To all the people who have helped me along the way, thank you. xiii Contents Declaration of Authorship iii Abstract vii Acknowledgements xi 1 Introduction1 1.1 Research Aims and Scope..........................5 1.2 Linkage of Scientific Papers.........................6 2 The Role of Lorentz and CPT Symmetry in Modern Physics7 2.1 Explicit versus Spontaneous Lorentz Symmetry Breaking........8 2.2 CPT Symmetry in an Expanding Universe................. 10 2.3 General Properties of Models with Lorentz Violation........... 11 2.4 Common Lorentz-Violating Models and Frameworks.......... 12 2.4.1 Doubly General Relativity...................... 12 2.4.2 Hoˇrava-LifshitzGravity....................... 15 2.4.3 Einstein-Aether Theory....................... 17 2.4.4 Bumblebee Gravity.......................... 18 2.4.5 The Standard-Model Extension................... 20 3 Modified Dispersion Relations in Gravity; Doubly General Relativity 23 3.1 Lorentz Invariance Violation in Rainbow Gravity............. 25 3.1.1 Lorentz Invariance Violation.................... 25 3.1.2 Simple Lorentz Invariance Violating Cosmological Framework 26 3.1.3 Two specific choices of the scaling function h±(E) ........ 29 3.1.4 Comparison with the LCDM model................ 30 3.2 Discussion and Conclusions......................... 32 xiv