Blar i NTNU Open på forfatter "Andersen, Jens Oluf"
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Linearized general relativity and its quantization
Pedersen, Alf-Håkon (Master thesis, 2017)We begin by deriving the Einstein equation from the Einstein-Hilbert action integral using variational methods; Variation with respect to the metric and the Palatini variation. The vacuum solution (Schwarzschild solution) ... -
N=4 supersymmetric Yang-Mills thermodynamics from effective field theory
Andersen, Jens Oluf; strickland, Michael; Tantary, Ubaid; Du, Qianqian (Peer reviewed; Journal article, 2022)The free energy density of N ¼ 4 supersymmetric Yang-Mills theory in four space-time dimensions is derived through second order in the ’t Hooft coupling λ at finite temperature using effective-field theory methods. The ... -
Neutron and Quark Stars
Sæther, Halvor (Master thesis, 2020)I denne masteroppgaven tar vi for oss mange av hovedtrekkene knyttet til det å bestemme strukturen og den øvre massegrensen til kompakte stjerner, spesielt nøytronstjerner og kvarkstjerner. Vi begynner med en innføring i ... -
Neutron stars - Investigating candidates for the equation of state in the relativistic mean-field approximation
Sivertsen, Lars (Master thesis, 2018)Various models for the equation of state (EoS) for a neutron star have been considered using the relativistic mean-field approximation. Firstly, we derive Einstein's field equations and apply them to a spherically symmetric ... -
Neutron Stars - Study of the Mass-Radius Relation and Mean-Field Approaches to the Equation of State
Pogliano, Francesco (Master thesis, 2017)The structure and the relation between the total mass, the radius and the central energy density of a neutron star may be found by numerically solving a set of three coupled differential equations. One of these equations ... -
Nonperturbative analysis of the electroweak phase transition in the two Higgs doublet model
Andersen, Jens Oluf; Gorda, Tyler; Helset, Andreas; Niemi, Lauri; Tenkanen, Tuomas V.I.; Tranberg, Anders; Vuorinen, Aleksi; Weir, David J. (Journal article; Peer reviewed, 2018)We perform a nonperturbative study of the electroweak phase transition (EWPT) in the two Higgs doublet model (2HDM) by deriving a dimensionally reduced high-temperature effective theory for the model, and matching to known ... -
Nuclear Equation of State and Neutron Stars
Strømberg, Caroline Brandt Kjelsen (Master thesis, 2017)In this thesis, we study the mass-radius relation of neutron stars. This relation is computed using stellar structure equations and an equation of state. We use the Tolman-Oppenheimer-Volkoff (TOV) equation and the mass ... -
On-shell parameter fixing in the quark-meson model
Adhikari, Prabal; Andersen, Jens Oluf; Kneschke, Patrick (Journal article; Peer reviewed, 2017)The quark-meson model is often used as an effective low-energy model for QCD to study the chiral transition at finite temperature T and baryon chemical potential μB. The parameters in the quark-meson model can be found by ... -
Particle creation in vacuum states using quantum field theory
Krumsvik, Alexander Refset (Master thesis, 2021)I denne masteravhandlingen introduserer vi en kvantisert felt-teori. Det kvantiserte feltet brukes til å vise at partikler blir skapt i tilstander som opprinnelig er vakum-tilstander, som betyr at det er ingen partikler ... -
Phases and condensates in zero-temperature QCD at finite μI and μS
Andersen, Jens Oluf (Peer reviewed; Journal article, 2022)I discuss pion and kaon condensation and the the properties of the phases of QCD at finite isospin chemical potential μI and strangeness chemical potential μS at zero temperature using three-flavor chiral perturbation ... -
Pion and kaon condensation at zero temperature in three-flavor χ\chiχPT at nonzero isospin and strange chemical potentials at next-to-leading order
Adhikari, Prabal; Andersen, Jens Oluf (Peer reviewed; Journal article, 2020)We consider three-flavor chiral perturbation theory (χPT) at zero temperature and nonzero isospin (µI ) and strange (µS) chemical potentials. The effective potential is calculated to next-to-leading order (NLO) in the π ... -
Pion condensation and phase diagram in the Polyakov-loop quark-meson model
Adhikari, Prabal; Andersen, Jens Oluf; Kneschke, Patrick (Journal article; Peer reviewed, 2018)We use the Polyakov-loop extended two-flavor quark-meson model as a low-energy effective model for QCD to study the phase diagram in the μI–T plane where μI is the isospin chemical potential. In particular, we focus on the ... -
Pion condensation and the QCD phase diagram at finite isospin density
Adhikari, Prabal; Andersen, Jens Oluf; Kneschke, Patrick (Journal article; Peer reviewed, 2019)We use the Polyakov-loop extended two-flavor quark-meson model as a low-energy effective model for QCD to study 1) the possibility of inhomogeneous chiral condensates and its competition with a homogeneous pion condensate ... -
Pion condensation in QCD at finite isospin density, the dilute Bose gas, and speedy Goldstone bosons
Andersen, Jens Oluf; Zhou, Hua; Yu, Qing (Journal article, 2024)We consider pion condensation in QCD at finite isospin density μI and zero temperature using two-flavor chiral perturbation theory (χPT). The pressure is calculated to next-to-leading order (NLO) in the low-energy expansion. ... -
Pion Condensation in the Linear Sigma Model
Almelid, Øyvind (Master thesis, 2011)In this thesis we study the phase diagram of quantum chromodynamics in an effective low-energy theory at zero baryon chemical potential but finite temperature and isospin density. We investigate pion condensation at finite ... -
Pion Stars: An Investigation of Chiral Perturbation Theory and Its Condensed Phases
Johnsrud, Martin Kjøllesdal (Master thesis, 2022)Muligheten for en ny type kompakte stjerner, navngitt pionstjerner, er nylig foreslått på teoretisk grunnlag. Pionstjerner er massive astrofysiske objekter bestående av et pionkondensat og holdt sammen av tyngdekraften. I ... -
QCD at finite isospin density: chiral perturbation theory confronts lattice data
Adhikari, Prabal; Andersen, Jens Oluf (Peer reviewed; Journal article, 2020)We consider the thermodynamics of three-flavor QCD in the pion-condensed phase at nonzero isospin chemical potential (μI) and vanishing temperature using chiral perturbation theory in the isospin limit. The transition from ... -
QCD phase diagram in a constant magnetic background: Inverse magnetic catalysis: where models meet the lattice
Andersen, Jens Oluf (Peer reviewed; Journal article, 2021)Magnetic catalysis is the enhancement of a condensate due to the presence of an external magnetic field. Magnetic catalysis at T=0 is a robust phenomenon in low-energy theories and models of QCD as well as in lattice ... -
Quantum Chromodynamics in Strong Magnetic Fields with Isospin Chemical Potential
Grønli, Martin Spillum (Master thesis, 2021)I denne avhandlingen studerer vi kvantekromodynamikk (QCD) med to kvarktyper ved lave energier. Vi inkluderer et eksternt magnetfelt og et endelig isospinn kjemisk potensial. Under disse forholdene vil grunntilstanden til ... -
Quantum corrections to slow-roll inflation: scalar and tensor modes
Andersen, Jens Oluf; Tranberg, Anders; Eriksson, Magdalena Britt (Peer reviewed; Journal article, 2021)Inflation is often described through the dynamics of a scalar field, slow-rolling in a suitable potential. Ultimately, this inflaton must be identified with the expectation value of a quantum field, evolving in a quantum ...