• Quantum tunnelling, real-time dynamics and Picard-Lefschetz thimbles 

      Mou, Zonggang; Saffin, Paul M.; Tranberg, Anders (Peer reviewed; Journal article, 2019-11)
      We follow up the work, where in light of the Picard-Lefschetz thimble approach, we split up the real-time path integral into two parts: the initial density matrix part which can be represented via an ensemble of initial ...
    • Quarkonium phenomenology from a generalised Gauss law 

      Lafferty, David; Rothkopf, Alexander Karl (Peer reviewed; Journal article, 2019-05)
      We present an improved analytic parametrisation of the complex in-medium heavy quark potential derived rigorously from the generalised Gauss law. To this end we combine in a self-consistent manner a non-perturbative vacuum ...
    • Real-Time Complex Langevin - A Differential Programming Perspective 

      Alvestad, Daniel (PhD thesis UiS;, Doctoral thesis, 2023)
      In this thesis, I aim to find solutions to the NP-hard sign-problem that arises when modeling strongly correlated systems in real-time. I will use the complex Langevin (CLE) method, and address its problem of runaway ...
    • Second-Order PDEs in 3D with Einstein–Weyl Conformal Structure 

      Berjawi, S.; Ferapontov, E.V.; Kruglikov, Boris; Novikov, V.S. (Peer reviewed; Journal article, 2021)
      Einstein–Weyl geometry is a triple (D,g,ω) where D is a symmetric connection, [g] is a conformal structure and ω is a covector such that ∙ connection D preserves the conformal class [g], that is, Dg=ωg ; ∙ trace-free part ...
    • Signal analysis in gravitational wave data 

      Marcoccia, Paolo (PhD thesis UiS;, Doctoral thesis, 2024)
      In this thesis, I study the gravitational wave signals coming from compact objects on both present-stage, and future gravitational wave detectors. The thesis is based on 3 articles, which will be presented after two brief ...
    • Simulations of a bubble wall interacting with an electroweak plasma 

      Mou, Zong-Gang; Saffin, Paul M.; Tranberg, Anders (Peer reviewed; Journal article, 2021-02)
      We perform large-scale real-time simulations of a bubble wall sweeping through an out-of-equilibrium plasma. The scenario we have in mind is the electroweak phase transition, which may be first order in extensions of the ...
    • Soft Interactions in Cold Quark Matter 

      Gorda, Tyler; Kurkela, Eero Aleksi; Paatelainen, Risto; Säppi, Saga; Vuorinen, Aleksi (Peer reviewed; Journal article, 2021-10)
      Accurate knowledge of the thermodynamic properties of zero-temperature, high-density quark matter plays an integral role in attempts to constrain the behavior of the dense QCD matter found inside neutron-star cores, ...
    • Soft photon propagation in a hot and dense medium to next-to-leading order 

      Gorda, Tyler; Kurkela, Eero Aleksi; Österman, Juuso; Paatelainen, Risto; Säppi, Saga; Schicho, Philipp; Seppänen, Kaapo; Vuorinen, Aleksi (Peer reviewed; Journal article, 2023)
      We present the first complete calculation of the soft photon self-energy to the next-to-leading order in a hot and/or dense ultrarelativistic plasma in QED. The calculation is performed within the real-time formalism ...
    • Stable solvers for real-time Complex Langevin 

      Alvestad, Daniel; Larsen, Rasmus Normann; Rothkopf, Alexander Karl (Peer reviewed; Journal article, 2021-08)
      This study explores the potential of modern implicit solvers for stochastic partial differential equations in the simulation of real-time complex Langevin dynamics. Not only do these methods offer asymptotic stability, ...
    • Statistics on Lefschetz thimbles: Bell/Leggett-Garg inequalities and the classical-statistical approximation 

      Tranberg, Anders; Millington, P; Mou, Zonggang; Saffin, Paul M. (Peer reviewed; Journal article, 2021)
      Inspired by Lefschetz thimble theory, we treat Quantum Field Theory as a statistical theory with a complex Probability Distribution Function (PDF). Such complex-valued PDFs permit the violation of Bell-type inequalities, ...
    • Stochastic gravitational wave background from stellar origin binary black holes in LISA 

      Babak, Stanislav; Caprini, Chiara; Figueroa, Daniel G.; Karnesis, Nikolaos; Marcoccia, Paolo; Nardini, Germano; Pieroni, Mauro; Ricciardone, Angelo; Sesana, Alberto; Torrado, Jesús (Peer reviewed; Journal article, 2023)
      We use the latest constraints on the population of stellar origin binary black holes (SOBBH) from LIGO/Virgo/KAGRA (LVK) observations, to estimate the stochastic gravitational wave background (SGWB) they generate in the ...
    • Stochastic inflation from quantum field theory and the parametric dependence of the effective noise amplitude 

      Andersen, Jens Oluf; Tranberg, Anders; Eriksson, Magdalena Britt (Peer reviewed; Journal article, 2022-02)
      The non-linear dynamics of long-wavelength cosmological fluctuations may be phrased in terms of an effective classical, but stochastic evolution equation. The stochastic noise represents short-wavelength modes that continually ...
    • Symmetry and Equivalence in Teleparallel Gravity 

      Coley, Alan; van den Hoogen, Robert; McNutt, David Duncan (Peer reviewed; Journal article, 2020-07)
      In theories such as teleparallel gravity and its extensions, the frame basis replaces the metric tensor as the primary object of study. A choice of coordinate system, frame basis, and spin-connection must be made to obtain ...
    • T3-invariant heterotic Hull-Strominger solutions 

      Svanes, Eirik Eik; Acharya, Bobby S.; Kinsella, Alex (Peer reviewed; Journal article, 2021-01)
      We consider the heterotic string on Calabi-Yau manifolds admitting a Strominger-Yau-Zaslow fibration. Upon reducing the system in the T3-directions, the Hermitian Yang-Mills conditions can then be reinterpreted as a complex ...
    • Tales from Wonderland 

      Normann, Ben David (Doctoral thesis, 2020-06)
      Knowing that the Universe is quite isotropic, one may, as already discussed in Chapter 1, wonder how likely such a Universe is. We take the following research question. Question 1. Is the asymptotic future of a cosmology ...
    • Thermalization and dynamical spectral properties in the quark-meson model 

      Shen, Lisa; Berges, Jürgen; Pawlowski, Jan M.; Rothkopf, Alexander Karl (Peer reviewed; Journal article, 2020-07)
      We investigate the nonequilibrium evolution of the quark-meson model using two-particle irreducible effective action techniques. Our numerical simulations, which include the full dynamics of the order parameter of chiral ...
    • Thermalization of weakly coupled non-Abelian plasmas at next-to-leading order 

      Fu, Yu; Ghiglieri, Jacopo; Iqbal, Shahin; Kurkela, Eero Aleksi (Peer reviewed; Journal article, 2023)
      We employ the QCD kinetic theory, including next-to-leading(NLO) order corrections in coupling constant, to study the evolution of weakly coupled non-Abelian plasmas towards thermal equilibrium. For two characteristic ...
    • Thermodynamics of antiferromagnetic solids in magnetic fields 

      Brauner, Tomas; Hofmann, Christoph (Peer reviewed; Journal article, 2020)
      We analyze the thermodynamic properties of antiferromagnetic solids subjected to a combination of mutually orthogonal uniform magnetic and staggered fields. Low- temperature series for the pressure, order parameter and ...
    • Thoughts about the utility of perturbative QCD in the cores of neutron stars – contribution to a roundtable discussion on neutron stars and QCD 

      Kurkela, Eero Aleksi (Peer reviewed; Journal article, 2022)
      In this contribution, I discuss the utility that perturbative QCD offers in studying the matter in the cores of neutron stars. I discuss the reasons why perturbative QCD can constrain the equation of state at densities far ...
    • Topological G2 and Spin(7) strings at 1-loop from double complexes 

      Ashmore, Anthony; Coimbra, André; Strickland-Constable, Charles; Svanes, Eirik Eik; Tennyson, David (Peer reviewed; Journal article, 2022)
      We study the topological G2 and Spin(7) strings at 1-loop. We define new double complexes for supersymmetric NSNS backgrounds of string theory using generalised geometry. The 1-loop partition function then has a target-space ...