Browsing UiS Brage by Author "Tranberg, Anders"
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Bubble nucleation and quantum initial conditions in classical statistical simulations
Tranberg, Anders; Ungersbäck, Gerhard (Peer reviewed; Journal article, 2022)Classicalstatistical lattice simulations provide a useful approximation to outofequilibrium quantum field theory, but only for systems exhibiting large occupation numbers, and only for phenomena that are not intrinsically ... 
Chiral and deconfinement transitions in a magnetic background using the functional renormalization group with the Polyakov loop
Andersen, Jens Oluf; Naylor, William; Tranberg, Anders (Journal article; Peer reviewed, 201404)We use the Polyakov loop coupled quarkmeson model to approximate low energy QCD and present results for the chiral and deconﬁnement transitions in the presence of a constant magnetic background B at ﬁnite temperature T ... 
Chiral and deconfinement transitions in a magnetic background using the functional renormalization group with the Polyakov loop
Andersen, Jens O.; Naylor, William R.; Tranberg, Anders (Journal article; Peer reviewed, 201404)We use the Polyakov loop coupled quarkmeson model to approximate low energy QCD and present results for the chiral and deconfinement transitions in the presence of a constant magnetic background B at finite temperature T ... 
Cold Baryogenesis from first principles in the twoHiggs doublet model with fermions
Mou, ZongGang; Saffin, Paul M.; Tranberg, Anders (Journal article; Peer reviewed, 201506)We present a firstprinciples numerical computation of the baryon asymmetry in electroweakscale baryogenesis. For the scenario of Cold Baryogenesis, we consider a one fermionfamily reduced CPviolating two Higgsdoublet ... 
Detecting gravitational waves from cosmological phase transitions with LISA: an update
Caprini, Chiara; Chala, Mikael; Dorsch, Glauber C.; Hindmarsh, Mark; Huber, Stephan J.; Konstandin, Thomas; Kozaczuk, Jonathan; Nardini, Germano; No, Jose Miguel; Rummukainen, Kari; Schwaller, Pedro; Servant, Geraldine; Tranberg, Anders; Weir, David J. (Peer reviewed; Journal article, 2020)We investigate the potential for observing gravitational waves from cosmological phase transitions with LISA in light of recent theoretical and experimental developments. Our analysis is based on current stateoftheart ... 
Dimensional reduction of the Standard Model coupled to a new singlet scalar field
Brauner, Tomas; Tenkanen, Tuomas; Tranberg, Anders; Vuorinen, Aleksi; Weir, David James (Journal article; Peer reviewed, 2017)We derive an effective dimensionally reduced theory for the Standard Model augmented by a real singlet scalar. We treat the singlet as a superheavy field and integrate it out, leaving an effective theory involving only the ... 
Effective field theory and electroweak baryogenesis in the singletextended Standard Model
Damgaard, P.H.; Haarr, A.; O'Connell, D.; Tranberg, Anders (Journal article; Peer reviewed, 201602)Electroweak baryogenesis is a simple and attractive candidate mechanism for generating the observed baryon asymmetry in the Universe. Its viability is sometimes investigated in terms of an effective field theory of the ... 
Gravitational waves from tachyonic preheating
Hetland, Bjarte (Masteroppgave/UISTNIMN/2017;, Master thesis, 201706)Most models of the universe, which are in agreement with current observations, include some form of extremely rapid expansion of space at a very early stage. This is called cosmological inflation, or just inflation. Most ... 
Inverse magnetic catalysis and regularization in the quarkmeson model
Andersen, Jens O.; Naylor, William R.; Tranberg, Anders (Journal article; Peer reviewed, 201502)Motivated by recent work on inverse magnetic catalysis at finite temperature, we study the quarkmeson model using both dimensional regularization and a sharp cutoff. We calculate the critical temperature for the chiral ... 
Nonequilibrium quantum field dynamics in the early Universe
Eriksson, Magdalena (PhD thesis UiS;, Doctoral thesis, 2023)Inflation is the leading paradigm of early Universe cosmology. It provides compelling explanations of the observed nearhomogeneity of the cosmic microwave background (CMB) radiation, the spatial flatness of the Universe ... 
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, 201811)We perform a nonperturbative study of the electroweak phase transition (EWPT) in the two Higgs doublet model (2HDM) by deriving a dimensionally reduced hightemperature effective theory for the model, and matching to known ... 
Optimisation of Thimble simulations and quantum dynamics of multiple fields in real time
Woodward, Simon; Saffin, Paul M.; Mou, Zonggang; Tranberg, Anders (Peer reviewed; Journal article, 2022)We apply the Generalised Thimble approach to the computation of exact path integrals and correlators in realtime quantum field theory. We first investigate the details of the numerical implementation and ways of optimizing ... 
Quantum corrections to slowroll inflation: scalar and tensor modes
Andersen, Jens Oluf; Eriksson, Magdalena Britt; Tranberg, Anders (Peer reviewed; Journal article, 2021)Inflation is often described through the dynamics of a scalar field, slowrolling in a suitable potential. Ultimately, this inflaton must be identified with the expectation value of a quantum field, evolving in a quantum ... 
Quantum tunnelling, realtime dynamics and PicardLefschetz thimbles
Mou, Zonggang; Saffin, Paul M.; Tranberg, Anders (Peer reviewed; Journal article, 201911)We follow up the work, where in light of the PicardLefschetz thimble approach, we split up the realtime path integral into two parts: the initial density matrix part which can be represented via an ensemble of initial ... 
Realtime quantum dynamics, path integrals and the method of thimbles
Mou, Zonggang; Saffin, Paul M.; Tranberg, Anders; Woodward, Simon (Peer reviewed; Journal article, 2019)Direct numerical evaluation of the realtime path integral has a wellknown sign problem that makes convergence exponentially slow. One promising remedy is to use PicardLefschetz theory to flow the domain of the field ... 
Simulations of "tunnelling of the 3rd kind"
Mou, Zonggang; Saffin, Paul M.; Tognarelli, Paul; Tranberg, Anders (Journal article; Peer reviewed, 201707)We consider the phenomenon of “tunnelling of the 3rd kind” [1], whereby a magnetic field may traverse a classically impenetrable barrier by pair creation of unimpeded quantum fermions. These propagate through the barrier ... 
Simulations of a bubble wall interacting with an electroweak plasma
Mou, ZongGang; Saffin, Paul M.; Tranberg, Anders (Peer reviewed; Journal article, 202102)We perform largescale realtime simulations of a bubble wall sweeping through an outofequilibrium plasma. The scenario we have in mind is the electroweak phase transition, which may be first order in extensions of the ... 
Simulations of Cold Electroweak Baryogenesis: finding the optimal quench time
Mou, Zonggang; Saffin, Paul M.; Tranberg, Anders (Journal article; Peer reviewed, 201707)We revisit the numerical computation of the baryon asymmetry from Cold Electroweak Baryogenesis given the physical Higgs mass. We investigate the dependence of the asymmetry on the speed at which electroweak symmetry ... 
Simulations of Cold Electroweak Baryogenesis: hypercharge U(1) and the creation of helical magnetic fields
Mou, Zonggang; Saffin, Paul M.; Tranberg, Anders (Journal article; Peer reviewed, 201706)We perform numerical simulations of Cold Electroweak Baryogenesis, including for the first time in the Bosonic sector the full electroweak gauge group SU(2) × U(1) and CPviolation. We find that the maximum generated baryon ... 
Statistics on Lefschetz thimbles: Bell/LeggettGarg inequalities and the classicalstatistical 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 complexvalued PDFs permit the violation of Belltype inequalities, ...