Outputs (70)

Quantum tunnelling, real-time dynamics and Picard-Lefschetz thimbles (2019)
Journal Article
Mou, Z.-G., Saffin, P. M., & Tranberg, A. (2019). Quantum tunnelling, real-time dynamics and Picard-Lefschetz thimbles. Journal of High Energy Physics, 2019(11), Article 135. https://doi.org/10.1007/jhep11%282019%29135

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 conditions, and the dynamic pa... Read More about Quantum tunnelling, real-time dynamics and Picard-Lefschetz thimbles.

Visualising quantum effective action calculations in zero dimensions (2019)
Journal Article
Millington, P., & Saffin, P. M. (2019). Visualising quantum effective action calculations in zero dimensions. Journal of Physics A: Mathematical and Theoretical, 52(40), Article 405401. https://doi.org/10.1088/1751-8121/ab37e6

© 2019 IOP Publishing Ltd. We present an explicit treatment of the two-particle-irreducible (2PI) effective action for a zero-dimensional quantum field theory. The advantage of this simple playground is that we are required to deal only with function... Read More about Visualising quantum effective action calculations in zero dimensions.

Real-time quantum dynamics, path integrals and the method of thimbles (2019)
Journal Article
Mou, Z.-G., Saffin, P. M., Tranberg, A., & Woodward, S. (2019). Real-time quantum dynamics, path integrals and the method of thimbles. Journal of High Energy Physics, 2019(6), Article 94. https://doi.org/10.1007/jhep06%282019%29094

Direct numerical evaluation of the real-time path integral has a well-known sign problem that makes convergence exponentially slow. One promising remedy is to use Picard-Lefschetz theory to flow the domain of the field variables into the complex plan... Read More about Real-time quantum dynamics, path integrals and the method of thimbles.

Well-tempered cosmology (2019)
Journal Article
Emond, W. T., Li, C., Saffin, P. M., & Zhou, S.-Y. (2019). Well-tempered cosmology. Journal of Cosmology and Astroparticle Physics, 2019(05), Article 038. https://doi.org/10.1088/1475-7516/2019/05/038

We examine an approach to cosmology, known as Well-Tempering, that allows for a de Sitter phase whose expansion is independent of the cosmological constant. Starting from a generic scalar-tensor theory compatible with the recent gravitational wave ob... Read More about Well-tempered cosmology.

Dark Energy after GW170817 Revisited (2019)
Journal Article
Copeland, E. J., Kopp, M., Padilla, A., Saffin, P. M., & Skordis, C. (2019). Dark Energy after GW170817 Revisited. Physical Review Letters, 122(6), Article 061301. https://doi.org/10.1103/physrevlett.122.061301

We revisit the status of scalar-tensor theories with applications to dark energy in the aftermath of the gravitational wave signal GW170817 and its optical counterpart GRB170817A. At the level of the cosmological background, we identify a class of th... Read More about Dark Energy after GW170817 Revisited.

Higher order clockwork gravity (2018)
Journal Article
Niedermann, F., Padilla, A., & Saffin, P. M. (2018). Higher order clockwork gravity. Physical Review D, 98(10), Article 104014. https://doi.org/10.1103/physrevd.98.104014

We present a higher order generalisation of the clockwork mechanism starting from an underlying non-linear multigravity theory with a single scale and nearest neighbour ghost-free interactions. Without introducing any hierarchies in the underlying po... Read More about Higher order clockwork gravity.

Boltzmann equations for preheating (2018)
Journal Article
Emond, W. T., Millington, P., & Saffin, P. M. (2018). Boltzmann equations for preheating. Journal of Cosmology and Astroparticle Physics, 2018(09), Article 041. https://doi.org/10.1088/1475-7516/2018/09/041

We derive quantum Boltzmann equations for preheating by means of the density matrix formalism, which account for both the non-adiabatic particle production and the leading collisional processes between the produced particles. In so doing, we illustra... Read More about Boltzmann equations for preheating.

Rotating kinky braneworlds (2018)
Journal Article
Niedermann, F., & Saffin, P. M. (2018). Rotating kinky braneworlds. Journal of High Energy Physics, 2018(7), Article 183. https://doi.org/10.1007/jhep07%282018%29183

Cylindrical braneworlds have been used in the literature as a convenient way to resolve co-dimension-two branes. They are prevented from collapsing by a massless worldvolume field with non-trivial winding, but here we discuss another way of preventin... Read More about Rotating kinky braneworlds.

Simulations of cold electroweak baryogenesis: dependence on the source of CP-violation (2018)
Journal Article
Mou, Z.-G., Saffin, P. M., & Tranberg, A. (2018). Simulations of cold electroweak baryogenesis: dependence on the source of CP-violation. Journal of High Energy Physics, 2018(5), Article 197. https://doi.org/10.1007/JHEP05%282018%29197

We compute the baryon asymmetry created in a tachyonic electroweak symmetry breaking transition, focusing on the dependence on the source of effective CP-violation. Earlier simulations of Cold Electroweak Baryogenesis have almost exclusively consider... Read More about Simulations of cold electroweak baryogenesis: dependence on the source of CP-violation.

Simulations of Cold Electroweak Baryogenesis: quench from portal coupling to new singlet field (2018)
Journal Article
Mou, Z.-G., Saffin, P. M., & Tranberg, A. (2018). Simulations of Cold Electroweak Baryogenesis: quench from portal coupling to new singlet field. Journal of High Energy Physics, 2018(1), Article 103. https://doi.org/10.1007/JHEP01%282018%29103

We compute the baryon asymmetry generated from Cold Electroweak Baryogenesis, when a dynamical Beyond-the-Standard-Model scalar singlet field triggers the spinodal transition. Using a simple potential for this additional field, we match the speed of... Read More about Simulations of Cold Electroweak Baryogenesis: quench from portal coupling to new singlet field.