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Perturbative effective field theory expansions for cosmological phase transitions (2024)
Journal Article
Gould, O., & Tenkanen, T. V. I. (2024). Perturbative effective field theory expansions for cosmological phase transitions. Journal of High Energy Physics, 2024, Article 48. https://doi.org/10.1007/JHEP01%282024%29048

Guided by previous non-perturbative lattice simulations of a two-step electroweak phase transition, we reformulate the perturbative analysis of equilibrium thermodynamics for generic cosmological phase transitions in terms of effective field theory (... Read More about Perturbative effective field theory expansions for cosmological phase transitions.

BubbleDet: a Python package to compute functional determinants for bubble nucleation (2023)
Journal Article
Ekstedt, A., Gould, O., & Hirvonen, J. (2023). BubbleDet: a Python package to compute functional determinants for bubble nucleation. Journal of High Energy Physics, 2023(12), Article 56. https://doi.org/10.1007/jhep12%282023%29056

We present a Python package BubbleDet for computing one-loop functional determinants around spherically symmetric background fields. This gives the next-to-leading order correction to both the vacuum decay rate, at zero temperature, and to the bubble... Read More about BubbleDet: a Python package to compute functional determinants for bubble nucleation.

Higher orders for cosmological phase transitions: a global study in a Yukawa model (2023)
Journal Article
Gould, O., & Xie, C. (2023). Higher orders for cosmological phase transitions: a global study in a Yukawa model. Journal of High Energy Physics, 2023(12), Article 49. https://doi.org/10.1007/jhep12%282023%29049

We perform a state-of-the-art global study of the cosmological thermal histories of a simple Yukawa model, and find higher perturbative orders to be important for determining both the presence and strength of strong first-order phase transitions. Usi... Read More about Higher orders for cosmological phase transitions: a global study in a Yukawa model.

Cosmology with the Laser Interferometer Space Antenna (2023)
Journal Article
Auclair, P., Bacon, D., Baker, T., Barreiro, T., Bartolo, N., Belgacem, E., …Zhdanov, V. I. (2023). Cosmology with the Laser Interferometer Space Antenna. Living Reviews in Relativity, 26, Article 5. https://doi.org/10.1007/s41114-023-00045-2

The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and... Read More about Cosmology with the Laser Interferometer Space Antenna.

Opportunities for new physics searches with heavy ions at colliders (2023)
Journal Article
d’Enterria, D., Drewes, M., Giammanco, A., Hajer, J., Bratkovskaya, E., Bruce, R., …Upreti, A. (2023). Opportunities for new physics searches with heavy ions at colliders. Journal of Physics G: Nuclear and Particle Physics, 50(5), Article 050501. https://doi.org/10.1088/1361-6471/acc197

Opportunities for searches for phenomena beyond the Standard Model (BSM) using heavy-ions beams at high energies are outlined. Different BSM searches proposed in the last years in collisions of heavy ions, mostly at the Large Hadron Collider, are sum... Read More about Opportunities for new physics searches with heavy ions at colliders.

Early-Universe Model Building (2023)
Working Paper
Asadi, P., Bansal, S., Berlin, A., Co, R. T., Croon, D., Cui, Y., …Yu, H. (2023). Early-Universe Model Building

Theoretical investigations into the evolution of the early universe are an essential part of particle physics that allow us to identify viable extensions to the Standard Model as well as motivated parameter space that can be probed by various experim... Read More about Early-Universe Model Building.

First-order electroweak phase transitions: A nonperturbative update (2022)
Journal Article
Gould, O., Güyer, S., & Rummukainen, K. (2022). First-order electroweak phase transitions: A nonperturbative update. Physical Review D, 106(11), Article 114507. https://doi.org/10.1103/physrevd.106.114507

We study first-order electroweak phase transitions nonperturbatively, assuming any particles beyond the Standard Model are sufficiently heavy to be integrated out at the phase transition. Utilizing high temperature dimensional reduction, we perform l... Read More about First-order electroweak phase transitions: A nonperturbative update.

Radiative first-order phase transitions to next-to-next-to-leading order (2022)
Journal Article
Ekstedt, A., Gould, O., & Löfgren, J. (2022). Radiative first-order phase transitions to next-to-next-to-leading order. Physical Review D, 106(3), Article 036012. https://doi.org/10.1103/PhysRevD.106.036012

We develop new perturbative tools to accurately study radiatively induced first-order phase transitions. Previous perturbative methods have suffered internal inconsistencies and been unsuccessful in reproducing lattice data, which is often attributed... Read More about Radiative first-order phase transitions to next-to-next-to-leading order.

Search for magnetic monopoles produced via the Schwinger mechanism (2022)
Journal Article
Acharya, B., Alexandre, J., Benes, P., Bergmann, B., Bertolucci, S., Bevan, A., …Vives, O. (2022). Search for magnetic monopoles produced via the Schwinger mechanism. Nature, 602(7895), 63-67. https://doi.org/10.1038/s41586-021-04298-1

Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism1. By electromagnetic duality, a sufficiently strong magnetic field would similarly produce magnetic monopoles,... Read More about Search for magnetic monopoles produced via the Schwinger mechanism.

Effective field theory approach to thermal bubble nucleation (2021)
Journal Article
Gould, O., & Hirvonen, J. (2021). Effective field theory approach to thermal bubble nucleation. Physical Review D, 104(9), Article 096015. https://doi.org/10.1103/PhysRevD.104.096015

The standard vacuum bounce formalism suffers from inconsistencies when applied to thermal bubble nucleation, for which ad hoc workarounds are commonly adopted. Identifying the length scales on which nucleation takes place, we demonstrate how the cons... Read More about Effective field theory approach to thermal bubble nucleation.

Vacuum bubble collisions: From microphysics to gravitational waves (2021)
Journal Article
Gould, O., Sukuvaara, S., & Weir, D. (2021). Vacuum bubble collisions: From microphysics to gravitational waves. Physical Review D, 104(7), Article 075039. https://doi.org/10.1103/physrevd.104.075039

We comprehensively study the effects of bubble wall thickness and speed on the gravitational wave emission spectrum of collisions of two vacuum bubbles. We numerically simulate a large dynamical range, making use of symmetry to reduce the dimensional... Read More about Vacuum bubble collisions: From microphysics to gravitational waves.

Schwinger pair production of magnetic monopoles: Momentum distribution for heavy-ion collisions (2021)
Journal Article
Gould, O., Ho, D. L., & Rajantie, A. (2021). Schwinger pair production of magnetic monopoles: Momentum distribution for heavy-ion collisions. Physical Review D, 104(1), Article 015033. https://doi.org/10.1103/PhysRevD.104.015033

Magnetic monopoles may be produced by the dual Schwinger effect in strong magnetic fields. Today, the strongest known magnetic fields in the Universe are produced fleetingly in heavy-ion collisions. We use the complex worldline instanton method to ca... Read More about Schwinger pair production of magnetic monopoles: Momentum distribution for heavy-ion collisions.

On the perturbative expansion at high temperature and implications for cosmological phase transitions (2021)
Journal Article
Gould, O., & Tenkanen, T. V. I. (2021). On the perturbative expansion at high temperature and implications for cosmological phase transitions. Journal of High Energy Physics, 2021(06), Article 69. https://doi.org/10.1007/JHEP06%282021%29069

We revisit the perturbative expansion at high temperature and investigate its convergence by inspecting the renormalisation scale dependence of the effective potential. Although at zero temperature the renormalisation group improved effective potenti... Read More about On the perturbative expansion at high temperature and implications for cosmological phase transitions.

Theoretical uncertainties for cosmological first-order phase transitions (2021)
Journal Article
Croon, D., Gould, O., Schicho, P., Tenkanen, T. V., & White, G. (2021). Theoretical uncertainties for cosmological first-order phase transitions. Journal of High Energy Physics, 2021(4), Article 55. https://doi.org/10.1007/JHEP04%282021%29055

We critically examine the magnitude of theoretical uncertainties in perturbative calculations of fist-order phase transitions, using the Standard Model effective field theory as our guide. In the usual daisy-resummed approach, we find large uncertain... Read More about Theoretical uncertainties for cosmological first-order phase transitions.

Theoretical uncertainties for cosmological first-order phase transitions (2021)
Journal Article
Croon, D., Gould, O., Schicho, P., Tenkanen, T. V. I., & White, G. (2021). Theoretical uncertainties for cosmological first-order phase transitions. Journal of High Energy Physics, 2021(4), Article 55. https://doi.org/10.1007/JHEP04%282021%29055

We critically examine the magnitude of theoretical uncertainties in perturbative calculations of fist-order phase transitions, using the Standard Model effective field theory as our guide. In the usual daisy-resummed approach, we find large uncertain... Read More about Theoretical uncertainties for cosmological first-order phase transitions.

Real scalar phase transitions: a nonperturbative analysis (2021)
Journal Article
Gould, O. (2021). Real scalar phase transitions: a nonperturbative analysis. Journal of High Energy Physics, 2021(04), Article 57. https://doi.org/10.1007/JHEP04%282021%29057

We study the thermal phase transitions of a generic real scalar field, without a Z2-symmetry, referred to variously as an inert, sterile or singlet scalar, or ?3 + ?4 theory. Such a scalar field arises in a wide range of models, including as the infl... Read More about Real scalar phase transitions: a nonperturbative analysis.

New physics searches with heavy-ion collisions at the CERN Large Hadron Collider (2020)
Journal Article
Bruce, R., d'Enterria, D., de Roeck, A., Drewes, M., Farrar, G. R., Giammanco, A., …Heisig, J. (2020). New physics searches with heavy-ion collisions at the CERN Large Hadron Collider. Journal of Physics G: Nuclear and Particle Physics, 47(6), Article 060501. https://doi.org/10.1088/1361-6471/ab7ff7

This document summarises proposed searches for new physics accessible in the heavy-ion mode at the CERN Large Hadron Collider (LHC), both through hadronic and ultraperipheral γγ interactions, and that have a competitive or, even, unique discovery pot... Read More about New physics searches with heavy-ion collisions at the CERN Large Hadron Collider.

Nonperturbative analysis of the gravitational waves from a first-order electroweak phase transition (2019)
Journal Article
Gould, O., Kozaczuk, J., Niemi, L., Ramsey-Musolf, M. J., Tenkanen, T. V. I., & Weir, D. J. (2019). Nonperturbative analysis of the gravitational waves from a first-order electroweak phase transition. Physical Review D, 100, Article 115024. https://doi.org/10.1103/PhysRevD.100.115024

We present the first end-to-end nonperturbative analysis of the gravitational wave power spectrum from a thermal first-order electroweak phase transition (EWPT), using the framework of dimensionally reduced effective field theory and preexisting nonp... Read More about Nonperturbative analysis of the gravitational waves from a first-order electroweak phase transition.

Towards Schwinger production of magnetic monopoles in heavy-ion collisions (2019)
Journal Article
Gould, O., Ho, D. L. -., & Rajantie, A. (2019). Towards Schwinger production of magnetic monopoles in heavy-ion collisions. Physical Review D, 100, Article 015041. https://doi.org/10.1103/PhysRevD.100.015041

Magnetic monopoles may be produced by the Schwinger effect in the strong magnetic fields of peripheral heavy-ion collisions. We review the form of the electromagnetic fields in such collisions and calculate from first principles the cross section for... Read More about Towards Schwinger production of magnetic monopoles in heavy-ion collisions.

Worldline sphaleron for thermal Schwinger pair production (2018)
Journal Article
Gould, O., Rajantie, A., & Xie, C. (2018). Worldline sphaleron for thermal Schwinger pair production. Physical Review D, 98(5), 056022. https://doi.org/10.1103/physrevd.98.056022

With increasing temperatures, Schwinger pair production changes from a quantum tunneling to a classical, thermal process, determined by a worldline sphaleron. We show this and calculate the corresponding rate of pair production for both spinor and sc... Read More about Worldline sphaleron for thermal Schwinger pair production.

Magnetic monopole mass bounds from heavy ion collisions and neutron stars (2017)
Journal Article
Gould, O., & Rajantie, A. (2017). Magnetic monopole mass bounds from heavy ion collisions and neutron stars. Physical Review Letters, 119(24), Article 241601. https://doi.org/10.1103/PhysRevLett.119.241601

Magnetic monopoles, if they exist, would be produced amply in strong magnetic fields and high temperatures via the thermal Schwinger process. Such circumstances arise in heavy-ion collisions and in neutron stars, both of which imply lower bounds on t... Read More about Magnetic monopole mass bounds from heavy ion collisions and neutron stars.

Thermal Schwinger pair production at arbitrary coupling (2017)
Journal Article
Gould, O., & Rajantie, A. (2017). Thermal Schwinger pair production at arbitrary coupling. Physical Review D, 96(7), Article 076002. https://doi.org/10.1103/PhysRevD.96.076002

We calculate the rate of thermal Schwinger pair production at arbitrary coupling in weak external fields. Our calculations are valid independently of many properties of the charged particles produced, in particular their spin and whether they are ele... Read More about Thermal Schwinger pair production at arbitrary coupling.