Gravitational waves from a supercooled electroweak phase transition and their detection with pulsar timing arrays

We investigate the properties of a stochastic gravitational wave background produced by a first-order electroweak phase transition in the regime of extreme supercooling. We study a scenario whereby the percolation temperature that signifies the completion of the transition, $T_p$, can be as low as a few MeV (nucleosynthesis temperature), while most of the true vacuum bubbles are formed much earlier at the nucleation temperature, $T_n\sim 50$ GeV. This implies that the gravitational wave spectrum is mainly produced by the collisions of large bubbles and characterised by a large amplitude and a peak frequency as low as $f \sim 10^{-9}-10^{-7}$ Hz. We show that such a scenario can occur in (but not limited to) a model based on a non-linear realisation of the electroweak gauge group, such that the Higgs vacuum configuration is altered by a cubic coupling. In order to carefully quantify the evolution of the phase transition of this model over such a wide temperature range, we go beyond the usual fast transition approximation, taking into account the expansion of the universe as well as the behaviour of the nucleation probability at low temperatures. Our computation shows that there exists a range of parameters for which the gravitational wave spectrum lies at the edge between the exclusion limits of current pulsar timing array experiments and the detection band of the future Square Kilometre Array observatory.

Comments: 20 pages, 3 figures

Similar Publications

The proposed Deep Underground Neutrino Experiment (DUNE) utilizes a wide-band on-axis tunable muon-(anti)neutrino beam with a baseline of 1300 km to search for CP violation with high precision. Given the long baseline, DUNE is also sensitive to effects due to non-standard neutrino interactions (NSI) which can interfere with the standard 3-flavor oscillation paradigm. In this Letter, we exploit the tunability of the DUNE neutrino beam over a wide-range of energies and utilize a new theoretical metric to devise an experimental strategy for separating oscillation effects due to NSI from the standard 3-flavor oscillation scenario. Read More

The possibility of the existence of right-handed neutrinos remains one of the most important open questions in particle physics, as they can help elucidate the problems of neutrino masses, matter-antimatter asymmetry, and dark matter. Interest in this topic has been increasing in recent years with the proposal of new experimental avenues by which right-handed neutrinos with masses below the electroweak scale could be detected directly using displaced-vertex signatures. At the forefront of such endeavours, the proposed SHiP proton beam-dump experiment is designed for a large acceptance to new weakly-coupled particles and low backgrounds. Read More

We calculate the masses and weak decay constants of flavorless ground and radially excited $J^P=1^-$ mesons and the corresponding quantities for the K^*, within a Poincar\'e covariant continuum framework based on the Bethe-Salpeter equation. We use in both, the quark's gap equation and the meson bound-state equation, an infrared massive and finite interaction in the leading symmetry-preserving truncation. While our numerical results are in rather good agreement with experimental values where they are available, no single parametrization of the QCD inspired interaction reproduces simultaneously the ground and excited mass spectrum, which confirms earlier work on pseudoscalar mesons. Read More

We show the SM prediction of di-lepton production at the LHC where to the usual Drell-Yan production we add the contribution from Photon-Initiated processes. We discuss the effects of the inclusion of photon interactions in the high invariant mass region (TeV region) and their consequences on BSM heavy Z'-boson searches. Read More

We propose a Higgs triplet model with $U(1)_{B-L}$ gauge symmetry and several new fermions in no conflict with anomaly cancellation where the neutrino masses are given by the vacuum expectation value of Higgs triplet induced at the one-loop level. The new fermions are odd under discrete $Z_2$ symmetry and the lightest one becomes dark matter candidate. We find that the mass of dark matter is typically $\mathcal{O}(1)$-$\mathcal{O}(10)$ GeV. Read More

I give an overview of recent progress in the simulation of final states involving top-quarks and vector bosons pair. First I'll discuss the recently found solutions needed to simulate fully differential top pair production ($pp\to b\bar{b}$ + 4 leptons) at NLO+PS accuracy, retaining off-shellness and interference effects exactly. In the second part, I'll review the MiNLO (Multi-scale Improved NLO) method, and then show a recent application, namely the simultaneous NLO+PS description of $W^+W^-$ and $W^+W^- +$ 1 jet production. Read More

We report on the lattice calculations of the heavy quark potential at $T>0$ in 2+1 flavor QCD at physical quark masses using the Highly Improved Staggered Quark discretization. We study in detail the systematic effects in the determination of the real and imaginary parts of the potential when using the moment method. Read More

We discuss in detail the spatial distribution of angular momentum inside the nucleon. We show that the discrepancies between different definitions originate from terms that integrate to zero. Even though these terms can safely be dropped at the integrated level, they have to be taken into account at the density level. Read More

We release fastNLO tables with NNLO QCD top-quark pair differential distributions corresponding to 8 TeV ATLAS [Eur. Phys. J. Read More

I present higher-order radiative corrections from collinear and soft gluon emission for the associated production of a charged Higgs boson with a $W$ boson. The calculation uses expressions from resummation at next-to-leading-logarithm accuracy. From the resummed cross section I derive approximate next-to-next-to-leading order (aNNLO) cross sections for the process $b{\bar b} \rightarrow H^- W^+$ at LHC energies. Read More