arXiv subjects

Guotao Xia

Publications and source records attributed to Guotao Xia.

3 recordsLinked to original sources

arXiv2026

Constraining the real singlet extension of the Standard Model: implications for vacuum stability

Amongst the simplest extensions of the Standard Model is the addition of a real singlet scalar field with profound phenomenological consequences. The singlet can catalyze a strong first-order electroweak phase transition, necessary for successful electroweak baryogenesis. Furthermore, the current prediction of a metastable Higgs vacuum can be lifted towards absolute stability. While current data mainly constrain the scalar mixing angle, future measurements of the Higgs self-coupling and direct searches for additional scalar states will probe much larger parts of the viable parameter space. We report on a combined study of theoretical and experimental constraints on the real singlet extension, highlighting here in particular its implications for vacuum stability.

hep-ph↗

arXiv2026

Constraining the real scalar singlet extension of the SM

The real scalar singlet extension of the standard model provides a minimal framework in which the Higgs sector can realise a strong first-order electroweak phase transition and improve the stability of the electroweak vacuum. We combine the electroweak phase transition and high-scale vacuum stability with current and projected collider probes, including precision Higgs measurements, the Higgs trilinear coupling, EWPO and resonant searches for a heavy singlet-like scalar in $ZZ$ and di-Higgs final states. Focusing on a singlet heavier than the standard model Higgs, we find that there is parameter space compatible with a strong first-order electroweak phase transition for singlet-like scalar masses up to nearly 1 TeV. Deviations in the Higgs self-coupling can be larger than those in the Higgs--$Z$ coupling, making Higgs-potential measurements a key probe. We find that the HL-LHC will test a large fraction of the parameter space, while the FCC will provide ultimate discovery and model-discrimination capabilities.

hep-ph↗

arXiv2024

Nonperturbative study of the electroweak phase transition in the real scalar singlet extended Standard Model

We perform a nonperturbative lattice study of the electroweak phase transition in the real singlet scalar extension of the Standard Model.We consider both the heavy and light singlet-like scalar regimes at non-zero singlet-doublet mixing angle. After reviewing features of the lattice method relevant for phase transition studies, we analyze the dependence of phase transition thermodynamics on phenomenologically relevant parameters. In the heavy singlet-like scalar regime, we find that the transition is crossover for small doublet-singlet mixing angles, despite the presence of an energy barrier in the tree-level potential. The transition becomes first order for sufficiently large mixing angles. We find two-loop perturbation theory to agree closely with the lattice results for all thermodynamical quantities considered here (critical temperature, order parameter discontinuity, latent heat) when the transition is strongly first order. For the light singlet-like scalar regime relevant to exotic Higgs decays, we update previous one-loop perturbative results using the two-loop loop dimensionally reduced effective field theory and assess the nature of the transition with lattice simulations at set of benchmark parameter points. For fixed singlet-like scalar mass the transition becomes crossover when the magnitude of the Higgs-singlet portal coupling is small. We perform our simulations in the high-temperature effective theory, which we briefly review, and present analytic expressions for the relevant lattice-continuum relations.

hep-ph↗