arXiv subjects

Jintao Zou

Publications and source records attributed to Jintao Zou.

3 recordsLinked to original sources

arXiv2026

Simulating first-order phase transition during inflation

Ending the inflation by vacuum decay is considered infeasible due to the graceful exit problem. Even if considering an alternative field other than the inflaton to realize a first-order phase transition (FoPT) during inflation, it is usually challenging for concrete model building, as bubble nucleations might not be fast and dense enough to successfully end the inflation. In this work, we propose a FoPT at the grand-unification-theory (GUT) scale within the Starobinsky inflation. The key construction is an exponentially evolving potential barrier dynamically controlled by the rolling inflaton, so that almost no bubble is nucleated during the early inflationary era, but with massive bubble nucleations near the end of inflation. With lattice numerical simulations, we have successfully tested this GUT-FoPT during Starobinsky inflation, and the resulting gravitational-wave energy density spectrum reproduces previous analytical estimation with a distinctive oscillation feature at high frequencies.

hep-ph↗

arXiv2025

Numerical simulations of density perturbation and gravitational wave production from cosmological first-order phase transition

We conducted three-dimensional lattice simulations to study the density perturbation and gravitational waves (GWs) during first-order phase transition (FOPT). We find that for phase transition strength $\alpha > 1$, the forward motion of bubble walls becomes the primary source, whereas for $\alpha < 1$, the dominant contribution to the density perturbation comes from the delay of vacuum decay. Additionally, the power spectrum of density perturbations generated by the phase transition exhibits a slope of $k^3$ at small wavenumbers and $k^{-1.5}$ at large wavenumbers. Furthermore, we calculated the GW power spectra, which exhibit the slope of $k^3$ at small wavenumbers and $k^{-2}$ at large wavenumbers. Our numerical simulations confirm that slow PTs can produce PBHs and provide predictions for the GW power spectrum, offering theoretical support for GW detection.

hep-ph↗

arXiv2024

The radiative decay of scalar glueball from lattice QCD

We perform the first lattice QCD study on the radiative decay of the scalar glueball to the vector meson $ϕ$ in the quenched approximation. The calculations are carried out on three gauge ensembles with different lattice spacings, which enable us to do the continuum extrapolation. We first revisit the radiative $J/ψ$ decay into the scalar glueball $G$ and obtain the partial decay width $Γ(J/ψ\to γG)=0.578(86)~\text{keV}$ and the branching fraction $\text{Br}(J/ψ\to γG) = 6.2(9)\times 10^{-3}$. We then extend the similar calculation to the process $G\to γϕ$ and get the partial decay width $Γ(G \to γϕ)= 0.074(47)~\text{keV}$, which implies that the combined branching fraction of $J/ψ\toγG\to γγϕ$ is as small as $\mathcal{O}(10^{-9})$ such that this process is hardly detected by the BESIII experiment even with the large $J/ψ$ sample of $\mathcal{O}(10^{10})$. With the vector meson dominance model, the two-photon decay width of the scalar glueball is estimated to be $Γ(G\toγγ)=0.53(46)~\text{eV}$, which results in a large stickiness $S(G)\sim \mathcal{O}(10^4)$ of the scalar glueball by assuming the stickiness of $f_2(1270)$ to be one.

hep-lat↗