The decay $\eta\to\pi^+\pi^- \pi^0$ is an ideal channel in which to study flavor-conserving $C$ and $CP$ violation beyond the Standard Model. We use Standard Model Effective Field Theory (SMEFT) to deduce the mass-dimension-six operators that can contribute to its signature, i.e., an observed breaking of mirror symmetry in its Dalitz plot. Using chiral-effective theory, we present the leading...
Currently and in the near future, a variety of $\eta$ factories are exploring the potential to search for new physics through different $\eta$ decays. One possibility being considered is to search for signs of CP-violation in eta decays. Since the Standard Model predicts an extremely suppressed rate for CP-violation in the $\eta$ sector, any positive signal would be a clear sign of new...
The system of η and η′ offers a flavor-conserving laboratory to test the low-energy QCD and to search for new physics Beyond the Standard Model. The symmetry properties of QCD at low-energy, such as the chiral symmetry or the axial anomalies, are manifested in the decays of η and η′. Thus, a study of η/η′ will yield light on our understanding of the origin and the dynamics of QCD...
The talk will include recent progress and insights on eta/eta' decays at KLOE/KLOE2 and the propest in this field that could be achieved with the future e+e- collider proposed like STCF.
Dark photons arising at or below the GeV scale from a spontaneously broken gauge symmetry are one of the simplest and most exciting extensions of the Standard Model. They couple to known particles via kinetic mixing with the Standard Model gauge bosons and can act as mediators between visible matter and new hidden states, such as sub-GeV dark matter particles. I will show that these models can...
The goal of the new JLab Eta Factory (JEF) experiment, conducted with the GlueX detector in Hall D at Jefferson Lab, is to perform measurements of various $\eta^{(\prime)}$ decays with a primary focus on rare neutral modes. The experiment's physics program ranges from precision tests of low-energy QCD to searches for gauge bosons with masses below 1 GeV that could couple the Standard Model...
The uncertainty of the Standard Model prediction of the anomalous magnetic moment of the muon $(g-2)_\mu$ is dominated by hadronic contributions. As part of these hadronic inputs, the pseudoscalar-pole contribution in hadronic-light-by-light scattering plays a vital role. The currently sought precision of the Standard Model prediction of $(g-2)_\mu$ requires a careful evaluation not only of...
Novel trigger strategies, combined with the large proton-proton collision datasets collected by the CMS experiment, have extended its sensitivity to rare flavor decay processes. Leveraging CMS’s ability to efficiently trigger on and reconstruct low-momentum muons, the experiment offers complementary sensitivity to rare meson decays.
This contribution presents recent results on η meson...
The recently reported evidence of a Stochastic Gravitational Wave Background (SGWB) in the nHz frequency range is in tension with standard astrophysical expectations, motivating the study of new physics beyond the Standard Model. A preferred explanation relies on a supercooled first order phase transition at the 100 MeV - GeV scale. I will present a minimal model that can account for the SGWB,...
This talk will provide an overview of the precise higher-order calculation in the anomalous sector. The focus will be on the two-photon decays for pion and eta and on the corresponding Dalitz decays.
We analyse vector, scalar and tensor meson-exchange contributions to the doubly radiative decays $\eta^{(\prime)}\to\pi^0\gamma\gamma$ and $\eta^{\prime}\to\eta\gamma\gamma$, and investigate the sensitivity of these processes to a leptophobic $B$ boson in the sub-GeV mass range. Our results are relevant for measurements of these decays at existing (A2, BESIII, KLOE-2) and forthcoming...
With upcoming $\eta/\eta^{\prime}$ factories in the horizon, dedicated searches for hadronic ALPs would open a new window into the exploration of strong CP solutions and low scale dark sectors. In this talk, we present branching ratio sensitivities of the axio-hadronic $\eta/\eta^{\prime}\to\pi\pi a$ decays, where $a$ is an axion or axion-like particle (ALP), using the leading order ALP-ChPT...
