arXiv subjects

Sofia Giappichini

Publications and source records attributed to Sofia Giappichini.

3 recordsLinked to original sources

arXiv2026

CP violation angles from H$\toττ$ decays at FCC-ee

Measuring charge-parity (CP) violation in Higgs-fermion interactions is a key target of future precision Higgs programs. The decay $H\toττ$ is particularly sensitive to the CP structure of the Higgs Yukawa coupling via $τ$ spin correlation, while the clean environment of $e^+e^-$ collisions at the Future Circular Collider (FCC) enables accurate reconstruction of CP-sensitive observables. In this letter, we study the sensitivity of FCC-ee to the Higgs CP state using $H\toττ$ events produced in associated $ZH$ production at $\sqrt{s}=240$ GeV. In the anomalous-coupling parametrization, we project a precision of $Δϕ_{ττ}=\pm 2.5^\circ$ at 68 % CL, with the dominant contribution arising from one-prong hadronic $τ$ decays. We further interpret the analysis in the Effective Field Theory framework, deriving expected limits on the CP-odd operators, and compare them with electron and magnetic dipole moment measurements and the anomalous-coupling approach.

hep-ph↗

arXiv2026

Projections of H$\toττ$ cross-section at FCC-ee

The Future Circular Collider (FCC) stands at the forefront of the European Strategy for Particle Physics as the future flagship project at CERN. The H$\toττ$ decay, featuring a large branching ratio, clean identification in the FCC-ee environment, and the possibility to reconstruct polarization information, is an excellent channel to measure Higgs boson properties. This work shows the expected precision for the H$\toττ$ cross-section measurement at the FCC-ee in the ZH production mechanism at $\sqrt{s}=$240 GeV and $\sqrt{s}=$365 GeV, as well as via the vector boson fusion process at $\sqrt{s}=$365 GeV. Furthermore, we explore and evaluate a set of methods for reconstructing tau decays. These techniques are critical for unlocking the full physics potential of the FCC-ee and for improving the understanding of tau-related observables in both Standard Model measurements and New Physics searches. The results obtained significantly enhance the FCC-ee outlook in the H$\toττ$ channel, improving it by at least an order of magnitude compared to the current sensitivity of measurements' performance at the LHC.

hep-ph↗

arXiv2025

Searching for type I seesaw mechanism in a two Heavy Neutral Leptons scenario at FCC-ee

This paper investigates the search for heavy neutral leptons (HNL) in the type I seesaw mechanism at the Future Circular Collider in its $e^+e^-$ stage (FCC-ee), considering a luminosity of 125 ab$^{-1}$ collected at $\sqrt{s}=$91.2 GeV. The study examines two generations of heavy neutral leptons produced in association with Standard Model (SM) neutrinos and decaying to a purely leptonic final state. This theoretical framework can explain neutrino oscillations and other open questions of the SM, providing a broader perspective on the relevance of this experimental search. The analysis is performed using a fast simulation of the IDEA detector concept to study potential HNL interactions at the FCC-ee. The sensitivity contours are obtained from a selection of kinematic variables aimed at improving the signal-to-background ratio for the prompt production case. In the case of long-lived HNLs, the background can be almost fully eliminated by exploiting their displaced decay vertices. The study shows that the FCC-ee has a significant sensitivity to observing these objects in a region of the phase space not accessible by other experiments.

hep-ph↗