# Some hadronic parameters of charmonia in $\boldsymbol{N_{\text{f}}=2}$ lattice QCD

## TL;DR

This paper presents a lattice QCD study of decay constants for charmonium states, providing insights into their properties and potential implications for beyond Standard Model physics.

## Contribution

It reports new lattice QCD calculations of decay constants for $ ext{N}_f=2$ charmonium states, including excited states, which were previously less understood.

## Key findings

- Calculated decay constants for $ ext{N}_f=2$ $ ext{J}/ ext{psi}$ and $ ext{$ ext{eta}_c$}$.
- Examined properties of first radial excitations $ ext{$ ext{eta}_c(2S)$}$ and $ ext{$ ext{psi}(2S)$}$.
- Results can constrain new physics scenarios involving light CP-odd states.

## Abstract

The phenomenology of leptonic decays of quarkonia holds many interesting features: for instance, it can establish constraints on scenarios beyond the Standard Model with the Higgs sector enriched by a light CP-odd state. In the following paper, we report on a two-flavor lattice QCD study of the $\eta_c$ and $J/\psi$ decay constants, $f_{\eta_c}$ and $f_{J\psi}$. We also examine some properties of the first radial excitation $\eta_c(2S)$ and $\psi(2S)$.