A new decay mode of higher charmonium

TL;DR

This paper investigates the decay widths of excited vector charmonium states around 4.6 GeV into Lambda_c anti-Lambda_c pairs, suggesting the Y(4660) could be an S-wave charmonium state based on decay width calculations.

Contribution

It provides the first detailed calculation of Lambda_c anti-Lambda_c decay widths for higher charmonium states using the quark pair creation model, offering insights into the nature of Y(4660).

Findings

Decay widths for psi(4S, 5S, 6S) can reach several MeV.

Decay widths for psi(3D, 4D, 5D) are less than one MeV.

Y(4660) is likely an S-wave charmonium state.

Abstract

We calculate the $\Lambda_c\bar{\Lambda}_c$ partial decay width of the excited vector charmonium states around 4.6 GeV with the quark pair creation model. We find that the partial decay width of the $\Lambda_c\bar{\Lambda}_c$ mode can reach up to several MeV for $\psi(4S,~5S,~6S)$. In contrast, the partial $\Lambda_c\bar{\Lambda}_c$ decay width of the states $\psi(3D,~4D,~5D)$ is less than one MeV. If the enhancement $Y(4630)$ reported by the Belle Collaboration in $\Lambda_c\bar{\Lambda}_c$ invariant-mass distribution is the same structure as $Y(4660)$, the $Y(4660)$ resonance is most likely to be a $S$-wave charmonium state.