Study of $e^{+}e^{-}\to h^{+}h^{-}J/\psi~(h=\pi,~K,~p)$ via initial-state radiation at Belle~II

TL;DR

This study measures cross sections of specific e+e- to h+h-J/psi processes at Belle II, exploring energies from threshold to 7 GeV, and investigates potential new charmonium-like states with no significant structures found.

Contribution

First measurement of e+e- to p p̄ J/psi cross sections via initial-state radiation at Belle II, extending the energy range and searching for new states.

Findings

Cross sections for π+π- J/psi and K+K- J/psi agree with previous results.

First investigation of e+e- to p p̄ J/psi shows no significant structures.

No evidence of new vector charmonium-like states in the studied energy range.

Abstract

Using a data sample of 427.9 fb$^{-1}$ collected by the Belle~II detector at or near the $\Upsilon(4S)$ and $\Upsilon(10753)$ resonances, the cross sections for $e^+e^-\to h^+h^-J/\psi$ $(h=\pi/K/p)$ at center-of-mass energies ranging from 3.8 GeV or the production threshold to 5.5/6.0/7.0 GeV have been measured via initial-state radiation. The cross sections for the processes $e^+e^-\to \pi^+\pi^-J/\psi$ and $e^+e^-\to K^+K^-J/\psi$ are consistent with previously published results. The cross sections for these channels obtained by combining with previous Belle results are also given. The process $e^+e^-\to p\bar p J/\psi$ is investigated for the first time. The yields are small and no significant structure is observed in the cross section versus energy. Searches for vector charmonium-like states in the $h^+h^-J/\psi$ systems, and for associated intermediate states in the $h^{\pm} J/\psi$ systems, are also presented.