Direct production of χc1 at BESIII

Yuping Guo,A Bondar,S Eidelman

doi:10.1051/epjconf/201920206009

Abstract

The production of resonances in electron-positron annihilation has only been observed for states with quantum numbers JPC = 1−−, while C = +1 resonances appear only among the decay products. The direct production of the 1++ states could happen through two-photon or neutral current. Due to the smallness of the production rate, this process has never been verified experimentally. With the high luminosity and good performance of the BESIII experiment, a search of the direct production of the 1++ state in charmonium region, χc1, is undergoing with dedicated data samples around the χc1 mass. An overview of the data analysis will be presented.

Highlights

IntroductionThe contribution from two-photon annihilation dominates the production rate [1]
Up to now, only the production of resonances with the quantum numbers JPC = 1−− has been observed in e+e− annihilation through a virtual photon, states with other quantum numbers are appeared only among the decay products
The electronic width of χcJ has been revisited within the Vector Dominance Model (VDM) [3] and the NRQCD [4] framework, the values from the new estimations are at 0.1 eV level

Summary

Introduction

The contribution from two-photon annihilation dominates the production rate [1]. The production rate, which is proportional to the electronic width, has already been calculated a long time ago [1, 2]. The lower limit of the electronic width of χc is calculated to be Γee > 0.044 eV, while in Vector Dominance Model (VDM), the prediction is Γee = 0.46 eV [1]. The study focuses on the radiative decay of χcJ to γJ/ψ, followed by J/ψ → μ+μ−, and its interference with the continuum background process, e+e− → γISRμ+μ−, where the photon is from radiative corrections. With the high luminosity and excellent performance of the Beijing Electron Positron Collider (BEPCII) and the BESIII detector [6, 7], a study has been launched at the BESIII experiment to search for the direct production of χc

The BEPCII and BESIII detector

The data samples

Analysis strategy

Event selection and number of events estimation

Conclusion