# Investigation of the background in coherent $J/\psi$ production at the EIC

### Submission summary

 As Contributors: Wan Chang Preprint link: scipost_202108_00003v2 Date accepted: 2022-03-31 Date submitted: 2022-03-03 18:08 Submitted by: Chang, Wan Submitted to: SciPost Physics Proceedings Proceedings issue: DIS2021 Academic field: Physics Specialties: High-Energy Physics - Experiment Approach: Experimental

### Abstract

Understanding fundamental properties of nucleons and nuclei are among the most important scientific goals of the next-generation machine, the Electron-Ion Collider (EIC). With the unprecedented versatility provided by the EIC, it will provide answers to many standing puzzles and open questions in modern nuclear physics. One of the golden measurements at the EIC is coherent vector meson production in electron-nucleus (eA) scattering in order to obtain the spatial gluon density distribution in heavy nuclei. This requires the experiment to overcome an overwhelmingly large background arising from the incoherent diffractive production, where the nucleus mostly breaks up into fragments of particles in the far-forward direction close to the hadron beam rapidity. In this talk, we systematically study the rejection of incoherent $J/\psi$ production by vetoing products from the nuclear breakup - protons, neutrons, and photons, which is modeled with the BeAGLE event generator and the most up-to-date EIC Far-forward Interaction Region design.

###### Current status:
Publication decision taken: accept

Editorial decision: For Journal SciPost Physics Proceedings: Publish
(status: Editorial decision fixed and (if required) accepted by authors)

### List of changes

I have rephrased the sentence at the end of page.3 as follows,

Figure 1 shows, that the vetoing on protons, neutrons, and photons are all important and contribute to a significant reduction of the background. After veto.7, the residual contribution is about 1--10% of the total events, depending on the value of |t|.
->
There are ~94\% of these incoherent events that have at least one neutron produced, and ZDC has a good acceptance for neutrons. Therefore, only less than 10% of events survived after veto.2. Because of the rigidity change, the RP and B0 made an insignificant contribution for proton measurements, while most of the protons within small scattering angle are detected by OMD. Figure 1 shows that after the vetoing on neutrons, protons, and photons, the residual contribution is about 1--10% of the total events, depending on the value of |t|.

### Submission & Refereeing History

Resubmission scipost_202108_00003v2 on 3 March 2022
Submission scipost_202108_00003v1 on 2 August 2021