Letter of Intent: Open Charm at JLab with the sPHENIX MAPS tracker

TL;DR

This paper proposes an open-charm physics program at JLab using the CLAS12 detector with an integrated sPHENIX MAPS tracker to measure $D$ mesons, aiming to understand charm production mechanisms and gluon structure.

Contribution

It introduces the integration of the sPHENIX MVTX tracker with CLAS12 for open-charm measurements, a novel approach to enhance secondary-vertex detection capabilities.

Findings

Feasibility estimates suggest potential for open-charm measurements at threshold.

Simulation studies support the technical integration of MVTX with CLAS12.

Preliminary rate estimates indicate promising prospects for future experiments.

Abstract

We propose a physics program at JLab with CLAS12 focusing on open-charm measurements, aiming to complement and expand current studies of $J/\psi$ at (sub) threshold. This program will aid us in elucidating the $J/\psi$ production mechanisms, which is crucial for interpreting data in terms of gluon form factors and offer potential insights into the intrinsic charm hypothesis and cold-nuclear matter effects. We discuss the technical feasibility of integrating the sPHENIX monolithic-active-pixel sensor (MAPS) tracker, known as MVTX, with the CLAS12 detector. The sPHENIX MTVX would support an open-charm program by providing excellent secondary-vertex performance for tagging $D$ mesons. We study the kinematics of $\gamma p \to \bar{D}^{0}\Lambda_{c}$ through phase-space simulations and estimate rates for the tagged quasi-photoproduction regime available with the CLAS12 forward tagger. While open-charm cross-sections at threshold remain uncertain, various predictions suggest that these measurements could be feasible when combined with conservative estimates of detector acceptance and luminosity. These preliminary estimates motivate detailed Geant detector simulations of signals and backgrounds, along with thorough technical assessments of operating conditions, to further explore the feasibility of these measurements in future dedicated CLAS12 experiments at JLab.