Physics with CEBAF at 12 GeV and Future Opportunities

Abstract

We summarize the ongoing scientific program of the 12 GeV Continuous Electron Beam Accelerator Facility (CE-BAF) and give an outlook into future scientific opportunities. The program addresses important topics in nuclear, hadronic, and electroweak physics including nuclear femtography, meson and baryon spectroscopy, quarks and gluons in nuclei, precision tests of the standard model, and dark sector searches. Potential upgrades of CEBAF are considered, such as higher luminosity, polarized and unpolarized positron beams, and doubling the beam energy.

Positron sources: from conventional to advanced accelerator concepts-based colliders

“…CW electron beam with polarization >85% will be used for generation of polarized positrons. Currently, three different electron beam energies are considered: i) 10 MeV, ii) 123 eV and iii) 1090 MeV [97]. 10 MeV option is below the photo-neutron production threshold of most materials, however, suffers from the lowest yield and highest demand on the polarized electron source.…”

Hadron Spectroscopy in Photoproduction

“…First, we briefly review the recent history of the GlueX experiment and the approved future configurations, which cover the expected experimental program to near the end of the current decade. The future prospects for GlueX have been discussed in detail in several recent white papers [27,43]. The main approved GlueX spectroscopy program is separated into two phases.…”

“…A proposed energy, described in Ref. [43] would extend the accessible energy to 20-24 GeV using Fixed Field Alternating Gradient in the existing recirculation arcs with similar luminosity to the existing CEBAF accelerator. Such a facility with up to 24 GeV in photon beam energy will provide new opportunities to study conventional charmonium by significantly extend the energy range of the J/ψ photoproduction cross section measurements described in Sec.…”

“…Figure2: Preliminary GlueX results for the ηπ mass spectra and amplitude analysis for the reactions γp → π 0 ηp (left) and γp → ηπ − ∆ ++ (right) for 0.1 < −t < 0.3 GeV 2 and 8.2 < E γ < 8.8 GeV[43]. The black points give the total measured yield and the colored points give the dominant tensor amplitudes from the amplitude analysis, labeled as L m[35].…”

Sensitivity of Parity-violating Electron Scattering to a Dark Photon

“…Most recently, the potential impact of future PVES experiments on new physics was investigated in the framework of SM effective field theory (SMEFT) [20,21]. The search for physics beyond the SM in PVES is also one of the primary goals of the ongoing scientific program of the 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab [22], especially the SoLID Collaboration [23].…”