The Two-Photon Exchange Experiment at DESY

• DOI: 10.48550/arxiv.2307.13330
• Publication Date: 2023-01-01
• Authors: Ricardo Alarcón; R. Beck; J. C. Bernauer; M. Broering; A. Christopher; E. W. Cline; S. Dhital; B. Dongwi; I. Fernando; M. Finger; M. Finger; I. Friščić; T. Gautam; G. N. Grauvogel; D. K. Hasell; O. Hen; T. Horn; E. Ihloff; R. Johnston; J. Kelsey; M. Köhl; T. Kutz; I. Lavrukhin; S. Lee; W. Lorenzon; S. Lunkenheimer; F. Maas; R. G. Milner; P. Moran; J. Nazeer; T. Patel; M. Rathnayake; R. Raymond; R. P. Redwine; A. Schmidt; U. Schneekloth; D. Sokhan; M. Suresh; C. Vidal; Z. Yang
• Keywords: DESY

We propose a new measurement of the ratio positron-proton to electron-proton elastic scattering at DESY. The purpose is determine contributions beyond single-photon exchange, which are essential for Quantum Electrodynamic (QED) description most fundamental process in hadronic physics. By utilizing 20 cm long liquid hydrogen target conjunction with extracted beam from DESY synchrotron, we can achieve an average luminosity $2.12\times10^{35}$ cm$^{-2}\cdot$s$^{-1}\cdot$sr$^{-1}$ ($\approx200$ times achieved by OLYMPUS). proposed TPEX experiment entails commissioning run 2 GeV, followed measurements 3 thereby providing data up $Q^2=4.6$ (GeV/$c$)$^2$ (twice range current measurements). present and discuss experimental setup, plan, expectations.