Search for a new gauge boson in electron-nucleus fixed-target scattering by the APEX experiment

• Published in: Physical review letters 2011-11, Vol.107 (19), p.191804-191804, Article 191804
• Main Authors: Abrahamyan, S, Ahmed, Z, Allada, K, Anez, D, Averett, T, Barbieri, A, Bartlett, K, Beacham, J, Bono, J, Boyce, J R, Brindza, P, Camsonne, A, Cranmer, K, Dalton, M M, de Jager, C W, Donaghy, J, Essig, R, Field, C, Folts, E, Gasparian, A, Goeckner-Wald, N, Gomez, J, Graham, M, Hansen, J-O, Higinbotham, D W, Holmstrom, T, Huang, J, Iqbal, S, Jaros, J, Jensen, E, Kelleher, A, Khandaker, M, LeRose, J J, Lindgren, R, Liyanage, N, Long, E, Mammei, J, Markowitz, P, Maruyama, T, Maxwell, V, Mayilyan, S, McDonald, J, Michaels, R, Moffeit, K, Nelyubin, V, Odian, A, Oriunno, M, Partridge, R, Paolone, M, Piasetzky, E, Pomerantz, I, Qiang, Y, Riordan, S, Roblin, Y, Sawatzky, B, Schuster, P, Segal, J, Selvy, L, Shahinyan, A, Subedi, R, Sulkosky, V, Stepanyan, S, Toro, N, Walz, D, Wojtsekhowski, B, Zhang, J
• Format: Article
• Language: English
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.107.191804

We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α' to electrons. Such a particle A' can be produced in electron-nucleus fixed-target scattering and then decay to an e + e- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175-250 MeV, found no evidence for an A'→ e+ e- reaction, and set an upper limit of α'/α ~/= 10(-6). Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.