Observation of an Unusual Upward-Going Cosmic-Ray-like Event in the Third Flight of ANITA

• Main Authors: Gorham, PW, Rotter, B, Allison, P, Banerjee, O, Batten, L, Beatty, JJ, Bechtol, K, Belov, K, Besson, DZ, Binns, WR, Bugaev, V, Cao, P, Chen, CC, Chen, CH, Chen, P, Clem, JM, Connolly, A, Cremonesi, L, Dailey, B, Deaconu, C, Dowkontt, PF, Fox, BD, Gordon, JWH, Hast, C, Hill, B, Hughes, K, Huang, JJ, Hupe, R, Israel, MH, Javaid, A, Lam, J, Liewer, KM, Lin, SY, Liu, TC, Ludwig, A, Macchiarulo, L, Matsuno, S, Miki, C, Mulrey, K, Nam, J, Naudet, CJ, Nichol, RJ, Novikov, A, Oberla, E, Olmedo, M, Prechelt, R, Prohira, S, Rauch, BF, Roberts, JM, Romero-Wolf, A, Russell, JW, Saltzberg, D, Seckel, D, Schoorlemmer, H, Shiao, J, Stafford, S, Stockham, J, Stockham, M, Strutt, B, Varner, GS, Vieregg, AG, Wang, SH, Wissel, SA
• Format: Article in Journal/Newspaper
• Language: English
• Published: AMER PHYSICAL SOC 2018
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: https://discovery.ucl.ac.uk/id/eprint/10061093/1/PhysRevLett.121.161102.pdf; https://discovery.ucl.ac.uk/id/eprint/10061093/

We report on an upward traveling, radio-detected cosmic-ray-like impulsive event with characteristics closely matching an extensive air shower. This event, observed in the third flight of the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload, is consistent with a similar event reported in a previous flight. These events could be produced by the atmospheric decay of an upward-propagating τ lepton produced by a ν τ interaction, although their relatively steep arrival angles create tension with the standard model neutrino cross section. Each of the two events have a posteriori background estimates of ≲ 10 − 2 events. If these are generated by τ -lepton decay, then either the charged-current ν τ cross section is suppressed at EeV energies, or the events arise at moments when the peak flux of a transient neutrino source was much larger than the typical expected cosmogenic background neutrinos