Search for two neutrino double electron capture of $^{124}$Xe and $^{126}$Xe in the full exposure of the LUX detector

Author(s): Collaboration, LUX; Akerib, DS; Alsum, S; Araujo, HM; Bai, X; Balajthy, J; Baxter, A; Bernard, EP; Bernstein, A; Biesiadzinski, TP; Boulton, EM; Boxer, B; Bras, P; Burdin, S; Byram, D; Carmona-Benitez, MC; Chan, C; Cutter, JE; Viveiros, L de; Druszkiewicz, E; Fan, A; Fiorucci, S; Gaitskell, RJ; Ghag, C; Gilchriese, MGD; Gwilliam, C; Hall, CR; Haselschwardt, SJ; Hertel, SA; Hogan, DP; Horn, M; Huang, DQ; Ignarra, CM; Jacobsen, RG; Jahangir, O; Ji, W; Kamdin, K; Kazkaz, K; Khaitan, D; Korolkova, EV; Kravits, S; Kudryavtsev, VA; Leason, E; Lenardo, BG; Lesko, KT; Liao, J; Lin, J; Lindote, A; Lopes, MI; Manalaysay, A; Mannino, RL; Marangou, N; Marzioni, MF; McKinsey, DN; Mei, D-M; Moongweluwan, M; Morad, JA; Murphy, A St J; Naylor, A; Nehrkorn, C; Nelson, HN; Neves, F; Nilima, A; Oliver-Mallory, KC; Palladino, KJ; Pease, EK; Riffard, Q; Rischbieter, GRC; Rhyne, C; Rossiter, P; Shaw, S; Shutt, TA; Silva, C; Solmaz, M; Solovov, VN; Sorensen, P; Sumner, TJ; Szydagis, M; Taylor, DJ; Taylor, R; Taylor, WC; Tennyson, BP; Terman, PA; Tiedt, DR; To, WH | Abstract: Two-neutrino double electron capture is a process allowed in the Standard Model of Particle Physics. This rare decay has been observed in $^{78}$Kr, $^{130}$Ba and more recently in $^{124}$Xe. In this publication we report on the search for this process in $^{124}$Xe and $^{126}$Xe using the full exposure of the Large Underground Xenon (LUX) experiment, in a total of of 27769.5~kg-days. No evidence of a signal was observed, allowing us to set 90\% C.L. lower limits for the half-lives of these decays of $2.0\times10^{21}$~years for $^{124}$Xe and $1.9\times10^{21}$~years for $^{126}$Xe.