Search for new light gauge bosons in Higgs boson decays to four-lepton final states in pp collisions at s =8 TeV with the ATLAS detector at the LHC
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This paper presents a search for Higgs bosons decaying to four leptons, either electrons or muons, via one or two light exotic gauge bosons Zd, H→ZZd→4 or H→ZdZd→4. The search was performed using pp collision data corresponding to an integrated luminosity of about 20 fb-1 at the center-of-mass energy of s=8 TeV recorded with the ATLAS detector at the Large Hadron Collider. The observed data are well described by the Standard Model prediction. Upper bounds on the branching ratio of H→ZZd→4 and on the kinetic mixing parameter between the Zd and the Standard Model hypercharge gauge boson are set in the range (1-9)×10-5 and (4-17)×10-2 respectively, at 95% confidence level assuming the Standard Model branching ratio of H→ZZ∗→4, for Zd masses between 15 and 55 GeV. Upper bounds on the effective mass mixing parameter between the Z and the Zd are also set using the branching ratio limits in the H→ZZd→4 search, and are in the range (1.5-8.7)×10-4 for 15<mZd<35 GeV. Upper bounds on the branching ratio of H→ZdZd→4 and on the Higgs portal coupling parameter, controlling the strength of the coupling of the Higgs boson to dark vector bosons are set in the range (2-3)×10-5 and (1-10)×10-4 respectively, at 95% confidence level assuming the Standard Model Higgs boson production cross sections, for Zd masses between 15 and 60 GeV.
AuthorsAad, G; Abbott, B; Abdallah, J; Abdinov, O; Aben, R; Abolins, M; Abouzeid, OS; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, BS; Adamczyk, L; Adams, DL; Adelman, J; Adomeit, S; Adye, T; Affolder, AA; Agatonovic-Jovin, T; Aguilar-Saavedra, JA; Ahlen, SP; Ahmadov, F; Aielli, G; Akerstedt, H; Åkesson, TPA; Akimoto, G; Akimov, AV; Alberghi, GL; Albert, J; Albrand, S; Alconada Verzini, MJ; Aleksa, M; Aleksandrov, IN; Alexa, C; Alexander, G; Alexopoulos, T; Alhroob, M; Alimonti, G; Alio, L; Alison, J; Alkire, SP; Allbrooke, BMM; Allport, PP; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Altheimer, A; Alvarez Gonzalez, B; Álvarez Piqueras, D; Alviggi, MG; Amadio, BT; Amako, K; Amaral Coutinho, Y; Amelung, C; Amidei, D; Amor Dos Santos, SP; Amorim, A; Amoroso, S; Amram, N; Amundsen, G; Anastopoulos, C; Ancu, LS; Andari, N; Andeen, T; Anders, CF; Anders, G; Anders, JK; Anderson, KJ; Andreazza, A; Andrei, V; Angelidakis, S; Angelozzi, I; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, AV; Anjos, N; Annovi, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M
- Particle Physics