PT Journal
AU ATLAS Collaboration (Aad, Gea
   Alvarez Piqueras, D
   Barranco Navarro, L
   Cabrera Urban, S
   Castillo Gimenez, V
   Cerda Alberich, L
   Costa, MJ
   Fernandez Martinez, P
   Ferrer, A
   Fiorini, L
   Fuster, J
   Garcia, C
   Garcia Navarro, JE
   Gonzalez de la Hoz, S
   Hernandez Jimenez, Y
   Higon-Rodriguez, E
   Irles Quiles, A
   Jimenez Pena, J
   King, M
   Lacasta, C
   Lacuesta, VR
   Mamuzic, J
   Marti-Garcia, S
   Mitsou, VA
   Pedraza Lopez, S
   Rodriguez Rodriguez, D
   Romero Adam, E
   Ros, E
   Salt, J
   Sanchez Martinez, V
   Soldevila, U
   Sanchez, J
   Valero, A
   Valls Ferrer, JA
   Vos, M
TI Measurements of Z gamma and Z gamma gamma production in pp collisions at root s=8 TeV with the ATLAS detector
SO Physical Review D
JI Phys. Rev. D
PY 2016
BP 112002
EP 41pp
VL 93
IS 11
DI 10.1103/PhysRevD.93.112002
LA English
AB The production of Z bosons with one or two isolated high-energy photons is studied using pp collisions at root s = 8 TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb(-1) collected by the ATLAS detector during the 2012 LHC data taking. The Z gamma and Z gamma gamma production cross sections are measured with leptonic (e(+) e(-), mu(+) mu(-), nu(nu) over bar) decays of the Z boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative Z-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy E-T > 250 GeV from l(+) l(-) gamma events and with E-T > 400 GeV from nu(nu) over bar gamma events are used to search for anomalous triple gauge-boson couplings ZZ gamma and Z gamma gamma. The yields of events with diphoton invariant mass m(gamma gamma) > 200 GeV from l(+) l(-) gamma gamma events and with m(gamma gamma) > 300 GeV from nu(nu) over bar gamma gamma events are used to search for anomalous quartic gauge-boson couplings ZZ gamma gamma and Z gamma gamma gamma. No deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings.
ER