Search For Higgs Bosons Decaying Into New Spin 0 Or Spin 1 Particles In Four Lepton Final States With The Atlas Detector With 139 Fb 1 Of Pp Collision Data At Square Root S

Search for Higgs Bosons Decaying Into New Spin-0 Or Spin-1 Particles in Four-lepton Final States with the ATLAS Detector with 139 Fb−1 of Pp Collision Data at [square Root]s

Search for New Light Gauge Bosons in Higgs Boson Decays to Four-lepton Final States in Pp Collisions at \(\sqrt{s}

This research presents a search for Higgs bosons decaying to four leptons, either electrons or muons, via one or two light exotic gauge bosons Zd, H 2!ZZd 2!4l or H 2!ZdZd 2!4l. 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 \(\sqrt{s} = 8\) 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 2!ZZd 2!4l 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 2!ZZ* 2!4l, 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 2!ZZd 2!4l search, and are in the range (1.5-8.7) × 10-4 for 15

Search for Higgs Bosons Decaying to Aa in the [mu][mu][tau][tau] Final State in Pp Collisions at [arrow]"

A search for the decay to a pair of new particles of either the 125 GeV Higgs boson (h) or a second charge parity (CP)-even Higgs boson (H) is presented. The data set corresponds to an integrated luminosity of 20.3 fb-1 of pp collisions at [arrow]" = 8 TeV recorded by the ATLAS experiment at the LHC in 2012. The search was done in the context of the next-to-minimal supersymmetric standard model, in which the new particles are the lightest neutral pseudoscalar Higgs bosons (a). One of the two a bosons is required to decay to two muons while the other is required to decay to two [tau] leptons. No significant excess is observed above the expected backgrounds in the dimuon invariant mass range from 3.7 to 50 GeV. Upper limits are placed on the production of h 2!aa relative to the standard model gg 2!h production, assuming no coupling of the a boson to quarks. The most stringent limit is placed at 3.5% for ma = 3.75 GeV. The upper limits are also placed on the production cross section of H 2!aa from 2.33 to 0.72 pb, for fixed ma = 5 GeV with mH ranging from 100 to 500 GeV.