Search for excited electrons in pp̄ collisions at s=1.96TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 77:9 (2008)
Abstract:
We present the results of a search for the production of an excited state of the electron, e*, in proton-antiproton collisions at s=1.96TeV. The data were collected with the D0 experiment at the Fermilab Tevatron Collider and correspond to an integrated luminosity of approximately 1fb-1. We search for e* in the process pp̄→e*e, with the e* subsequently decaying to an electron plus photon. No excess above the standard model background is observed. Interpreting our data in the context of a model that describes e* production by four-fermion contact interactions and e* decay via electroweak processes, we set 95% C.L. upper limits on the production cross section ranging from 8.9 to 27 fb, depending on the mass of the excited electron. Choosing the scale for contact interactions to be Λ=1TeV, excited electron masses below 756 GeV are excluded at the 95% C.L. © 2008 The American Physical Society.Measurement of the forward-backward charge asymmetry in top-quark pair production.
Phys Rev Lett 100:14 (2008) 142002
Abstract:
We present the first measurement of the integrated forward-backward charge asymmetry in top-quark-top-antiquark pair (tt) production in proton-antiproton (pp) collisions in the lepton+jets final state. Using a b-jet tagging algorithm and kinematic reconstruction assuming tt + X production and decay, a sample of 0.9 fb(-1) of data, collected by the D0 experiment at the Fermilab Tevatron Collider, is used to measure the asymmetry for different jet multiplicities. The result is also used to set upper limits on tt+X production via a Z' resonance.Measurement of the forward-backward charge asymmetry in top-quark pair production
Physical Review Letters 100:14 (2008)
Abstract:
We present the first measurement of the integrated forward-backward charge asymmetry in top-quark "top-antiquark pair (tt) production in proton-antiproton (pp) collisions in the lepton+jets final state. Using a b-jet tagging algorithm and kinematic reconstruction assuming tt+X production and decay, a sample of 0.9 fb-1 of data, collected by the D0 experiment at the Fermilab Tevatron Collider, is used to measure the asymmetry for different jet multiplicities. The result is also used to set upper limits on tt+X production via a Z resonance. © 2008 The American Physical Society.Search for ZZ and Zgamma* production in pp[over ] collisions at square root s=1.96 TeV and limits on anomalous ZZZ and ZZgamma* couplings.
Phys Rev Lett 100:13 (2008) 131801
Abstract:
We present a study of micro micro micro micro, eeee, and micro micro ee events using 1 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron pp[over ] Collider at square root s=1.96 TeV. Requiring the lepton pair masses to be greater than 30 GeV, we observe one event, consistent with the expected background of 0.13+/-0.03 events and with the predicted standard model ZZ and Zgamma* production of 1.71+/-0.15 events. We set an upper limit on the ZZ and Zgamma* cross section of 4.4 pb at the 95% C.L. We also derive limits on anomalous neutral trilinear ZZZ and ZZgamma* gauge couplings. The one-parameter 95% C.L. coupling limits with a form-factor scale Lambda=1.2 TeV are -0.28Erratum: Measurement of the WW production cross section in pp̄ collisions at s=1.96TeV (Physical Review Letters (2005) 94 (151801))
Physical Review Letters 100:13 (2008)