Analysis of D+→K-π+e +νe and D+→K -π+μ++νμ semileptonic decays
Physical Review D - Particles, Fields, Gravitation and Cosmology 81:11 (2010)
Abstract:
Using a large sample (≈11800 events) of D+→K -π+e+νe and D+→K -π+μ+νμ decays collected by the CLEO-c detector running at the ψ(3770), we measure the helicity basis form factors free from the assumptions of spectroscopic pole dominance and provide new, accurate measurements of the absolute branching fractions for D +→K̄*0e+νe and D+→K̄*0μ+νμ decays. We find branching fractions which are consistent with previous world averages. Our measured helicity basis form factors are consistent with the spectroscopic pole dominance predictions for the three main helicity basis form factors describing D+→K̄*0 +ν decay. The ability to analyze D+→K -π+μ+νμ allows us to make the first nonparametric measurements of the mass-suppressed form factor. Our result is inconsistent with existing lattice QCD calculations. Finally, we measure the form factor that controls nonresonant s-wave interference with the D +→K̄*0+ν amplitude and search for evidence of possible additional nonresonant d- or f-wave interference with the K̄*0. © 2010 The American Physical Society.Search for the decay J/ψ→γ+invisible
Physical Review D - Particles, Fields, Gravitation and Cosmology 81:9 (2010)
Abstract:
A search for J/ψ radiative decay to weakly interacting neutral final states was performed using the CLEO-c detector at the Cornell Electron Storage Ring. J/ψ events were selected by observing the hadronic decay ψ(2S)→π+π-J/ψ. A total of 3.7×106 J/ψ events were used to study the decay J/ψ→γ+X, where X is a narrow state that is invisible to the detector. No significant signal was observed, and upper limits on the branching fraction were set for masses mX up to 960MeV/c2. The upper limit corresponding to mX=0 is 4.3×10-6 at the 90% confidence level. © 2010 The American Physical Society.Measurement of the W+ W- production cross section and search for anomalous WWγ and WWZ couplings in pp collisions at square root(s)=1.96 TeV.
Phys Rev Lett 104:20 (2010) 201801
Abstract:
This Letter describes the current most precise measurement of the W boson pair production cross section and most sensitive test of anomalous WWγ and WWZ couplings in pp collisions at a center-of-mass energy of 1.96 TeV. The WW candidates are reconstructed from decays containing two charged leptons and two neutrinos. Using data collected by the CDF II detector from 3.6 fb(-1) of integrated luminosity, a total of 654 candidate events are observed with an expected background of 320±47 events. The measured cross section is σ(pp→W+ W- +X)=12.1±0.9(stat)-1.4+1.6(syst) pb, which is in good agreement with the standard model prediction. The same data sample is used to place constraints on anomalous WWγ and WWZ couplings.Measurement of the tt̄ production cross section in pp̄ collisions at √s=1.96TeV using soft electron b-tagging
Physical Review D - Particles, Fields, Gravitation and Cosmology 81:9 (2010)
Abstract:
We present a measurement of the top-quark pair-production cross section in pp̄ collisions at √s=1.96TeV using a data sample corresponding to 1.7fb-1 of integrated luminosity collected with the Collider Detector at Fermilab. We reconstruct tt̄ events in the lepton+jets channel, consisting of eν+jets and μν+jets final states. The dominant background is the production of W bosons in association with multiple jets. To suppress this background, we identify electrons from the semileptonic decay of heavy-flavor jets ("soft electron tags"). From a sample of 2196 candidate events, we obtain 120 tagged events with a background expectation of 51±3 events, corresponding to a cross section of σtt̄=7. 8±2.4(stat)±1.6(syst)±0.5(lumi)pb. We assume a top-quark mass of 175GeV/c2. This is the first measurement of the tt̄ cross section with soft electron tags in run II of the Tevatron. © 2010 The American Physical Society.Search for single top quark production in pp̄ collisions at √s=1.96TeV in the missing transverse energy plus jets topology
Physical Review D - Particles, Fields, Gravitation and Cosmology 81:7 (2010)