Search for flavor-changing-neutral-current D meson decays
Physical Review Letters 100:10 (2008)
Abstract:
We study the flavor-changing-neutral-current process c→uμ+μ- using 1.3fb-1 of pp̄ collisions at s=1.96TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the charged-current mediated Ds+ and D+→ π+→μ+μ-π+ final states with significance greater than 4 standard deviations above background for the D+ state. We search for the continuum neutral-current decay of D+→π+μ+μ- in the dimuon invariant mass spectrum away from the resonance. We see no evidence of signal above background and set a limit of B(D+→π+μ+μ-)<3.9×10-6 at the 90% C.L. This limit places the most stringent constraint on new phenomena in the c→uμ+μ- transition. © 2008 The American Physical Society.Search for flavor-changing-neutral-current d meson decays.
Phys Rev Lett 100:10 (2008) 101801
Abstract:
We study the flavor-changing-neutral-current process c-->u micro(+) micro(-) using 1.3 fb(-1) of pp[over ] collisions at square root s = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the charged-current mediated D(s)(+) and D(+)-->phipi(+) --> micro(+)micro(-)pi(+) final states with significance greater than 4 standard deviations above background for the D(+) state. We search for the continuum neutral-current decay of D(+)-->pi(+) micro(+) micro(-) in the dimuon invariant mass spectrum away from the phi resonance. We see no evidence of signal above background and set a limit of B(D(+) --> pi(+) micro(+) micro(-))<3.9 x 10(-6) at the 90% C.L. This limit places the most stringent constraint on new phenomena in the c--> u micro(+) micro(-) transition.Limits on the production of narrow tt̄ resonances in pp̄ collisions at s=1.96TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 77:5 (2008)
Abstract:
We search for evidence of resonant top quark pair production in 955 pb-1 of pp̄ collisions at s=1.96TeV recorded with the CDF II detector at the Fermilab Tevatron. For fully reconstructed candidate tt̄ events triggered on leptons with large transverse momentum and containing at least one identified b-quark jet, we compare the invariant mass spectrum of tt̄ pairs to the expected superposition of standard model tt̄, non-tt̄ backgrounds, and a simple resonance model based on a sequential Z′ boson. We establish upper limits for σ(pp̄→Z′) ·Br(Z′→tt̄) in the Z′ mass interval from 450GeV/c2 to 900GeV/c2. A topcolor leptophobic Z′ is ruled out below 720GeV/c2, and the cross section of any narrow Z′-like state decaying to tt̄ is found to be less than 0.64 pb at 95% C.L. for MZ′ above 700GeV/c2. © 2008 The American Physical Society.Measurement of inclusive jet cross sections in Z/γ*(→e+e-) +jets production in pp̄ collisions at s=1.96 TeV
Physical Review Letters 100:10 (2008)
Abstract:
Inclusive jet cross sections in Z/γ* events, with Z/γ* decaying into an electron-positron pair, are measured as a function of jet transverse momentum and jet multiplicity in pp̄ collisions at s=1.96 TeV with the upgraded Collider Detector at Fermilab in run II, based on an integrated luminosity of 1.7 fb-1. The measurements cover the rapidity region |yjet|<2.1 and the transverse momentum range pTjet>30GeV/c. Next-to-leading order perturbative QCD predictions are in good agreement with the measured cross sections. © 2008 The American Physical Society.Measurement of the shape of the boson-transverse momentum distribution in pp̄→Z/γ*→e+e-+X events produced at s=1.96TeV
Physical Review Letters 100:10 (2008)