Using the Primakoff formalism, we have extracted the radiative decay width of the A + 2 (1310) produced in coherent interactions of 200 GeV/ c π + mesons in nuclear targets. The width obtained is 295 ± 60 keV, a value consistent with quark-model predictions.
Using the Primakoff formalism, we have extracted the radiative decay width of the K ∗+ (1430) produced in coherent interactions of 200 GeV/ c K + mesons in nuclear targets. The width obtained is 240 ± 45 keV, a value reasonably consistent with quark-model predictions.
Coherent production of Kπ systems observed in the excitation of 200-GeV/c positive kaons on nuclear targets has been analyzed, including both electromagnetic and strong contributions, to yield a new value for the radiative width for the process K*+(890)→K+γ of 51 ± 5 keV.
The upgraded Collider Detector at Fermilab (CDF II) has a high bandwidth available for track based triggers. This capability in conjunction with the unprecedented integrated luminosity in excess of 1 fb −1 enables detailed studies of charm hadron production. CDF is now releasing first measurements of the prompt charm meson pair cross sections, which give access to QCD mechanisms by which charm quarks are produced in proton anti-proton collisions. Recent results on the spin alignment of J/ψ and ψ(2S) as well as on the relative production of the χc1(P1) and χc2(1P) challenge our understanding of the fragmentation of charm quarks into charmonium states.
The differential cross section for elastic antiproton—proton scattering at s =1.8 TeV has been measured over the t range 0.034⩽| t |⩽0.65 (GeV/ c ) 2 . A logarithmic slope parameter, B , of 16.3±0.3 (GeV/ c ) −2 is obtained. In contrast to lower energy experiments, no change in slope is observed over this t range.
We have measured the cross section for production of ψ and ψ′ in p¯ and π− interactions with Be, Cu, and W targets in experiment E537 at Fermilab. The measurements were performed at 125 GeV/c using a forward dimuon spectrometer in a closed geometry configuration. The gluon structure functions of the p¯ and π− have been extracted from the measured dσdxF spectra of the produced ψ's. From the p¯W data we obtain, for p¯, xG(x)=(2.15±0.7)[1−x](6.83±0.5)[1+(5.85±0.95)x]. In the π− case, we obtain, from the W and the Be data separately, xG(x)=(1.49±0.03)[1−x](1.98±0.06) (for π−W), xG(x)=(1.10±0.10)[1−x](1.20±0.20) (for π−Be).
The ArgoNeuT collaboration presents measurements of inclusive muon neutrino and antineutrino charged current differential cross sections on argon in the Fermilab NuMI beam operating in the low energy antineutrino mode. The results are reported in terms of outgoing muon angle and momentum at a mean neutrino energy of 9.6 GeV (neutrinos) and 3.6 GeV (antineutrinos), in the range $0^\circ < \theta_\mu < 36^\circ$ and $0 < p_\mu < 25$ GeV/$c$, for both neutrinos and antineutrinos.
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We have studied D* production mechanisms using data from a photoproduction experiment at the Fermilab Tagged Photon Spectrometer. A large sample of charged D*’s was selected via the clean signature of the cascade decay D*→D0π+ and subsequently D0→K−π+ or D0→K−π+π0. The cross section for the process γp→(D*++anything)p at an average energy of 105 GeV was measured to be 88±32 nb. Only (11±7)% of D*’s were found to be consistent with being accompanied solely by a D¯* or a D¯; the remaining events contain additional particles. The distribution of the production angle of the D* in the photon-fragmentation-system center of mass is strongly anisotropic and consistent with the form f(θ*)=cos4θ*. We set a limit on the associated-production-process cross section σ(γp→(D¯*−+anything)Λc) x)<60 nb (90% C.L.).
The dijet invariant mass distribution has been measured in the region between 120 and 1000 GeV/c2, in 1.8-TeV pp¯ collisions. The data sample was collected with the Collider Detector at Fermilab (CDF). Data are compared to leading order (LO) and next-to-leading order (NLO) QCD calculations using two different clustering cone radii R in the jet definition. A quantitative test shows good agreement of data with the LO and NLO QCD predictions for a cone of R=1. The test using a cone of R=0.7 shows less agreement. The NLO calculation shows an improvement compared to LO in reproducing the shape of the spectrum for both radii, and approximately predicts the cone size dependence of the cross section.
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