We present a measurement of the inline image production cross section inline image in inline image collisions at inline image using 5.4 fb-1 of integrated luminosity collected with the D0 detector. ...We consider final states with at least two jets and two leptons (ee, eI14, I14I14), and events with one jet for the eI14 final state as well. The measured cross section is inline image. This result combined with the cross section measurement in the lepton + jets final state yields inline image, which agrees with the standard model expectation. The relative precision of 8% of this measurement is comparable to the precision of the latest theoretical calculations.
We present the first measurement of the inclusive three-jet differential cross section as a function of the invariant mass of the three jets with the largest transverse momenta in an event in inline ...image collisions at inline image. The measurement is made in different rapidity regions and for different jet transverse momentum requirements and is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider. The results are used to test the three-jet matrix elements in perturbative QCD calculations at next-to-leading order in the strong coupling constant. The data allow discrimination between parametrizations of the parton distribution functions of the proton.
We present evidence for diffractive exclusive dijet production with an invariant dijet mass greater than 100 GeV in data collected with the D0 experiment at the Fermilab Tevatron Collider. A ...discriminant based on calorimeter information is used to measure a significant number of events with little energy (typically less than 10 GeV) outside the dijet system, consistent with the diffractive exclusive dijet production topology. The probability for these events to be explained by other dijet production processes is 2x super(10-6, corresponding to a 4.7 standard deviation significance.)
We present a measurement of the ratio of multijet cross sections in p p A= collisions at s = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a data set corresponding to an ...integrated luminosity of 0.7 fb - 1 collected with the D0 detector. The ratio of the inclusive three-jet to two-jet cross sections, R 3 / 2 , has been measured as a function of the jet transverse momenta. The data are compared to QCD predictions in different approximations. Popular tunes of the pythia event generator do not agree with the data, while sherpa provides a reasonable description of the data. A perturbative QCD prediction in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects, gives a good description of the data.
Results of several experiments aimed at exploring the nuclear spatial structure of neutron-rich He and Li isotopes are presented and briefly discussed. The study of the density distributions in these ...nuclei by small-angle proton elastic scattering at intermediate energy is considered in more detail. The performed investigations allow one to obtain information on the total matter distributions, radii of the matter, neutron and proton distributions, effective and internal core sizes, halo sizes, and spatial correlations of the halo nucleons in the studied nuclei.
Density distributions and radii of
6,8He and
8,9,11Li deduced from the 0.7 GeV proton scattering and from the He(Li)+
12C interaction cross sections at 0.8 GeV/u are discussed.
We present measurements of the differential cross section d I / d p T gamma for the associated production of a c-quark jet and an isolated photon with rapidity | y gamma | 15 GeV . The ratio of ...differential cross sections for gamma + c to gamma + b production as a function of p T gamma is also presented. The results are based on data corresponding to an integrated luminosity of 8.7 fb - 1 recorded with the D0 detector at the Fermilab Tevatron p p A= Collider at s = 1.96 TeV . The obtained results are compared to next-to-leading order perturbative QCD calculations using various parton distribution functions, to predictions based on the k T -factorization approach, and to predictions from the sherpa and pythia Monte Carlo event generators.
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