We have measured charged-particle production in neutron-nucleus collisions at high energy. Data on positive and negative particles produced in nuclei [ranging in atomic number (A) from beryllium to lead] are presented for essentially the full forward hemisphere of the center-of-mass system. A rough pion-proton separation is achieved for the positive spectra. Fits of the form Aα to the cross sections are presented as functions of transverse momentum, longitudinal momentum, rapidity, and pseudorapidity. It is found that α changes from ∼0.85 to ∼0.60 for laboratory rapidities ranging from 4 to 8. Trends in the data differ markedly when examined in terms of pseudorapidity rather than rapidity. Qualitatively, the major features of our data can be understood in terms of current particle-production models.

The inclusive b-jet production cross section in pp collisions at a center-of-mass energy of 7 TeV is measured using data collected by the CMS experiment at the LHC. The cross section is presented as a function of the jet transverse momentum in the range 18 < pT < 200 GeV for several rapidity intervals. The results are also given as the ratio of the b-jet production cross section to the inclusive jet production cross section. The measurement is performed with two different analyses, which differ in their trigger selection and b-jet identification: a jet analysis that selects events with a b jet using a sample corresponding to an integrated luminosity of 34 inverse picobarns, and a muon analysis requiring a b jet with a muon based on an integrated luminosity of 3 inverse picobarns. In both approaches the b jets are identified by requiring a secondary vertex. The results from the two methods are in agreement with each other and with next-to-leading order calculations, as well as with predictions based on the PYTHIA event generator.

The transverse-momentum spectra of lambdas (Λ0, Λ¯0) produced in the central region has been measured in p¯p collisions at s=1.8 TeV at the Fermilab Collider. We find that the average transverse momentum of the lambdas increases more rapidly with center-of-mass energy than that of charged particles, and the ratio of lambdas to charged particles increases as a function of center-of-mass energy.

We present the first measurements at a hadron collider of differential cross sections for Z+jet+X production in delta phi(Z, jet), |delta y(Z, jet)| and |y_boost(Z, jet)|. Vector boson production in association with jets is an excellent probe of QCD and constitutes the main background to many small cross section processes, such as associated Higgs production. These measurements are crucial tests of the predictions of perturbative QCD and current event generators, which have varied success in describing the data. Using these measurements as inputs in tuning event generators will increase the experimental sensitivity to rare signals.

We report on a CDF measurement of the total cross section and rapidity distribution, $d\sigma/dy$, for $q\bar{q}\to \gamma^{*}/Z\to e^{+}e^{-}$ events in the $Z$ boson mass region ($66<M_{ee}<116$GeV/c$^2$) produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$TeV with 2.1fb$^{-1}$ of integrated luminosity. The measured cross section of $257\pm16$pb and $d\sigma/dy$ distribution are compared with Next-to-Leading-Order(NLO) and Next-to-Next-to-Leading-Order(NNLO) QCD theory predictions with CTEQ and MRST/MSTW parton distribution functions (PDFs). There is good agreement between the experimental total cross section and $d\sigma/dy$ measurements with theoretical calculations with the most recent NNLO PDFs.

Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at sqrt(s) = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 inverse picobarns. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda = 5.6 TeV (6.7 TeV) for destructive (constructive) interference is obtained at the 95% confidence level.

We report on the first measurement of the rapidity distribution dsigma/dy over nearly the entire kinematic region of rapidity for e^+e^- pairs in the Z-boson region of 66<M_{ee}<116 GeV/c^2 and at higher mass M_{ee}>116 GeV/c^2. The data sample consists of 108 pb^{-1} of ppbar collisions at \sqrt{s}=1.8 TeV taken by the Collider Detector at Fermilab during 1992--1995. The total cross section in the $Z$-boson region is measured to be 252 +- 11 pb. The measured total cross section and d\sigma/dy are compared with quantum chromodynamics calculations in leading and higher orders.

The production of top quark-antiquark pair events in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is studied as a function of the transverse momentum and absolute value of the rapidity of the top quarks as well as of the invariant mass of the $t\bar{t}$ pair. We select events containing an isolated lepton, a large imbalance in transverse momentum, and four or more jets with at least one jet identified to originate from a $b$ quark. The data sample corresponds to 9.7 fb$^{-1}$ of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Observed differential cross sections are consistent with standard model predictions.

We present new measurements of differential cross sections for Z/gamma*(->mumu)+jet+X production in a 1 fb-1 data sample collected with the D0 detector in proton anti-proton collisions at sqrt{s}=1.96 TeV. Results include the first measurements differential in the Z/gamma* transverse momentum and rapidity, as well as new measurements differential in the leading jet transverse momentum and rapidity. Next-to-leading order perturbative QCD predictions are compared to the measurements, and reasonable agreement is observed, except in the region of low Z/gamma* transverse momentum. Predictions from two event generators based on matrix elements and parton showers, and one pure parton shower event generator are also compared to the measurements. These show significant overall normalization differences to the data and have varied success in describing the shape of the distributions.

The production of a Z boson, decaying to two charged leptons, in association with jets in proton-proton collisions at a centre-of-mass energy of 13 TeV is measured. Data recorded with the CMS detector at the LHC are used that correspond to an integrated luminosity of 2.19 fb$^{-1}$. The cross section is measured as a function of the jet multiplicity and its dependence on the transverse momentum of the Z boson, the jet kinematic variables (transverse momentum and rapidity), the scalar sum of the jet momenta, which quantifies the hadronic activity, and the balance in transverse momentum between the reconstructed jet recoil and the Z boson. The measurements are compared with predictions from four different calculations. The first two merge matrix elements with different parton multiplicities in the final state and parton showering, one of which includes one-loop corrections. The third is a fixed-order calculation with next-to-next-to-leading order accuracy for the process with a Z boson and one parton in the final state. The fourth combines the fully differential next-to-next-to-leading order calculation with next-to-next-to-leading logarithm resummation and parton showering.