Date

Measurement of the Underlying Event Activity in Proton-Proton Collisions at 0.9 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M. ; Tumasyan, Armen ; et al.
Eur.Phys.J.C 70 (2010) 555-572, 2010.
Inspire Record 857644 DOI 10.17182/hepdata.55126

A measurement of the underlying activity in scattering processes with transverse momentum scale in the GeV region is performed in proton-proton collisions at sqrt(s) = 0.9 TeV, using data collected by the CMS experiment at the LHC. Charged hadron production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged hadrons with pseudorapidity eta < 2, p_T > 0.5 GeV/c, and azimuthal direction transverse to that of the leading object.

7 data tables

Average multiplicity of charged particles per unit of pseudorapidity as a function of pseudorapidity for events with leading track-jet transverse momenta > 1 and > 3 GeV. Statistical errors only.

Average scalar sum of the transverse momenta of charged particles per unit of pseusdorapidity and per radian as a function of DELTA(PHI) for events with leading track-jet transverse momenta > 1 and > 2 GeV. Statistical errors only. Typical systematic error of 1.8 PCT at a leading track-jet PT of 3.5 GeV.

The average multiplicity and average scalar sum of transverse momenta of charge particles per unit of pseudorapidity and per radian as a function of the leading track transverse momenta. Statistical errors only. Typical systematic error of 1.8 PCT at a leading track-jet PT of 3.5 GeV.

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Measurement of $Z / \gamma^\ast +jet+X$ angular distributions in $p \bar{p}$ collisions at $\sqrt{s}=1.96$ TeV

The D0 collaboration Abazov, Victor Mukhamedovich ; Abbott, Braden Keim ; Abolins, Maris A. ; et al.
Phys.Lett.B 682 (2010) 370-380, 2010.
Inspire Record 826756 DOI 10.17182/hepdata.52513

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.

12 data tables

Differential cross section in bins of PHI(P=3)-PHI(P=4) for Z/GAMMA* transverse momentum > 25 GeV.

Differential cross section in bins of PHI(P=3)-PHI(P=4) for Z/GAMMA* transverse momentum > 45 GeV.

Differential cross section in bins of ABS(YRAP(P=3)-YRAP(P=4)) for Z/GAMMA* transverse momentum > 25 GeV.

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