The first prompt photon measurement from the CDF experiment at the Fermilab pp¯ Collider is presented. Two independent methods are used to measure the cross section: one for high transverse momentum (PT) and one for lower PT. Comparisons to various theoretical calculations are shown. The cross section agrees qualitatively with QCD calculations but has a steeper slope at low PT.
Cross section using profile method and an isolation cut of 2 GeV in a cone around the photon. There is an additional 27 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
Cross section using conversion method and an isolation cut of 2 GeV in a cone around the photon. There is an additional +32,-46 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
Cross section using profile method and an isolation cut of 15 pct of the photon PT in a cone around the photon. There is an additional 29 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
A prompt photon cross section measurement from the Collider Detector at Fermilab experiment is presented. Detector and trigger upgrades, as well as 6 times the integrated luminosity compared with our previous publication, have contributed to a much more precise measurement and extended PT range. As before, QCD calculations agree qualitatively with the measured cross section, but the data has a steeper slope than the calculations.
Note that the sytematic uncertainties are approximately 100 pct correlated bin to bin.
The properties of two-, three-, four-, five-, and six-jet events with multijet masses >600 GeV /c2 are compared with QCD predictions. The shapes of the multijet-mass and leading-jet-angular distributions are approximately independent of jet multiplicity and are well described by the NJETS matrix element calculation and the HERWIG parton shower Monte Carlo predictions. The observed jet transverse momentum distributions for three- and four-jet events discriminate between the matrix element and parton shower predictions, the data favoring the matrix element calculation.
Exclusive 2-jet mass distribution.
Exclusive 3-jet mass distribution.
Exclusive 4-jet mass distribution.
We have measured the differential cross section for the inclusive production of psi(2S) mesons decaying to mu^{+} mu^{-1} that were produced in prompt or B-decay processes from ppbar collisions at 1.96 TeV. These measurements have been made using a data set from an integrated luminosity of 1.1 fb^{-1} collected by the CDF II detector at Fermilab. For events with transverse momentum p_{T} (psi(2S)) > 2 GeV/c and rapidity |y(psi(2S))| < 0.6 we measure the integrated inclusive cross section sigma(ppbar -> psi(2S)X) Br(psi(2S) -> mu^{+} mu^{-}) to be 3.29 +- 0.04(stat.) +- 0.32(syst.) nb.
The differential cross section times the dimuon branching fraction as a function of pT.
The integrated inclusive differential cross section for PSI(3685).
This paper presents the first direct measurement of the $B$ meson differential cross section, $d\sigma/dp_T$, in $p\overline{p}$ collisions at $\sqrt{s}=1.8$ TeV using a sample of $19.3 \pm 0.7$ pb$~{-1}$ accumulated by the Collider Detector at Fermilab (CDF). The cross section is measured in the central rapidity region $|y| < 1$ for $p_T(B) > 6.0$ GeV/$c$ by fully reconstructing the $B$ meson decays $B~{+}\rightarrow J/\psi K~{+}$ and $B~{0}\rightarrow J/\psi K~{*0}(892)$, where $J/\psi \rightarrow \mu~+\mu~-$ and $K~{*0} \rightarrow K~+ \pi~-$. A comparison is made to the theoretical QCD prediction calculated at next-to-leading order.
Charged B meson cross section.
Average B meson cross section (including charged and neutral).
Total integrated B meson cross section above 6 GeV.
We report on measurements of the ϒ(1S), ϒ(2S), and ϒ(3S) differential, (d2σdPtdy)y=0, and integrated cross sections in pp¯ collisions at s=1.8 TeV using a sample of 16.6 ± 0.6 pb−1 collected by the Collider Detector at Fermilab. The three resonances were reconstructed through the decay ϒ→μ+μ−. Comparison is made to a leading order QCD prediction.
SIG*Br(UPSI --> MU+ MU-).
SIG*Br(UPSI --> MU+ MU-).
SIG*Br(UPSI --> MU+ MU-).
We report measurements of the inclusive transverse momentum pT distribution of centrally produced kshort, kstar(892), and phi(1020) mesons up to pT = 10 GeV/c in minimum-bias events, and kshort and lambda particles up to pT = 20 GeV/c in jets with transverse energy between 25 GeV and 160 GeV in pbar p collisions. The data were taken with the CDF II detector at the Fermilab Tevatron at sqrt(s) = 1.96 TeV. We find that as pT increases, the pT slopes of the three mesons (kshort, kstar, and phi) are similar, and the ratio of lambda to kshort as a function of pT in minimum-bias events becomes similar to the fairly constant ratio in jets at pT ~ 5 GeV/c. This suggests that the particles with pT >~ 5 GeV/c in minimum-bias events are from soft jets, and that the pT slope of particles in jets is insensitive to light quark flavor (u, d, or s) and to the number of valence quarks. We also find that for pT <~ 4 GeV relatively more lambda baryons are produced in minimum-bias events than in jets.
The inclusive invariant differential cross section for K0S production.
The inclusive invariant differential cross section for PHI production.
The inclusive invariant differential cross section for K*(892)+- production.
We present a measurement of the isolated direct photon cross section in p-pbar collisions at sqrt(s) = 1.8 TeV and |eta| < 0.9 using data collected between 1994 and 1995 by the Collider Detector at Fermilab (CDF). The measurement is based on events where the photon converts into an electron-positron pair in the material of the inner detector, resulting in a two-track event signature. To remove pi0 -> gamma gamma and eta -> gamma gamma events we use a new background subtraction technique which takes advantage of the tracking information available in a photon conversion event. We find that the shape of the cross section as a function of pT is poorly described by next-to-leading-order QCD predictions, but agrees with previous CDF measurements.
Axis error includes +- 28/18 contribution (Correlated systematic error included in quadrature in the systematic errors.).
The growth and development of “charged particle jets” produced in proton-antiproton collisions at 1.8 TeV are studied over a transverse momentum range from 0.5 GeV/c to 50 GeV/c. A variety of leading (highest transverse momentum) charged jet observables are compared with the QCD Monte Carlo models HERWIG, ISAJET, and PYTHIA. The models describe fairly well the multiplicity distribution of charged particles within the leading charged jet, the size of the leading charged jet, the radial distribution of charged particles and transverse momentum around the leading charged jet direction, and the momentum distribution of charged particles within the leading charged jet. The direction of the leading “charged particle jet” in each event is used to define three regions of η−φ space. The “toward” region contains the leading “charged particle jet,” while the “away” region, on the average, contains the away-side jet. The “transverse” region is perpendicular to the plane of the hard 2-to-2 scattering and is very sensitive to the “underlying event” component of the QCD Monte Carlo models. HERWIG, ISAJET, and PYTHIA with their default parameters do not describe correctly all the properties of the “transverse” region.
Average number of charged particles as a function of the relative azimuthal angle between the individual charged particle and the overall leading jet angle.
Average scalar PT sum of charged particles as a function of the relative azimuthal angle between the individual charged particle for 3 different lower limits of the leading jet PT. and the overall jet angle.
The average number of toward(DPHI < 60 DEG), transverse (DPHI 60 TO 120 DEG) and away (DPHI > 120 DEG) charged particles as a function of the PT of the leading charged jet. The data in this table are from the Min-Bias events.
The transverse momentum cross section of $e^+e^-$ pairs in the $Z$-boson mass region of 66-116 GeV/$c^2$ is precisely measured using Run II data corresponding to 2.1 fb$^{-1}$ of integrated luminosity recorded by the Collider Detector at Fermilab. The cross section is compared with quantum chromodynamic calculations. One is a fixed-order perturbative calculation at ${\cal O}(\alpha_s^2)$, and the other combines perturbative predictions at high transverse momentum with the gluon resummation formalism at low transverse momentum. Comparisons of the measurement with calculations show reasonable agreement. The measurement is of sufficient precision to allow refinements in the understanding of the transverse momentum distribution.
Total integrated cross section.
The differential PT cross section as a function of PT.
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