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Hard Diffraction at D-Zero

Description: Preliminary results from the DO experiment on dijet production with forward rapidity gaps in {anti p}p collisions are presented at center-of-mass {radical}s = 1800 GeV and 630GeV. The number oi events with rapidity gaps at both center-of-mass energies is significantly greater than tne expectatmn from multiplicity fluctuations and is consistent with a hard single diffractive process. We also observe an excess of events which contain jets and two rapidity gaps, a topology which is consistent with hard double pomeron exchange.
Date: January 21, 1999
Creator: Rubinov, Paul
Partner: UNT Libraries Government Documents Department

Supersymmetry at the Tevatron?

Description: These lectures contain an introduction to the search for supersymmetry at hadron colliders. The Tevatron is one of high-energy physics most sophisticated tools. The high center-of-mass energy of its proton-antiproton collisions makes it an ideal place to search for physics beyond the Standard Model, such as supersymmetry. Two experiments, CDF and D0, completed a long data taking period in summer of 1995, yielding over 100 pb{sup -1} of proton-antiproton interactions. The data recorded by the experiments are still being analyzed. The lectures outline the strategies in the search for supersymmetry at the Tevatron and examine the major analyses in detail. Results obtained by the two experiments are included where available.
Date: February 1, 1998
Creator: Lammel, S.
Partner: UNT Libraries Government Documents Department

Jet fragmentation properties at the Tevatron

Description: Preliminary CDF results on inclusive momentum distributions of charged particles in high transverse momentum jets produced in {anti p}p collisions at {radical}s=1.8 TeV at the Tevatron are presented and compared with QCD predictions based on the Modified Leading Log Approximation.
Date: May 16, 1997
Creator: Goulianos, K.
Partner: UNT Libraries Government Documents Department

Multijet production and double parton scattering at Tevatron

Description: We report the differential cross-section for events with large total transverse energies, based on 112 pb{sup -1} p{anti p} collisions at {radical}s = 1.8 TeV. The ratio of number of 3-jet to 2-jet events as a function of total transverse energy is also presented. Obtained results are compared with the QCD expectations. The properties of high mass six-jet events have been studied. Observed distributions are compared with the predictions of HER- WIG parton shower QCD, NJETS matrix element QCD, and a phase-space model in which events are uniformly distributed in the kinematic allowed region of phase space. A strong signal for Double Parton Scattering (DP) is observed in the process {anti p}p {yields} {gamma} + 3 jets + X, using data from the CDF experiment. The fundamental DP parameter {sigma}{sub eff} obtained, {sigma}{sub eff} = 14.5 + 1.7{sup 1.7}{sub -2.3} mb, represents a significant improvement over previous measurements.
Date: June 1, 1997
Creator: Chang, P. & Collaborations, CDF and DO
Partner: UNT Libraries Government Documents Department

BFKL Tests at the Tevatron

Description: The azimuthal decorrelation of jets as a function of their rapidity separation and the dependence of the fraction of jet events with central rapidity gaps on the center of mass energy are studied in p{anti p} collisions at the Tevatron. The preliminary results on jet decorrelation are in disagreement with calculations based on the Leading Logarithmic Approximation for BFKL resummation. The preliminary results on the {radical}s--dependence of the central rapidity gap events are in disagreement with the two-gluon model for color-singlet exchange.
Date: June 1, 1997
Creator: Goussiou, A. & Collaboration, DO
Partner: UNT Libraries Government Documents Department

Search for new particles in multijet final states at the Tevatron

Description: We present the latest results of the searches for new particles in hadronic final states performed in p{anti p} collisions at {radical}s=1.8 TeV. The large data samples collected with the CDF and D0 detectors at the Tevatron collider between 1992 and 1995 allow searches for low cross section phenomena in dijet and multijet events, despite the hindrance of the high background from normal QCD processes. However no signal for new physics is found, and the data show good agreement with QCD. Limits on the mass and on the cross section of the searched states can thus be set.
Date: August 1, 1997
Creator: Dorigo, T.
Partner: UNT Libraries Government Documents Department

The dijet mass cross section at the Tevatron

Description: We present recent results on dijet production in p{anti p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron. Data from both CDF and D0 experiments are shown. Dijet measurements complement prior inclusive jet measurements, which have shown a possible excess above expectations at high transverse energy. The same trend is seen in the dijet mass spectra.
Date: May 11, 1999
Creator: Hauser, J.
Partner: UNT Libraries Government Documents Department

Probing color-singlet exchange at D0

Description: We present latest preliminary results on hard color-singlet exchange in proton-antiproton collisions. The fraction of dijet events produced via color-singlet exchange is measured as a function of jet transverse energy, dijet pseudorapidity separation, and proton-antiproton center-of-mass energy. These results are qualitatively consistent with a color-singlet fraction that increases with increasing quark-initiated processes.
Date: July 1, 1997
Creator: Abbott, B.; Abolins, M.; Acharya, B.S. & Collaboration, D0
Partner: UNT Libraries Government Documents Department

Photon and di-photon results from CDF and D0

Description: Measurements by the Fermilab D0 and CDF collaborations of prompt photon events in p{anti p} collisions at {radical}s = 1.8 TeV are reported. The measured isolated photon cross sections are compared to current parton distribution functions and NLO QCD predictions. The cross section ratio of forward to central {eta} bins and {eta} distributions are presented and compared with theoretical predictions. {gamma}+2jet events yield insight into final state radiation. A new measurement of {gamma}+{mu} events is presented which probes the charm content of the proton. Finally, di-photon results are presented as a probe of initial state radiation; these results are compared to NLO QCD, Pythia parton showers, and resummation models.
Date: May 11, 1999
Creator: Hanlet, Pierrick
Partner: UNT Libraries Government Documents Department

Tevatron physics

Description: These lectures form a personal, and not necessarily comprehensive, survey of physics at the Fermilab Tevatron proton-antiproton collider. They cover detectors, analysis issues, and physics prospects for the current Tevatron run.
Date: January 3, 2003
Creator: Womersley, John
Partner: UNT Libraries Government Documents Department

Higgs searches at the Tevatron in Run I

Description: This paper summarizes recent Higgs searches in p{anti p} collisions at {radical}s = 1.8 TeV from the Tevatron using Run I data. Emphasis is given to a new result from the CDF collaboration in searching for neutral minimal SUSY Higgs bosons through the four jet reaction p{anti p} {yields} b{anti b}{phi} {yields} b{anti b}b{anti b}. Both the CDF and D0 experiments have also searched for standard model as well as other non-standard Higgs signatures in the mass region below ~ 140 GeV/c² with no evidence of new physics.
Date: October 7, 1999
Creator: Valls, Juan A.
Partner: UNT Libraries Government Documents Department

The inclusive jet cross section at {radical}s = 630 GeV at D0

Description: The authors present a preliminary measurement of the cross section for central inclusive jet production at {radical}s = 630 GeV using {approximately} 400 nb{sup {minus}1} of data collected during the December 1995 Fermilab collider run at D0. These results are compared to NLO QCD predictions.
Date: September 1, 1996
Creator: Krane, J.
Partner: UNT Libraries Government Documents Department

Inclusive jet cross section at D0

Description: Preliminary measurement of the central ({vert_bar}{eta}{vert_bar} {<=} 0.5) inclusive jet cross sections for jet cone sizes of 1.0, 0.7, and 0.5 at D{null} based on the 1992-1993 (13.7 {ital pb}{sup -1}) and 1994-1995 (90 {ital pb}{sup -1}) data samples are presented. Comparisons to Next-to-Leading Order (NLO) Quantum Chromodynamics (QCD) calculations are made.
Date: September 1, 1996
Creator: Bhattacharjee, M.
Partner: UNT Libraries Government Documents Department

Measurement of M{sub ital W} using the transverse mass ratio of W and Z

Description: We report on the measurement of W boson mass from a determination of the ratio of the transverse masses of {ital W} and {ital Z} using the DO detector at the Fermilab Tevatron {ital p{anti p}} Collider operating at {radical}{ital s} = 1.8 TeV. The analysis is a preliminary result based on a partial data sample of 13 pb{sup -1} using W {r_arrow} {ital e{sup -}{mu}{sup +}} and Z {r_arrow} {ital e{sup -}e{sup +}} decays. The mass ratio can also be extracted by comparing the shapes of the electron E{sub T} and & distribution from W and Z decays.
Date: December 31, 1996
Creator: Rajagopalan, S.; Rijssenbeek, M. & Collaboration, D0
Partner: UNT Libraries Government Documents Department

High {Sigma}E{sub {Tau}} multijets at CDF

Description: The CDF collaboration has studied properties of 3-, 4- and 5-jet events with very high total transverse energy. An appropriate set of kinematic variables is described and two calculations based on QCD and with a phase space model. The QCD calculations are in reasonably good agreement with the data.
Date: October 1, 1996
Creator: Devlin, T.
Partner: UNT Libraries Government Documents Department

Search for squarks and gluinos using dileptons

Description: Gluinos and squarks can be produced in {ital p{anti p}} collisions at {radical}s = 1.8 TeV and decay via charginos and neutralinos to final states containing two (or more) leptons. There is no charge correlation between the leptons of charginos from gluino decays as gluinos are Majorana particles. The strategy of this analysis is to search for an excess of events containing two like-sign isolated leptons, missing energy, and jets. The analysis is based on 81 pb{sup -1} of 1994-5 data recorded at CDF.
Date: October 1, 1996
Creator: Done, J. P.
Partner: UNT Libraries Government Documents Department

Searches for supersymmetric particles in p pbar collisions with the D0 detector

Description: We report on searches for supersymmetric particles with the D0 detector at the Fermilab p{ovr p} collider at {radical}s = 1800 GeV. The four searches are: (1) for squarks and gluinos in the jets + missing transverse energy channel, (2) for a light top squark in the jets + missing transverse energy channel, (3) for squarks and gluinos in the dielectron channel, and (4) for charginos and neutralinos in the trilepton channel. The first two searches use data from the 1992- 93 collider run, and the latter two use data from the 1994-95 collider run. 6 refs., 4 figs., 1 tab.
Date: August 1, 1996
Creator: Merritt, W.
Partner: UNT Libraries Government Documents Department

Summary of recent color coherence results

Description: Recent experimental results on color coherence phenomena from e{sup +}e{sup -}, ep, and p{anti p} collisions are presented. The data are compared to analytic perturbative QCD calculations based on the modified leading logarithm approximation and the local parton hadron duality hypothesis.
Date: August 1, 1998
Creator: Varelas, N., University of Chicago
Partner: UNT Libraries Government Documents Department

Color coherence in p{bar p} collisions at {radical}s = 1.8 TeV

Description: We report on two preliminary studies of color coherence effects in pp collisions based on data collected by the D{O} detector during the 1992-1993 and 1994-1995 runs of the Fermilab Tevatron collider at a center of mass energy {radical}s = 1.8 TeV. Demonstration of initial-to-final state color interference effects is done in a higher energy region by measuring spatial correlations between the softer third jet and the second leading-ET jet in multi-jet events and in a lower energy regime by examining particle distribution patterns in W+Jet events. The data are compared to Monte Carlo simulations with different color coherence implementations and to the predictions of a NLO parton-level calculation.
Date: September 1, 1996
Creator: Cullen-Vidal, D.E.
Partner: UNT Libraries Government Documents Department

A search for disoriented chiral condensate at Fermilab

Description: A small test/experiment at the Fermilab Collider which measures charged particle and photon multiplicities in the forward direction, {eta} {approx} 4.1, has been carried out, with the primary goal being the search for disoriented chiral condensate (DCC). The author describes the experiment and analysis methods, together with preliminary results.
Date: October 1, 1996
Creator: Bjorken, J.D.
Partner: UNT Libraries Government Documents Department

Measurements of {Delta}{sigma}{sub L}(pp) and {Delta}{sigma}{sub L}({bar p}p) at 200 GeV/c

Description: A measurement was made at Fermilab of the difference in the total cross sections between states with beam and target polarizations aligned antiparallel and parallel, {Delta}{sigma}{sub L} = {Delta}{sigma}({r_reversible}) - {Delta}{sigma}({R_arrow}), using 200-GeV/c, polarized proton and antiproton beams and a polarized proton target. This measurement explores the spin dependence of particle interactions and the constituent dynamics. A difference in the spin-dependent total cross sections has been observed in previous experiments at lower energies, and this experiment was the first to explore possible spin effects in {Delta}{sigma}{sub L} at much higher energies. The polarized proton beam is produced from parity-nonconserving decays of the {Lambda}{sup 0} hyperon, where protons emitted from these decays have their spins aligned along the direction of their momenta. The {Lambda} hyperons are produced, along with other particles, when unpolarized, 800-GeV/c protons strike a beryllium target. A virtual source of protons is produced at the target from these decays and the proton polarization is correlated to the transverse distance from the target. A beam of polarized antiprotons can be produced in an analogous manner using {bar {Lambda}{sup 0}} decays. The beam transport system goal was to produce no net spin precession and to preserve the correlation between the beam particle polarization and the transverse position at the virtual source. The beam transport used four sets of quadrupole magnets to focus the beam at intermediate and final focal points. An electronic, particle-tagging system was located at the intermediate focus, while the polarized target was near the final focus.
Date: February 1, 1995
Creator: Grosnick, D.P.
Partner: UNT Libraries Government Documents Department

Measurement of W + 1 jet/W + 0 jets cross sections

Description: A preliminary measurement of the ratio W + 1 Jet/W + 0 Jets in {ital p}{ital {anti p}} collisions at {radical}s = 1800 GeV is presented. A comparison to next-to-leading order QCD finds the theory to be well below the experimental ratio even after accounting for the systematic uncertainties of the measurement. In addition, a study of both the measured and theoretical ratios as a function of minimum jet transverse energy (E{sub T}) shows that the theoretical predictions are systematically lower than the data.
Date: August 1996
Creator: Guglielmo, G.
Partner: UNT Libraries Government Documents Department

D0 top analyses: Recent results on the properties of the sixth quark

Description: The D0 collaboration updates measurements of the Standard Model top quark in pp collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron, with a new data sample of approximately twice the integrated luminosity used for the discovery measurements ({approximately}100 pb{sup -1}). We observe 37 t{bar t} candidate events from seven decay modes with an expected background of 13.4 {+-} 3.0 events. We present a preliminary new top mass measurement of 170 {+-} 15 (stat.) {+-}10 (syst.) GeV/c{sup 2} using the single-lepton + jets decay modes. For the central value of our measured mass we calculate the production cross section to be 5.2 {+-} 1.8 pb. D{O} is also analyzing additional decay modes and we report preliminary results from two new channels.
Date: June 1, 1996
Creator: Hall, R. E.
Partner: UNT Libraries Government Documents Department