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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

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

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

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

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

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

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

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

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

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

The perturbative resummed series for top production

Description: Our calculation of the total cross section for inclusive production of t{bar t} pairs in hadron collisions is summarized. Principal ingredient of this calculation is resummation of the universal leading-logarithm effect of gluon radiation to all orders in the quantum chromodynamics coupling strength, restricted to the region of phase space that is manifestly perturbative. We present predictions of the physical cross section as a function of top quark mass in proton-antiproton reactions at center-of-mass energies of 1.8 and 2.0 TeV. 7 refs., 3 figs., 2 tabs.
Date: May 2, 1996
Creator: Berger, E.L. & Contopanagos, H.
Partner: UNT Libraries Government Documents Department

CP nonconservation in p{anti p} {r_arrow} t{anti b}{Chi} at the Tevatron

Description: The reaction p{anti p} {r_arrow} t{anti b}{Chi} is found to be rather rich in exhibiting several different types of CP asymmetries. The spin of the top quark plays an important role. Asymmetries are related to form factors arising from radiative corrections of the t{anti b}W production vertex due to non-standard physics. As illustrations, effects are studied in two Higgs Doublet Models and in Supersymmetric Models; asymmetries up to a few percent may be possible.
Date: June 1996
Creator: Atwood, David; Bar-Shalom, Shaouly; Eilam, Gad & Soni, Amarjit
Partner: UNT Libraries Government Documents Department

Some notes on long-range beam-beam effects for the 2 TeV collider

Description: The 2 TeV {bar p}-p collider discussed at this workshop would necessarily have hundreds of long-range interactions between the counter-rotating bunches and some of the low-order effects of these interactions are estimated below. We discuss in this paper how the helical orbit around the accelerator will help alleviate some of these effects, though the tune spread due to the long-range interactions will be present.
Date: December 31, 1994
Creator: Syphers, M.J.
Partner: UNT Libraries Government Documents Department

Measurement of the B{sup +} and B{sup 0} lifetimes at CDF

Description: Two measurements of the lifetime of neutral and charged B mesons in p{bar p} collisions at {radical}s = 1.8 TeV by the CDF experiment are presented. The first relies on the study of exclusive decays of the type B {yields} {psi} K, the second on semileptonic decays of a B meson into a D{degrees} or a D. The combined results are {tau}(B{sup +}) = 1.62 {+-} 0.09 ps, {tau}(B{sub 0}) = 1.60 {+-} 0.09 ps and {tau}(B{sup +})/{tau}(B{sup 0}) = 1.00 {+-} 0.07.
Date: October 1, 1995
Creator: Bortoletto, D.
Partner: UNT Libraries Government Documents Department

Limits on new particle production in p pbar collisions from D0

Description: Despite its overwhelming experimental success, there is compelling reason to believe that the Standard Model is not the final word. D0 has been actively pursuing many possible extensions to the Standard Model, and we report on several of our searches in this paper. All of the searches on which we report are based on the data sample collected during Tevatron Run.
Date: December 1, 1995
Creator: Wightman, J.A.
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

Electroweak and flavor dynamics at hadron colliders - I

Description: This is the first of two reports cataloging the principal signatures of electroweak and flavor dynamics at {anti p}p and pp colliders. Here, we discuss some of the signatures of dynamical electroweak and flavor symmetry breaking. The framework for dynamical symmetry breaking we assume is technicolor, with a walking coupling {alpha}{sub TC}, and extended technicolor. The reactions discussed occur mainly at subprocess energies {radical}{cflx s}{approx_lt} 1 TeV. They include production of color-singlet and octet technirhos and their decay into pairs of technipions, longitudinal weak bosons, or jets. Technipions, in turn, decay predominantly into heavy fermions. This report will appear in the Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics (Snowmass 96).
Date: February 1, 1998
Creator: Elchtent, E. & Lane, K.
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

The D-Zero luminosity monitor constant for {radical} {ital s} = 630 GeV

Description: D0 has calculated the luminosity monitor constant for {radical}s= 630 GeV. The inelastic p{anti p} cross section was interpolated between measurements performed at {radical}s = 546 and 1800 GeV. The geometric acceptance, hardware efficiency, and luminosity-dependent corrections are similar to those previously published for the full Tevatron energy. We find a luminosity-weighted value of {sigma}{sub L0} = 34.04 {+-} 1.05 mb, yielding a precision of {+-} 3.08%.
Date: June 1, 1997
Creator: Krane, J.; Barnly, J. & Owen, D.
Partner: UNT Libraries Government Documents Department

QCD aspects of W/Z production at the Tevatron

Description: Hadron colliders are providing valuable opportunities for studying the influence of the strong force on electroweak interactions in both the perturbative and non-perturbative regions. At the Fermilab Tevatron, analysis by CDF and D0 of p{anti p} {yields} W/Z + X events at {radical}s = 1.8 TeV have been used to test a variety of leading order and next-to-leading order QCD predictions. Among the many promising benefits are improvements of parton distribution functions at high Q{sup 2} , demonstration of soft gluon radiation patterns which survive hadronization, and tests of perturbative QCD and resummation calculations.
Date: July 1, 1997
Creator: Guglielmo, G. & Collaborations, CDF and D0
Partner: UNT Libraries Government Documents Department

Determination of the b-quark production cross section in p{anti p} collisions at 630 GeV

Description: We present a preliminary measurement of the b-quark production cross section in p{anti p} collisions at {radical}s = 630 GeV. The analysis is based on 340 nb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron Collider. We determine the ratio of the b-quark production cross sections at 630 GeV to 1800 GeV and compare our results with the CDF and UA1 measurements, and with the next-to- leading order QCD predictions.
Date: October 1, 1997
Creator: Abbott, B.
Partner: UNT Libraries Government Documents Department

Tevatron status and future plans

Description: The performance of the Fermilab accelerator complex, which has led to the recent discovery of the top quark, is described. The status of the Tevatron at the end of the 4 year collider run and at the beginning of the fixed target run and of the Main Injector project is presented. It is expected that the Main Injector and other improvements in the complex will increase the luminosity up to 2 x 10{sup 12} cm{sup -2} s{sup -1} and will provide a high intensity 120 GeV proton beam to allow for a search for neutrino oscillations. Activities under consideration beyond the next collider run are discussed which can lead to a peak luminosity of 10{sup 33} cm{sup -2} s{sup -1}.
Date: November 1, 1996
Creator: Finley, D.A.; Marriner, J. & Mokhov, N.V.
Partner: UNT Libraries Government Documents Department