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Kaon condensation in dense stellar matter

Description: This article combines two talks given by the authors and is based on Works done in collaboration with G.E. Brown and D.P. Min on kaon condensation in dense baryonic medium treated in chiral perturbation theory using heavy-baryon formalism. It contains, in addition to what was recently published, astrophysical backgrounds for kaon condensation discussed by Brown and Bethe, a discussion on a renormalization-group analysis to meson condensation worked out together with H.K. Lee and S.J. Sin, and the recent results of K.M. Westerberg in the bound-state approach to the Skyrme model. Negatively charged kaons are predicted to condense at a critical density 2 {approx_lt} {rho}/{rho}o {approx_lt} 4, in the range to allow the intriguing new phenomena predicted by Brown and Bethe to take place in compact star matter.
Date: March 1, 1995
Creator: Lee, Chang-Hwan & Rho, M.
Partner: UNT Libraries Government Documents Department

RG analysis of magnetic catalysis in dynamical symmetry breaking

Description: We perform the renormalization group analysis on the dynamical symmetry breaking under strong external magnetic field, studied recently by Gusynin, Miransky and Shovkovy. We find that any attractive four-Fermi interaction becomes strong in the low energy, thus leading to dynamical symmetry breaking. When the four-Fermi interaction is absent, the {beta}-function for the electromagnetic coupling vanishes in the leading order in 1/N. By solving the Schwinger-Dyson equation for the fermion propagator, we show that in 1/N expansion, for any electromagnetic coupling, dynamical symmetry breaking occurs due to the presence of Landau energy gap by the external magnetic field. 5 refs.
Date: May 1, 1996
Creator: Hong, Deog Ki & Kim, Youngman
Partner: UNT Libraries Government Documents Department

Finite-temperature corrections in the dilated chiral quark model

Description: We calculate the finite-temperature corrections in the dilated chiral quark model using the effective potential formalism. Assuming that the dilaton limit is applicable at some short length scale, we interpret the results to represent the behavior of hadrons in dense and hot matter. We obtain the scaling law, f{sub {pi}}(T)/f{sub {pi}} = m{sub Q}(T)/m{sub Q} {approx_equal} m{sub {sigma}}(T)/m{sub {sigma}}while we argue, using PCAC, that pion mass does not scale within the temperature range involved in our Lagrangian. It is found that the hadron masses and the pion decay constant drop faster with temperature in the dilated chiral quark model than in the conventional linear sigma model that does not take into account the QCD scale anomaly. We attribute the difference in scaling in heat bath to the effect of baryonic medium on thermal properties of the hadrons. Our finding would imply that the AGS experiments (dense and hot matter) and the RHIC experiments (hot and dilute matter) will ``see`` different hadron properties in the hadronization exit phase.
Date: March 1, 1995
Creator: Kim, Y.; Lee, Hyun Kyu & Rho, M.
Partner: UNT Libraries Government Documents Department

Composite particle production in relativistic Au+Au collisions at AGS: First results from the E866 forward spectrometer @ 2, 4, and 10.8 A{center_dot}GeV

Description: Particle spectra were measured for Au + Au collisions at 2, 4, and 10. 8 A{center_dot}GeV using the E866 spectrometers. Recent results on proton emission and composite particle production form the E866 forward spectrometer data taken in 1994 together with the first results from the 1995/6 AGS running period are presented. Preliminary results indicate a decrease in the coalescence scaling coefficient with increasing projectile energy and centrality.
Date: December 31, 1996
Creator: Ashktorab, K.
Partner: UNT Libraries Government Documents Department

Two particle correlations at mid-rapidity in Si+A and Au+Au from E859/E866

Description: Two particle correlation measurements for {ital Si-A} and {ital Au- Au} collisions from Brookhaven E859 and E866 are discussed. These measurements allow us, with some interpretation, to deduce the size of the participant region in a heavy ion collision. We show that various source parameterizations yield consistent results and we explore the dependence of the apparent source size on the pion yield.
Date: February 1, 1997
Creator: Baker, M.D. & Collaboration, E802
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

The dijet mass spectrum with the D0 detector

Description: The authors present preliminary results from an analysis of dijet data collected during the 1994--1995 Tevatron Collider run with an integrated luminosity of 91 pb{sup {minus}1}. Measurements of dijet mass spectrum distributions in {anti p}p collisions at {radical}s = 1.8 TeV are compared with next-to-leading order QCD theory.
Date: September 1, 1996
Creator: Choi, S.
Partner: UNT Libraries Government Documents Department

A study of multi-jet production ratios in p{anti p} collisions at D0

Description: The authors study inclusive jet multiplicity ratios in multi-jet events from p{anti p} collisions at {radical}s = 1.8 TeV recorded using the D0 detector at the Fermilab Tevatron collider. Preliminary average multi-jet production ratios are presented as a function of the scalar jet transverse energy and compared to NLO calculations.
Date: September 1, 1996
Creator: Gallas, E.
Partner: UNT Libraries Government Documents Department

The b{bar b} production cross section and correlations in p{bar p} collisions at {radical}s = 1.8 TeV

Description: The authors present measurements of the b{bar b} production cross section and angular correlations between the b and {bar b}-quarks in p{bar p} collisions using the D0 detector at the Fermilab Tevatron operating at {radical}s = 1.8 TeV. The b-quark production cross section for {vert_bar}y{sup b}{vert_bar} < 1.0 and {rho}{sub {tau}}{sup b} > 8 GeV/c is extracted and found to be consistent with next-to-leading order QCD predictions. In addition, the angular correlations between the b and {bar b}-quarks are found to agree in shape with next-to-leading order QCD predictions.
Date: August 1, 1996
Creator: Gomez, B.; Hoeneisen, B. & Negret, J.P.
Partner: UNT Libraries Government Documents Department

Inclusive jet cross section in p{bar p} collisions with the D0 detector

Description: The authors report on two preliminary measurements of the central inclusive jet cross section at {radical}s = 1.8 TeV. The two data sets with integrated luminosities of 91 pb{sup {minus}1} and 14 pb{sup {minus}1} were collected at the Fermilab Tevatron p{bar p} Collider with the D0 detector. The cross section, reported as a function of transverse jet energy 35 GeV {le} E{sub {tau}} {le} 470 GeV and in the pseudorapidity interval {vert_bar}{eta}{vert_bar} {le} 0.5, is in excellent agreement with next-to-leading order QCD.
Date: July 1, 1996
Creator: Gomez, B.; Hoeneisen, B. & Negret, J.P.
Partner: UNT Libraries Government Documents Department

Tests of QCD in W and Z production at Tevatron

Description: We present measurements of the production cross sections times leptonic branching fractions and the transverse momentum distributions of W and Z bosons in p{bar p} collisions at {radical}s = 1.8 TeV using data collected with the DO detector at the Fermilab Tevatron p{bar p} collider. A preliminary measurement of the W charge asymmetry is also presented.
Date: August 1, 1995
Creator: Abachi, S. & Collaboration, The D0
Partner: UNT Libraries Government Documents Department

Search for first and second generation leptoquarks at D0

Description: A search for first and second generation pair produced scalar leptoquarks has been done with the DO detector at Fermilab`s p{bar p} machine with {radical}s = 1.8 TeV. Leptoquarks are assumed to be strictly generational; for example, a first generation leptoquark couples only to the electron, its neutrino, and the u and d quarks. 95% C.L. mass limits of 133 GeV/c{sup 2} and 120 GeV/c{sup 2} for respective 100% and 50% decay branching ratios to electron plus quark for first generation scalar leptoquarks have been published. The preliminary results of a search for second generation scalar leptoquarks in the absence of a signal are mass limits of 111 GeV/c{sup 2} and 89 GeV/c{sup 2} for 100% and 50% decay branching ratios to muon plus quark. A feature of these mass limits is that they are independent of the unknown coupling of the leptoquark to leptons and quarks. The detection for e{sup +}e{sup {minus}} and e-p machines depends on the strength of this coupling.
Date: July 1, 1995
Creator: Abachi, S.; Abbott, B. & Abolins, M.
Partner: UNT Libraries Government Documents Department

J/{psi} production in p{anti p} collisions at {radical}s = 1.8 TeV

Description: The authors have studied J/{psi} production in p{anti p} collisions at {radical}s = 1.8 TeV with the D0 detector at Fermilab, using a {mu}{sup +}{mu}{sup {minus}} data sample corresponding to an integrated luminosity of 13 pb{sup {minus}1}. They have measured the inclusive J/{psi} production cross section as a function of J/{psi} transverse momentum p{sub T}. For the kinematic range p{sub T} > 8 GeV/c and {vert_bar}{eta}{vert_bar} < 0.6 they obtain Br(J/{psi} {yields} {mu}{sup +}{mu}{sup {minus}}) {center_dot} {sigma}(p{anti p} {yields} J/{psi} + X) = 1.93 {+-} 0.16(stat) {+-} 0.43(syst) nb. Using the muon impact parameter they have estimated the fraction of J/{psi} mesons coming from B meson decays to be f{sub b} = 0.35 {+-} 0.09 (stat) {+-} 0.10 (syst) and inferred the inclusive b production cross section. From the information on the event topology a fraction of non-isolated J/{psi} events has been measured to be f{sub non-isol} = 0.64 {+-} 0.09(stat) {+-} 0.06(syst). They have also obtained the fraction of events resulting from radiative decays of {chi}{sub c} states as f{sub {chi}} = 0.30 {+-} 0.07(stat) {+-} 0.07(syst). They discuss the implications of the measurements for charmonium production processes.
Date: July 1, 1995
Creator: Abachi, S.
Partner: UNT Libraries Government Documents Department

D{O} top quark mass analysis

Description: Based on (44-48 pb{sup -1}) of lepton + jets data, we review D0`s initial analysis of the top quark mass. The result, M{sub top} = 199 {+-} 19/21 (stat.) {+-} 22 (syst.) GeV/c{sup 2}, is insensitive to background normalization. The errors are based on ISAJET top Monte Carlo, with its more severe gluon radiation, and allow for ISAJET/HERWIG differences. Good progress is being made in reducing the systematic error. We present a new study based on two-dimensional distributions of reconstructed top quark vs. dijet mass. With 98.7% confidence we observe a peak in the top mass - dijet mass plane. The peak and its projections are similar both in shape and magnitude to expectations based on the decay sequence 1 {yields} bW, W {yields} jj.
Date: July 1, 1995
Creator: Strovink, M.
Partner: UNT Libraries Government Documents Department

Measurement of the {gamma} cross section at D0 using dimuons

Description: The D0 experiment has measured the {gamma} differential cross section in p{bar p} collisions at {radical}s = 1.8 TeV for {vert_bar}y{sup {gamma}}{vert_bar} < 0.7. We find the measured cross section to be a factor of five larger than the O({alpha}{sub s}{sup 3}) QCD prediction for p{sub T}{sup {gamma}} > 5 GeV/c.
Date: July 1995
Creator: Abachi, S.; Abbott, B. & Abolins, M.
Partner: UNT Libraries Government Documents Department

Hadronic Calibration of D0 Calorimetry

Description: The D{null} detector is used to study {ital p{anti p}} collisions at the 1.8 TeV center-of-momentum energies available at the Fermilab Tevatron. The heart of the detector is a hermetic calorimeter employing uranium absorber and liquid argon as the ionization sampling medium. Several analyses require a well-understood jet energy scale. This paper describes how this calibration is obtained.
Date: September 1, 1996
Creator: Kehoe, R.
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

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

Jet angular decorrelation and color coherence in p{bar p} collisions at {radical}s = 1.8 TeV

Description: We present three QCD studies based on data collected by the d{O} detector during the 1992-1993 and 1994-1995 runs at the Fermilab Tevatron collider at center of mass energy {radical}s = 1.8 TeV. The first study is an analysis of jet-jet azimuthal decorrelation as a function of jet rapidity separation. The second and third studies are probes of color coherence effects in hadronic collisions - one using multi-jet events and the other using W+jet events.
Date: August 1, 1996
Creator: Jaques, J.
Partner: UNT Libraries Government Documents Department

D0 measurements of beauty production in p{bar p} collisions at {radical}s = 1.8 TeV

Description: We report a number of results on beauty production from the D{null} experiment at the Fermilab Tevatron Collider operating at {radical}s = 1.8 TeV. Measurements of the {ital b}{ital {anti b}} production cross section using single muon, muon plus jet and dimuon plus jet triggers, in the data collected in 1992-93, are presented. A preliminary measurement of the {ital b}{ital {anti b}} angular correlations using the dimuon data sample is also presented. We find that the {ital b}-quark production cross section for {vert_bar}{ital Y}{sup b}{vert_bar} {lt} 1.0 and {ital p}{sub T}{sup b} {gt} 8 GeV/c is systematically higher than, although consistent within errors with, the next-to-leading order (NLO) QCD predictions. A similar comparison with QCD is observed in the {ital b}{ital {anti b}} ({mu}{mu}) angular correlations, where the shape of the distribution indicates a sizable contribution fro the NLO process.
Date: September 1, 1996
Creator: Baarmand, M. M.
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

Rapidity dependence of the inclusive J/{psi} production in p{bar p} collisions at {radical}s = 1.8 TeV

Description: We have studied the {ital J}/{psi} production in {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV with the D{null} detector at the Fermilab Tevatron, using a {mu}{sup +}{mu}{sup -} data sample collected during the 1994-95 running period. We have measured the inclusive {ital J}/{psi} production cross section as a function of the {ital J}/{psi} transverse momentum, {ital P}{sub T}{sup {ital J}/{psi}} in the central and forward rapidity regions. The new measurement of the cross section {ital d{sigma}/dp}{sub T}{sup {ital J}/{psi}} for {vert_bar}{eta}{sup {ital J}/{psi}}{vert_bar} {lt} 0.6 is in a good agreement with the CDF and earlier D{null} results. The cross section measurement {ital d{sigma}/dp}{sub T}{sup {ital J}/{psi}} for 2.5 {lt} {vert_bar}{eta}{sup {ital J}/{psi}}{vert_bar} {lt} 3.7 covers the {ital p}{sub T}{sup {ital J}/{psi}} range from 1 to 16 GeV/c. We combine the measurements in several {vert_bar}{eta}{sup {ital J}/{psi}}{vert_bar} regions to discuss {ital d{sigma}/d{eta}}{sup {ital J}/{psi}} for {ital p}{sub T}{sup {ital J}/{psi}} {gt} 8 GeV/c. The data are compared with the next-to- leading order (NLO) QCD calculations, which take into account different {ital J}/{psi} production mechanisms.
Date: August 1, 1996
Creator: D0 Collaboration
Partner: UNT Libraries Government Documents Department

D0 top quark cross section for the 1992--1995 tevatron run

Description: We present a measurement of the t{bar t} cross section in p{bar p} collisions at {radical}s = 1.8 TeV using dilepton and single lepton final states. This analysis uses about 100 pb{sup -1} of data collected with the D0 detector at Fermilab during the 1992-1995 run. Analyses in two other final states are also presented. 13 refs., 3 figs., 2 tabs.
Date: October 1, 1996
Creator: Bantly, J.
Partner: UNT Libraries Government Documents Department

Hard single diffractive jet production at D0

Description: Preliminary results from the D{null} experiment on jet production with forward rapidity gaps in {ital p{anti p}} collisions are presented. A class of dijet events with a forward rapidity gap is observed at center-of-mass energies {radical}s = 1800 GeV and 630 GeV. The number of events with rapidity gaps at both center-of-mass energies is significantly greater than the expectation from multiplicity fluctuations and is consistent with a hard single diffractive process. A small class of events with two forward gaps and central dijets is also observed at 1800 GeV. This topology is consistent with hard double pomeron exchange.
Date: August 1, 1996
Creator: Abachi, S.; Abbott, B.; Abolins, M. & Collaboration, D0
Partner: UNT Libraries Government Documents Department