Showing papers by "Kostantinos Kordas published in 2000"
TL;DR: In this article, the authors measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995.
Abstract: We have measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at sqrt[s] = 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995. The polarization of promptly produced J/psi [psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5]
134 citations
TL;DR: The transverse momentum and total cross section of e(+)e(-) pairs in the Z-boson region of 66
Abstract: The transverse momentum and total cross section of e{sup +}e{sup -} pairs in the Z -boson region of 66
122 citations
TL;DR: In this paper, a study of events with a leading antiproton of beam momentum fraction 0.905 7 GeV was conducted and the authors evaluated the diffractive structure function of the anti-photon and compared it with expectations based on results obtained in diffractive deep inelastic scattering experiments at the DESY ep collider HERA.
Abstract: We report results from a study of events with a leading antiproton of beam momentum fraction 0.905 7 GeV. Using the dijet events, we evaluate the diffractive structure function of the antiproton and compare it with expectations based on results obtained in diffractive deep inelastic scattering experiments at the DESY ep collider HERA.
111 citations
TL;DR: In this paper, the authors reported an updated measurement of the standard model CP violation parameter sin 2{beta} using the CDF Detector at Fermilab, where the entire run I data sample of 110 pb{sup -1} of proton-antiproton collisions at {radical}(s)=1.8 TeV is used to identify a signal sample of {approx}400 B{yields}J/{psi} K{sub S}{sup 0} events, where J/
Abstract: This paper reports an updated measurement of the standard model CP violation parameter sin 2{beta} using the CDF Detector at Fermilab. The entire run I data sample of 110 pb{sup -1} of proton-antiproton collisions at {radical}(s)=1.8 TeV is used to identify a signal sample of {approx}400 B{yields}J/{psi} K{sub S}{sup 0} events, where J/{psi}{yields}{mu}{sup +}{mu}{sup -} and K{sub S}{sup 0}{yields}{pi}{sup +}{pi}{sup -}. The flavor of the neutral B meson is identified at the time of production by combining information from three tagging algorithms: a same-side tag, a jet-charge tag, and a soft-lepton tag. A maximum likelihood fitting method is used to determine sin 2{beta}=0.79{sub -0.44}{sup +0.41}(stat+syst). This value of sin 2{beta} is consistent with the standard model prediction, based upon existing measurements, of a large positive CP-violating asymmetry in this decay mode. (c) 2000 The American Physical Society.
99 citations
TL;DR: The first observation of dijet events with a double Pomeron exchange topology produced in &pmacr;p collisions at sqrt[s] = 1800 GeV is reported.
Abstract: We report the first observation of dijet events with a double Pomeron exchange topology produced in (p) over barp, collisions at roots = 1800 GeV. The events are characterized by a leading antiproton, two jets in the central pseudorapidity region, and a large rapidity gap on the outgoing proton side. We present results on jet kinematics and production rates, compare them with corresponding results from single diffractive and inclusive dijet production, and test factorization.
58 citations
TL;DR: The ratio of diffractive to total b-quark production rates is found to be R(&bmacr;b) = [0.62+/-0.19(stat)+/- 0.16(syst)], significantly lower than expectations based on factorization.
Abstract: We report a measurement of the fraction of b quarks produced diffractively in p(bar sign) p collisions at {radical}(s)=1.8 TeV. Diffraction is identified by the absence of particles in a forward pseudorapidity region. From events with an electron of transverse momentum 9.5
41 citations
TL;DR: In this article, the authors used results from a search for top quark pair production by the Collider Detector at Fermilab (CDF) in the e{tau+Ee{sub T}+jets and {mu}{tau}+Eebt+Jets signatures to set an upper limit on the branching ratio of B(t{yields}H{sup +}b) in 106 pb{sup -1} of data.
Abstract: Top quark production offers the unique opportunity to search for a charged Higgs boson (H{sup {+-}}), as the contribution from t{yields}H{sup +}b{yields}{tau}{sup +}{nu}b can be large in extensions of the standard model. We use results from a search for top quark pair production by the Collider Detector at Fermilab (CDF) in the e{tau}+Ee{sub T}+jets and {mu}{tau}+Ee{sub T}+jets signatures to set an upper limit on the branching ratio of B(t{yields}H{sup +}b) in 106 pb{sup -1} of data. The upper limit is in the range 0.5 to 0.6 at 95% C.L. for H{sup +} masses in the range 60 to 160 GeV, assuming the branching ratio for H{sup +}{yields}{tau}{nu} is 100%. The {tau} lepton is detected through its 1-prong and 3-prong hadronic decays. (c) 2000 The American Physical Society.
40 citations
TL;DR: In this article, the authors search for direct production of scalar top quarks at the Collider Detector at Fermilab in 88 pb{sup -1} of pp collisions at {radical}(s)=1.8 TeV.
Abstract: We have searched for direct production of scalar top quarks at the Collider Detector at Fermilab in 88 pb{sup -1} of pp collisions at {radical}(s)=1.8 TeV . We assume the scalar top quark decays into either a bottom quark and a chargino or a bottom quark, a lepton, and a scalar neutrino. The event signature for both decay scenarios is a lepton, missing transverse energy, and at least two b -quark jets. For a chargino mass of 90 GeV/c{sup 2} and scalar neutrino masses of at least 40 GeV/c{sup 2} , we find no evidence for scalar top production and present upper limits on the production cross section in both decay scenarios. (c) 2000 The American Physical Society.
28 citations
TL;DR: The results of a search for second and third generation leptoquarks using 88 pb{sup -1} of data recorded by the Collider Detector at Fermilab were reported in this article.
Abstract: We report the results of a search for second and third generation leptoquarks using 88 pb{sup -1} of data recorded by the Collider Detector at Fermilab. Color triplet technipions, which play the role of scalar leptoquarks, are investigated due to their potential production in decays of strongly coupled color octet technirhos. Events with a signature of two heavy flavor jets and missing energy may indicate the decay of a second (third) generation leptoquark to a charm (bottom) quark and a neutrino. As the data are found to be consistent with standard model expectations, mass limits are determined.
26 citations
TL;DR: In this article, the production of B hadrons in 1.8-TeV pp(bar sign) collisions was studied and the fragmentation fractions of produced b quarks were measured.
Abstract: We have studied the production of B hadrons in 1.8-TeV pp(bar sign) collisions. We present measurements of the fragmentation fractions, f{sub u} , f{sub d} , f{sub s} , and f{sub baryon} , of produced b quarks that yield B{sup +} , B{sup 0} , B{sup 0}{sub s} , and {lambda}{sup 0}{sub b} hadrons. Reconstruction of five electron-charm final states yields f{sub s}/( f{sub u}+f{sub d})=0.213{+-}0.068 and f{sub baryon}/( f{sub u}+f{sub d})=0.118{+-}0.042 , assuming f{sub u}=f{sub d} . If all B hadrons produced in pp(bar sign) collisions cascade to one of these four hadrons, we determine f{sub u}=f{sub d}=0.375{+-}0.023 , f{sub s}=0.160{+-}0.044 , and f{sub baryon}=0.090{+-}0.029 . If we do not assume f{sub u}=f{sub d} , we find f{sub d}/f{sub u}=0.84{+-}0.16 . (c) 2000 The American Physical Society.
24 citations
TL;DR: The results of a search for pair production of a fourth-generation charge -1 / 3 quark (b(')) in 1.8 TeV pp collisions using 88 pb(-1) of data obtained with the Collider Detector at Fermilab were presented in this article.
Abstract: We present the results of a search for pair production of a fourth-generation charge -1 / 3 quark (b(')) in sqrt[s] = 1.8 TeV pp collisions using 88 pb(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b(')-->bZ(0) and that the b(') mass is greater than m(Z)+m(b). We studied the decay mode b(')b(');-->Z(0)Z(0)bb where one Z0 decays into e(+)e(-) or m(+)m(-) and the other decays hadronically, giving a signature of two leptons plus jets. An upper limit on the sigma(pp-->b(')b(');)x[B(b(')-->bZ(0))](2) is established as a function of the b(') mass. We exclude at 95% confidence level a b(') quark with mass between 100 and 199 GeV/c(2) for B(b(')-->bZ(0)) = 100%.
TL;DR: In this article, a measurement of the cross section for production of two or more jets as a function of dijet mass, based on an integrated luminosity of 86 pb{sup -1} collected with the Collider Detector at Fermilab, is presented.
Abstract: We present a measurement of the cross section for production of two or more jets as a function of dijet mass, based on an integrated luminosity of 86 pb{sup -1} collected with the Collider Detector at Fermilab. Our dijet mass spectrum is described within errors by next-to-leading order QCD predictions using CTEQ4HJ parton distributions, and is in good agreement with a similar measurement from the DOe experiment. (c) 2000 The American Physical Society.
TL;DR: In this article, the authors consider the production of light gravitinos and set a limit at 95% confidence level on the breaking scale root F greater than or equal to 217 GeV, which excludes gravitino masses smaller than 1.1 X 10(-5) eV/c(2).
Abstract: Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the standard model. We see no deviations from the expected backgrounds and set upper limits on the production of new processes. We consider in addition the production of light gravitinos and set a limit at 95% confidence level on the breaking scale root F greater than or equal to 217 GeV, which excludes gravitino masses smaller than 1.1 X 10(-5) eV/c(2).
TL;DR: In this paper, the authors search for color singlet technirho and technipion production in $p\overline{p}$ collisions at the Fermilab Collider.
Abstract: We search for color singlet technirho and technipion production in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\phantom{\rule{0ex}{0ex}}\mathrm{TeV}$ recorded with the Collider Detector at Fermilab. These exotic technimesons are present in a model of walking technicolor. The signatures studied are lepton plus two jets plus ${E}_{T}$ and multijet final states. No excess of events is seen in either final state. We set an upper limit on the technirho production cross section and exclude a region in the technipion mass versus technirho mass plane.
TL;DR: The first measurement of the rapidity distribution dsigma/dy over nearly the entire kinematic region of rapidity for e^+e^- pairs in the Z-boson region of 66 116 GeV/c^2 was reported in this article.
Abstract: We report on the first measurement of the rapidity distribution dsigma/dy over nearly the entire kinematic region of rapidity for e^+e^- pairs in the Z-boson region of 66 116 GeV/c^2. The data sample consists of 108 pb^{-1} of ppbar collisions at \sqrt{s}=1.8 TeV taken by the Collider Detector at Fermilab during 1992--1995. The total cross section in the $Z$-boson region is measured to be 252 +- 11 pb. The measured total cross section and d\sigma/dy are compared with quantum chromodynamics calculations in leading and higher orders.
TL;DR: In this paper, a direct measurement of the total decay width of the W boson Gamma(W) is presented using 350 pb(-1) of data from pp[over ] collisions at square root s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron.
Abstract: A direct measurement of the total decay width of the W boson Gamma(W) is presented using 350 pb(-1) of data from pp[over ] collisions at square root s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. The width is determined by normalizing predicted signal and background distributions to 230 185 W candidates decaying to enu and micronu in the transverse-mass region 50