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Top quark physics: Future measurements

Description: The authors discuss the study of the top quark at future experiments and machines. Top`s large mass makes it a unique probe of physics at the natural electroweak scale. They emphasize measurements of the top quark`s mass, width, and couplings, as well as searches for rare or nonstandard decays, and discuss the complementary roles played by hadron and lepton colliders.
Date: April 4, 1997
Creator: Frey, R.; Vejcik, S. & Berger, E.L.
Partner: UNT Libraries Government Documents Department

W {right arrow} {tau}{nu} and Gamma{sub W} studies at the Tevatron collider

Description: The most recent results on the studies of the W properties, namely of the process W{yields}{tau}{nu} and of the {Gamma}{sub W} measurements performed in {anti p}p collisions at {radical}s=1800 GeV, are reported. The data are from the two experiments operating at the Tevatron Collider, CDF and DO.
Date: May 3, 1999
Creator: Rimondi, F.
Partner: UNT Libraries Government Documents Department

Radiative width of the a {subscript 2} meson

Description: We present data on coherent production of the ({pi}{sup +}{pi}{sup -}{pi}{sup -}) system by 600 GeV/c pion beam in the reaction {pi}{sup -} + A {yields} A + ({pi}{sup +}{pi}{sup -}{pi}{sup -}) for the C, Cu and Pb targets. The Primakoff formalism was used for extracting the radiative width of the a{sub 2} meson. We obtain a preliminary value {Gamma}(a{sub 2}{sup -} {yields} {pi}{sup -}{gamma}) = 225 {+-} 25(stat) {+-} 45(syst) keV.
Date: May 3, 1999
Creator: al., V.P. Kubarovsky et
Partner: UNT Libraries Government Documents Department

Lifetime difference of B{sub s} mesons and its implications

Description: The authors discuss the calculation of the width difference {Delta}{Gamma}{sub B}, between the B{sub s} mass eigenstates to next-to-leading order in the heavy quark expansion. 1/m{sub b}-corrections are estimated to reduce the leading order result by typically 30%. The error of the present estimate ({Delta}{Gamma}/{Gamma}){sub B{sub s}} = 0.16{sub {minus}0.09}{sup +0.11} could be substantially improved by pinning down the value of <{anti B}{sub s}{vert_bar}({anti b}{sub i}s{sub i}){sub S{minus}P}({anti b}{sub j}s{sub j}){sub S{minus}P}{vert_bar}B{sub s}> and an accuracy of 10% in ({Delta}{Gamma}/{Gamma}){sub B{sub s}} should eventually be reached. They briefly mention strategies to measure ({Delta}{Gamma}/{Gamma}){sub B{sub s}}, and its implications for constraints on {Delta}M{sub B{sub s}}, CKM parameters and the observation of CP violation in untagged B{sub s} samples.
Date: August 1, 1996
Creator: Beneke, M.
Partner: UNT Libraries Government Documents Department

Pauli Interference in the 't Hooft model: Heavy quark expansion and quark-hadron duality

Description: Pauli Interference in decays of heavy flavor mesons, a genuinely nonleptonic nonperturbative effect, is considered in the 't Hooft model. Analytic summation of the exclusive decay widths yields the same expression as obtained in the OPE-based approach. Threshold-related violations of local duality in PI are found to be suppressed. A novel case is identified where the OPE effect is completely saturated by a single final state.
Date: March 1, 1999
Creator: Bigi, Ikaros & Uraltsev, Nikolai
Partner: UNT Libraries Government Documents Department

Report of the working group on precision measurements - measurements of the W boson mass and width.

Description: We discuss the prospects for measuring the W mass and width in Run II. The basic techniques used to measure M{sub W} are described and the statistical, theoretical and detector-related uncertainties are discussed in detail. Alternative methods of measuring the W mass at the Tevatron and the prospects for M{sub W} measurements at other colliders are also described.
Date: November 29, 2000
Creator: Brock, R.; Erler, J.; Kim, Y.-K.; Marciano, W.; Ashmanskas, W.; Baur, U. et al.
Partner: UNT Libraries Government Documents Department

The mass and width of the W boson

Description: The Tevatron and LEP2 experiments presently provide the most precise direct determinations of the mass and width of the W boson. The combined results are: M{sub w} = 80.394 {+-} 0.042 GeV and {Gamma}{sub w} = 2.095 {+-} 0.106 GeV. The results are in excellent agreement with the predictions of the Standard Model. In this article the latest results are described and the systematic errors which could limit further significant improvements in the precision of these measurements are reviewed.
Date: February 9, 2000
Creator: Lancaster, M.
Partner: UNT Libraries Government Documents Department

D-Zero results on W boson properties

Description: The D0 experiment collected {approx} 15 pb{sup -1} in run 1A (1992- 1993) and {approx} 89 pb{sup -1} in run 1B (1994-1995) of the Fermilab Tevatron Collider using p{anti p} collisions at {radical}s = 1.8 TeV. Results from analyses of events with W and Z bosons are presented for the run 1B data samples. From W {yields} e{nu}, {mu}{nu} and Z {yields} ee, {mu}{mu} decays, the W and Z production cross sections and the W width are determined. Events with W {yields} {tau}{nu} decays are used to determine the ratio of the electroweak gauge coupling constants as a measure of lepton universality. Using W {yields} e{nu} and Z {yields} ee decays, the W boson mass is measured.
Date: October 1, 1997
Creator: Abbott, B.
Partner: UNT Libraries Government Documents Department

W and Z properties at the Tevatron

Description: The authors present recent results from CDF and D0 on W and Z production cross sections, the width of the W boson, {tau}-e universality in W decays, trilinear gauge boson couplings, and on the observation of Z {r{underscore}arrow} b{anti b}.
Date: January 26, 2000
Creator: Ellison, J.
Partner: UNT Libraries Government Documents Department

Measurement of the W Boson Production Asymmetry and W Boson Width at CDF

Description: We describe two measurements using 110 {+-} 7 pb{sup -1} of data collected by the CDF detector during 1992-95. The first is a new measurement of the charge asymmetry in the lepton rapidity range 0 < {vert_bar}y{sub l}{vert_bar} < 2.5 using W {yields} {mu}{nu}, e{nu} events. The asymmetry data constrain the ratio of d and u quark momentum distributions in the proton over the x range of 0.006 to 0.34 at Q{sup 2} {approx} M{sub W}{sup 2}. Although the data in the central rapidity region ({vert_bar}y{sub l}{vert_bar} < 1.1) are reproduced by modern parametrizations of parton distributions, there are differences in the high rapidity regions. The second measurement is a direct measurement of the W width using the lineshape of the transverse mass spectrum. The extracted W width is in good agreement with the standard model value, and with values obtained from the indirect method using the measured ratio of W and Z events.
Date: May 1, 1998
Creator: Bodek, A.
Partner: UNT Libraries Government Documents Department

A precision measurement of the Z{sup 0} lineshape parameters for the process Z{sup 0} {r_arrow} {tau}{sup +}{tau}{sup {minus}}

Description: In this dissertation, a measurement of the partial decay width of the process Z{sup 0} {r_arrow} {tau}{sup +}{tau}{sup {minus}} using data collected during 1993 and 1994 at the OPAL detector at CERN is described. The cross sections of this process at three center-of-mass energies near the Z{sup 0} resonance were determined, and from a fit to those cross sections, the mass of the Z{sup 0}, its total decay width and its partial decay width into {tau}{sup +}{tau}{sup {minus}} final states were determined as M{sub Z} = 91.183 {+-} 0.020 GeV, {Lambda}{sub tot} = 2.514 {+-} 0.018 GeV and {Lambda}{sub {tau}{tau}} = 84.54 {+-} 0.59 MeV. Using published results for M{sub Z}, and {Lambda}{sub tot} with higher accuracy, a value for the partial decay width of {Lambda}{sub {tau}{tau}} = 84.02 {+-} 0.20 MeV was obtained. Further using published results for the decay width of the Z{sup 0} into quark pair final states, the invisible decay width of the Z{sup 0} was determined as {Lambda}{sub inv} = 496.9 {+-} 4.1 MeV, and the number of neutrino generations was determined as N{sub {nu}} = 2.974 {+-} 0.025(exp) {+-} 0.007 (m{sub top}, M{sub Higgs}). All results were found to be in good agreement with the Standard Model predictions and were consistent with the assumption of lepton universality within the Standard Model framework.
Date: December 31, 1996
Creator: Lahmann, R.
Partner: UNT Libraries Government Documents Department

Semileptonic branching fraction and hadronic width of the B mesons in light of the new CLEO observation of b {r_arrow} {anti D}X

Description: This talk reports the latest CLEO observation of {anti D} production in b decays, which provides new insight of the QCD interactions in heavy quark systems. The observed B semileptonic branching fraction has been significantly lower than QCD expectations, as was confirmed by recent lepton-lepton correlation studies at various experiments that removed most of the model dependence in previous generation measurements. One possible explanation to accommodate this lepton shortage or a wider hadronic width of B mesons is that the process b {r_arrow} c{anti c}s contributes at a higher rate than expected. That explanation, however, predicts more charm production in than is observed. Using lepton tags in B events this analysis measures the fraction of b {r_arrow} {anti D}X in addition to b {r_arrow}DX. The first observation of {anti B} {r_arrow} {anti D}DX has profound implications to both experiment and theory.
Date: September 1, 1996
Creator: Wang, R.
Partner: UNT Libraries Government Documents Department

D0 results on W boson properties

Description: The D0 experiment collected {approx} 15 pb{sup -1} in run 1A (1992- 1993) and {approx}89 pb{sup -1} in run 1B (1994-1995) of the Fermilab Tevatron Collider using p{anti p} collisions at {radical}s = 1.8 TeV. Results from analyses of events with W and Z bosons are presented for the run 1B data samples. From W {yields} e{nu}, {mu}{nu} and Z {yields} ee, {mu}{mu} decays, the W and Z production cross sections and the W width are determined. Events with W {yields} {tau}{nu} decays are used to determine the ratio of the electroweak gauge coupling constants as a measure of lepton universality. Using W {yields} e{nu} and Z {yields} ee decays, the W boson mass is measured.
Date: June 1, 1997
Creator: Streets, K.
Partner: UNT Libraries Government Documents Department

CP conserving and CP violating asymmetries in e{sup +}e {r_arrow} t{anti t}{nu}{sub e}(anti{nu}{sub e}) at the NLC: Application to determining the Higgs width

Description: The polarization asymmetries of t, {anti t} quarks can be used in the reaction e{sup +}e {r_arrow} t{anti t}{nu}{sub e}anti({nu}{sub e}) to measure the Higgs width, in the Standard Model or in its extensions, and to search for non-standard CP violating phases. As an application of the CPT theorem the Higgs width is monitored through a CP-even, T{sub N}-odd, polarization asymmetry, B{sub y}. CP violation manifests through interference at tree graph level with the resonant Higgs amplitude. Consequently, the asymmetries are all quite sizable and can be in the range of 10--50% for a wide choice of the Higgs mass.
Date: July 1996
Creator: Atwood, David & Soni, Amarjit
Partner: UNT Libraries Government Documents Department

Axial couplings and strong decay widths of heavy hadrons

Description: We calculate the axial couplings of mesons and baryons containing a heavy quark in the static limit using lattice QCD. These couplings determine the leading interactions in heavy hadron chiral perturbation theory and are central quantities in heavy quark physics, as they control strong decay widths and the light-quark mass dependence of heavy hadron observables. Our analysis makes use of lattice data at six different pion masses, 227 MeV &lt; m{sub {pi}} &lt; 352 MeV, two lattice spacings, a = 0.085, 0.112 fm, and a volume of (2.7 fm){sup 3}. Our results for the axial couplings are g{sub 1} = 0.449(51), g{sub 2} = 0.84(20), and g{sub 3} = 0.71(13), where g{sub 1} governs the interaction between heavy-light mesons and pions and g{sub 2,3} are similar couplings between heavy-light baryons and pions. Using our lattice result for g{sub 3}, and constraining 1/m{sub Q} corrections in the strong decay widths with experimental data for {Sigma}{sub c}{sup (*)} decays, we obtain {Gamma}[{Sigma}{sub b}{sup (*)} {yields} {Lambda}{sub b} {pi}{sup {+-}}] = 4.2(1.0), 4.8(1.1), 7.3(1.6), 7.8(1.8) MeV for the {Sigma}{sub b}{sup +}, {Sigma}{sub b}{sup -}, {Sigma}{sub b}{sup *+}, {Sigma}{sub b}{sup *-} initial states, respectively. We also derive upper bounds on the widths of the {Xi}{sub b}{sup prime(*)} baryons.
Date: April 1, 2012
Creator: William Detmold, C.-J. David Lin, Stefan Meinel
Partner: UNT Libraries Government Documents Department

W Boson physics at the Fermilab Tevatron Collider

Description: Recent results from the CDF and D0 Experiments at the Fermilab Tevatron Collider are presented for the W and Z boson production cross sections, the W boson width, rare W boson decays, trilinear gauge boson couplings, and the W boson mass.
Date: August 1, 1998
Creator: Madaras, Ronald J.
Partner: UNT Libraries Government Documents Department

Spectroscopy and lifetime of bottom and charm hadrons

Description: There are several motivations for studying masses and lifetimes of the hadrons containing a heavy quark, either the bottom or the charm quark. First, the mass and the lifetime are fundamental properties of an elementary particle. Second, the spectroscopy of hadrons gives insights into the QCD potential between quarks. In particular, a symmetry exists for heavy hadrons when the heavy quark mass is taken to be infinite, providing a powerful tool to predict and understand properties of those heavy hadrons. Third, studies of the lifetimes of heavy hadrons probe their decay mechanisms. A measurement of the lifetime, or the total decay width, is necessary when the authors extract magnitudes of elements of the Kobayashi-Maskawa matrix. Again, in the limit of an infinite heavy quark mass things become simple and decay of a heavy hadron should be the decay of the heavy quark Q. This leads to a prediction that all hadrons containing the heavy quark Q should have the same lifetime, that of the quark Q. This is far from reality in the case of charm hadrons, where the D{sup +} meson lifetime is about 2.5 times longer than the D{sup 0} meson lifetime. Perhaps the charm quark is not heavy enough. The simple quark decay picture should be a better approximation for the bottom hadrons because of the larger b quark mass. On the experimental side, the measurements and knowledge of the heavy hadrons (in particular bottom hadrons) have significantly improved over the last decade, thanks to high statistics data accumulated by various experiments. The authors shall review recent developments in these studies in the remainder of this manuscript.
Date: May 15, 2000
Creator: Ukegawa, F.
Partner: UNT Libraries Government Documents Department

A relativistic chiral quark model for pseudoscalar emission from heavy mesons

Description: The amplitudes for one-pion mediated transitions between heavy meson excited states are obtained in the framework of the relativistic chiral quark model. The effective coupling constants to pions and the decay widths of excited heavy mesons with l {&lt;=} 2 for non-radially excited, and the l=0 radially excited mesons are presented for both charmed and beauty mesons. They also discuss the allowed decays of strange excited heavy mesons by emission of a K-meson.
Date: September 1, 1998
Creator: Goity, J. L. & Roberts, W.
Partner: UNT Libraries Government Documents Department

Preliminary results for two pion resonances in D{sup +} and D{sup +}{sub s} {r_arrow} {pi}{sup {minus}}{pi}{sup +}{pi}{sup +} from Fermilab experiment E-791

Description: In this paper the authors present preliminary results of a coherent amplitude analysis of three-pion decays of charm mesons. The analysis includes a greater number of possible resonant states than in previous analyses, and produces masses and Breit-Wigner widths of the isoscalar resonances f{sub 0} (980) and f{sub 0} (1370) with better precision than previous measurements. They also present preliminary results for the mass and width of the low lying f{sub o} (400), sometimes called the {sigma} meson.
Date: July 6, 2000
Creator: Stefanski, Raymond J.
Partner: UNT Libraries Government Documents Department