6,324 research outputs found

    Top quark spin in ep collision

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    We discuss the degree of spin polarization of single top quarks produced via WgWg fusion process in epep collision at TESLA+HERAp and CLIC+LHC energies s=1.6\sqrt{s}=1.6 and 5.3 TeV. A description on how to combine the cross sections of e+b→tνˉe^{+}b\to t\bar{\nu} and e+g→tbˉνˉe^{+}g\to t\bar{b}\bar{\nu} processes is given. e+e^{+}-beam direction is taken to be the favorite top quark spin decomposition axis in its rest frame and it is found to be comparable with the ones in pppp collision. It is argued that theoretical simplicity and experimental clearness are the advantage of epep collision.Comment: 2 eps figure

    Top Quark Spin Polarization in ep Collision

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    We discuss the degree of spin polarization of single top quarks produced via WgWg fusion process in epep collision at TESLA+HERAp and CLIC+LHC energies s=1.6\sqrt{s}=1.6 and 5.3 TeV. For eb→tνˉeb \to t \bar{\nu} subprocess we show that the top quark spin is completely polarized when the spin basis is chosen in the direction of the incoming positron beam in the rest frame of top quark. A description on how to combine the cross sections of e+b→tνˉe^{+}b\to t\bar{\nu} and e+g→tbˉνˉe^{+}g\to t\bar{b}\bar{\nu} processes is given. e+e^{+}-beam direction is taken to be the favorite top quark spin decomposition axis in its rest frame and it is found to be comparable with the ones in pppp collision. It is argued that theoretical simplicity and experimental clearness are the advantage of epep collision.Comment: Revised version of Phys. Rev. D69 (2004)03401

    Top Quark Spin Polarization in e \gamma Collision

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    We investigate the degree of spin polarization of single top quarks in the eγe\gamma collision via the process e+γ→tbˉνeˉe^{+} \gamma \to t \bar{b} \bar{\nu_{e}} with center of mass energies s\sqrt{s}=0.5, 1 and 1.5 TeV of the parental linear e+e−e^{+}e^{-} collider. Dominant spin fractions and spin asymmetries for the various top quark spin bases are investigated. We show that e+e^{+}-beam direction is the favorite top quark spin decomposition axis. It is found to be comparable with the ones in pppp and epep collisions.Comment: 5 pages, 3 figure

    Top quark and Electroweak measurements at the Tevatron

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    We present recent preliminary measurements at the Tevatron of t-tbar and single top production cross section, top quark mass and width, top pair spin correlations and forward-backward asymmetry. In the electroweak sector, we present the Tevatron average of the W boson width, and preliminary measurements of the W and Z forward-backward asymmetries and WZ, ZZ diboson production cross sections. All measurements are based on larger amount of collision data than previously used and are in agreement with the standard model.Comment: 6 pages, 6 figures; In proceedings of the 16th International Symposium on Particles, Strings and Cosmology, Valencia (Spain) 201

    Top quark properties

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    The multi-purpose experiments at CERN's Large Hadron Collider have a very rich programme in top quark physics. The large amount of data allows for measuring the top quark properties with an unprecedented precision. This document presents some of the properties that have been measured using top quark pair events produced in proton-proton collisions with a centre-of-mass energy of 13 TeV. The focus lies on the measurements of the colour flow, the charge asymmetry and spin correlations in top quark pair events.Comment: 5 pages, 6 figures, TOP2018 conference proceeding
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