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Title: Associated production of the top-pions and single top at hadron colliders

Abstract

In the context of topcolor-assisted technicolor (TC2) models, we study the production of the top-pions {pi}{sub t}{sup 0,{+-}} with single top quark via the processes pp{yields}t{pi}{sub t}{sup 0}+X and pp{yields}t{pi}{sub t}{sup {+-}}+X, and discuss the possibility of detecting these new particles at Tevatron and LHC. We find that it is very difficult to observe the signals of these particles via these processes at Tevatron, while the neutral and charged top-pions {pi}{sub t}{sup 0} and {pi}{sub t}{sup {+-}} can be detecting via considering the same sign top pair ttc event and the ttb (or ttb) event at LHC, respectively.

Authors:
; ; ;  [1]
  1. Department of Physics, Liaoning Normal University, Dalian 116029 (China)
Publication Date:
OSTI Identifier:
20774635
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevD.73.015006; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CERN LHC; COLOR MODEL; FERMILAB TEVATRON; PARTICLE IDENTIFICATION; PARTICLE PRODUCTION; PIONS; T QUARKS

Citation Formats

Yue Chongxing, Zong Zhengjun, Xu Lili, and Chen Jianxing. Associated production of the top-pions and single top at hadron colliders. United States: N. p., 2006. Web. doi:10.1103/PhysRevD.73.015006.
Yue Chongxing, Zong Zhengjun, Xu Lili, & Chen Jianxing. Associated production of the top-pions and single top at hadron colliders. United States. doi:10.1103/PhysRevD.73.015006.
Yue Chongxing, Zong Zhengjun, Xu Lili, and Chen Jianxing. Sun . "Associated production of the top-pions and single top at hadron colliders". United States. doi:10.1103/PhysRevD.73.015006.
@article{osti_20774635,
title = {Associated production of the top-pions and single top at hadron colliders},
author = {Yue Chongxing and Zong Zhengjun and Xu Lili and Chen Jianxing},
abstractNote = {In the context of topcolor-assisted technicolor (TC2) models, we study the production of the top-pions {pi}{sub t}{sup 0,{+-}} with single top quark via the processes pp{yields}t{pi}{sub t}{sup 0}+X and pp{yields}t{pi}{sub t}{sup {+-}}+X, and discuss the possibility of detecting these new particles at Tevatron and LHC. We find that it is very difficult to observe the signals of these particles via these processes at Tevatron, while the neutral and charged top-pions {pi}{sub t}{sup 0} and {pi}{sub t}{sup {+-}} can be detecting via considering the same sign top pair ttc event and the ttb (or ttb) event at LHC, respectively.},
doi = {10.1103/PhysRevD.73.015006},
journal = {Physical Review. D, Particles Fields},
number = 1,
volume = 73,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Single production of top quarks at hadron colliders via {ital gW} fusion is examined as a probe of possible anomalous chromomagnetic and/or chromoelectric moment type couplings between the top quark and gluons. We find that this channel is far less sensitive to the existence of anomalous couplings of this kind than is the usual production of top quark pairs by {ital gg} or {ital q{bar q}} fusion. The contribution to the cross section and various kinematical distributions from anomalous couplings with interesting magnitudes is essentially hidden by the present theoretical uncertainties in the calculation. This result is found to holdmore » at both the Fermilab Tevatron as well as the CERN LHC, although somewhat greater sensitivity for anomalous couplings in this channel is found at the higher energy machine. {copyright} {ital 1996 The American Physical Society.}« less
  • CP-nonconserving effects in the reaction p{bar p}{r_arrow}t{bar b}+X{r_arrow}W{sup +}b{bar b}+X, driven by the supersymmetric CP-odd phase of the top squark trilinear soft breaking term arg(A{sub t}), are studied. We discuss the CP-nonconserving effects in both production and the associated decay amplitudes of the top quark. We find that, within a plausible low energy scenario of the MSSM and keeping the neutron electric dipole moment below its current limit, a CP-violating cross-section asymmetry as large as 2{minus}3{percent} can arise if some of the parameters lie in a favorable range. A partial rate asymmetry originating only in the top quark decay t{r_arrow}W{supmore » +}b is found to be, in general, below the 0.1{percent} level which is somewhat smaller than previous claims. For a low tan{beta} of order one the decay asymmetry can reach at the most {approximately}0.3{percent}. This (few) percent level overall CP-violating signal in p{bar p}{r_arrow}t{bar b}+X{r_arrow}W{sup +}b{bar b}+X might be within the reach of the future 2(4) TeV p{bar p} Fermilab Tevatron collider that may be able to produce {approximately}10000 ({approximately}30000) such t{bar b} events with an integrated luminosity of 30 fb{sup {minus}1}. In particular, it may be used to place an upper bound on arg(A{sub t}) if indeed arg({mu}){r_arrow}0, as implied from the present experimental limit on the neutron electric dipole moment. The partial rate asymmetry in the top quark decay ({approximately}few{times}10{sup {minus}3}) may also be within the reach of the CERN LHC with {approximately}10{sup 7} pairs of t{bar t} produced, provided detector systematics are sufficiently small. We also show that if the GUT scale universality of the soft breaking trilinear A terms is relaxed, then the phases associated with arg(A{sub u}) and arg(A{sub d}) can take values up to {approximately}few{times}10{sup {minus}1} even with squarks and gluino masses of several hundred GeV{close_quote}s without contradicting the experimental limit on the neutron electric dipole moment. {copyright} {ital 1997} {ital The American Physical Society}« less
  • We calculate single top-quark production at hadron colliders via the chromo-magnetic flavor-changing neutral current couplings {bar t}cg and {bar t}ug. We find that the strength for the anomalous {bar t}cg({bar t}ug) coupling may be probed to {kappa}{sub c}/{Lambda}=0.092thinspTeV{sup {minus}1} ({kappa}{sub u}/{Lambda}=0.026thinspTeV{sup {minus}1}) at the Fermilab Tevatron with 2thinspfb{sup {minus}1} of data and {kappa}{sub c}/{Lambda}=0.013thinspTeV{sup {minus}1} ({kappa}{sub u}/{Lambda}=0.0061thinspTeV{sup {minus}1}) at the CERN LHC with 10thinspfb{sup {minus}1} of data. The two couplings may be distinguished by a comparison of the single top signal with the direct top and top decay signals for these couplings. {copyright} {ital 1998} {ital The American Physical Society}
  • Single-top-quark production probes the charged-current weak interaction of the top quark, and provides a direct measurement of the CKM matrix element V{sub tb}. We perform two independent analyses to quantify the accuracy with which the W-gluon fusion (gq{r_arrow}t{bar b}q) and q{bar q}{r_arrow}t{bar b} signals can be extracted from the backgrounds at both the Fermilab Tevatron and the CERN LHC. Although perturbation theory breaks down at low transverse momentum for the W-gluon fusion {bar b} differential cross section, we show how to obtain a reliable cross section integrated over low {bar b} transverse momenta up to a cutoff. We estimate themore » accuracy with which V{sub tb} can be measured in both analyses, including theoretical and statistical uncertainties. We also show that the polarization of the top quark in W-gluon fusion can be detected at the Fermilab Tevatron and the CERN LHC. {copyright} {ital 1998} {ital The American Physical Society}« less
  • CP-nonconserving effects in the reaction pp-bar-->tb-bar+X--> W{sup +}bb-bar+X, driven by the supersymmetric CP-odd phase of the top squark trilinear soft breaking term arg(A{sub t}), are studied. We discuss the CP-nonconserving effects in both production and the associated decay amplitudes of the top quark. We find that, within a plausible low energy scenario of the MSSM and keeping the neutron electric dipole moment below its current limit, a CP-violating cross-section asymmetry as large as 2-3% can arise if some of the parameters lie in a favorable range. A partial rate asymmetry originating only in the top quark decay t --> W{supmore » +}b is found to be, in general, below the 0.1% level which is somewhat smaller than previous claims. For a low tan beta of order one the decay asymmetry can reach at the most {approx} 0.3%. This (few) percent level overall CP-violating signal in pp-bar --> tb-bar + X --> W{sup +}bb-bar + X might be within the reach of the future 2(4) TeV pp-bar Fermilab Tevatron collider that may be able to produce {approx} 10000 ({approx} 30000) such tb-bar events with an integrated luminosity of 30 fb{sup -1}. In particular, it may be used to place an upper bound on arg(A{sub t}) if indeed arg({mu}) --> 0, as implied from the present experimental limit on the neutron electric dipole moment. The partial rate asymmetry in the top quark decay ({approx} few x 10{sup -3}) may also be within the reach of the CERN LHC with {approx} 10{sup 7} pairs of tt-bar produced, provided detector systematics are sufficiently small. We also show that if the GUT scale universality of the soft breaking trilinear A terms is relaxed, then the phases associated with arg(A{sub u}) and arg(A{sub d}) can take values up to {approx} few x 10{sup -1} even with squarks and gluino masses of several hundred GeV's without contradicting the experimental limit on the neutron electric dipole moment.« less