The colour-singlet technipion<i>P</i><sup>0</sup>and the recent experimental results at LEPII

Yue, C. X.; Lu, G. R.; Qingjun, Xu; Li, Guoli

doi:10.1088/0954-3899/27/5/307

Cited by 6 publications

(6 citation statements)

References 15 publications

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“…A similar enhancement can be reached in supersymmetric models were R-parity is violated [302]. In topcolour-assisted technicolour theories the branching ratio for t → cW + W − can reach values up to 10 −3 [303]. Since the SM predictions for FCNC interactions have much smaller rates, they are useful probes for new physics beyond the SM.…”

Section: Fcnc Decaysmentioning

confidence: 64%

Top quark physics in hadron collisions

Wagner¹

2005

Rep. Prog. Phys.

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The top quark is the heaviest elementary particle observed to date. Its large mass makes the top quark an ideal laboratory to test predictions of perturbation theory concerning heavy quark production at hadron colliders. The top quark is also a powerful probe for new phenomena beyond the Standard Model of particle physics. In addition, the top quark mass is a crucial parameter for scrutinizing the Standard Model in electroweak precision tests and for predicting the mass of the yet unobserved Higgs boson. Ten years after the discovery of the top quark at the Fermilab Tevatron top quark physics has entered an era where detailed measurements of top quark properties are undertaken. In this review article an introduction to the phenomenology of top quark production in hadron collisions is given, the lessons learned in Tevatron Run I are summarized, and first Run II results are discussed. A brief outlook to the possibilities of top quark research a the Large Hadron Collider, currently under construction at CERN, is included.PACS numbers: 14.65.Ha Summary and outlook 79Top quark physics in hadron collisions 4 IntroductionThe top quark is the by far heaviest of the six fundamental fermions in the Standard Model (SM) of particle physics. Its large mass made the search for the top quark a long and tedious process, since accelerators with high centre-of-mass energies are needed. In 1977 the discovery of the bottom quark indicated the existence of a third quark generation, and shortly thereafter the quest for the top quark began. Searches were conducted in electron-positron (e + e − ) and protonantiproton (pp) collisions during the 1980s and early 1990s. Finally, in 1995 the top quark was discovered at the Fermilab Tevatron pp collider. Subsequently, its mass was precisely measured to be M top = (178.0 ± 4.3) GeV/c 2 [1]. The relative precision of this measurement (2.4%) is better than our knowledge of any other quark mass. The top quark is about 40 times heavier than the second-heaviest quark, the bottom quark. Its huge mass makes the top quark an ideal probe for new physics beyond the SM.It remains an open question to particle physics research whether the observed mass hierarchy is a result of unknown fundamental particle dynamics. It has been argued that the top quark could be the key to understand the dynamical origin of how particle masses are generated by the mechanism of electroweak symmetry breaking, since its mass is close to the energy scale at which the break down occurs (vacuum expectation value of the Higgs field = 246 GeV) [2]. The most favoured framework to describe electroweak symmetry breaking is the Higgs mechanism. The masses of the Higgs boson, the W boson and the top quark are closely related through higher order corrections to various physics processes. A precise knowledge of the top quark mass together with other electroweak precision measurements can therefore be used to predict the Higgs boson mass. At present, top quarks can only be directly produced at the Tevatron. The physics results of the Tevat...

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Section: Fcnc Decaysmentioning

confidence: 64%

Top quark physics in hadron collisions

Wagner¹

2005

Rep. Prog. Phys.

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“…FWE in these decay modes will be studied within the SM (in the case of t → cW W ) and in the context of the type III Two Higgs Doublet Model (in both t → cW W and t → cZZ), which admits flavor changing neutral currents (FCNC) at the tree-level. The three-body top decays t → cW W, bW Z, cZZ have been considered before, without including FWE, in the SM [7,8,9], in 2HDM's [9,10,11,12,13], in a generic formalism including scalar, vector or fermion exchanges [14] and in topcolor-assisted Technicolor model [15]. In addition, the top decays t → bW h 0 and t → bW A 0 have been analyzed in the context of a general 2HDM [16].…”

Section: Introductionmentioning

confidence: 99%

Width effects on near threshold decays of the top quarkt→cWW,cZZand of neutral Higgs bosons

et al. 2005

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The nonzero widths of heavy particles become significant when they appear in the final state of any decay occurring just around its kinematical threshold. To take into account such effects, a procedure, called the convolution method, was proposed by Altarelli, Conti and Lubicz. We expand their study which included only threshold effects for t → bW Z in the standard model. We discuss finite width effects in the three body decays t → cW W, cZZ and A 0 (h 0 ) → tbW in the type III version of a two Higgs doublet model. In particular, we find a substantial enhancement in the decay t → cZZ, which brings its branching ratio to BR(t → cZZ) ∼ 10 −3 , and in the decay A 0 → tbW , which, unlike the h 0 case, becomes competitive with the A 0 two-body decay modes.

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“…A few recent studies on the other FCNC processes predicted by the topcolor model can be found in Ref. [15].…”

Section: T → Cφmentioning

confidence: 99%