New Results from High Energy e + e - Experiments

Kamae, T.

doi:10.1007/978-3-642-74136-4_10

Cited by 1 publication

(1 citation statement)

References 55 publications

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“…An example of this approach is illustrated in Fig. 2, which shows the measured hadronic event rate from experiments at three different e +e -colliders [7] (this rate is normalized to the measured rate of e + e _ → µ + µ-events to reduce sys tematic uncertainties). The data points agree well with a prediction which assumes that only the first five quark flavours are produced, and disagree with a prediction that includes the top quark.…”

Section: Searches At E + E _ Collidersmentioning

confidence: 99%

The Top Quark

Lella¹

1990

Europhys. News

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The Standard Model requires the existence of a sixth or top quark to suppress transitions of the fifth or beauty quark found in 1974. Prospects for its discovery are considered in the light of recent results showing that the top's mass exceeds 89 GeV/c2.The quark model was proposed in 1964 [1] to describe the large number of strongly Interacting particles (hadrons) produced at high-energy accelerators in terms of a small number of elemen tary constituents. In its original formula tion, the model needed three quarks of spin 1/2 and baryon number 1/3: the u-quark, with electric charge +2/3 (in units of the proton charge), and two quarks with electric charge -1/3, na med d and s. These quarks together with their antiquarks u, d and s were sufficient to describe all known baryons and mesons, the baryons consisting of three quarks and the mesons of a quarkantiquark pair. The s and s quarks were needed to account for the strange ha drons, such as the K-mesons and the hyperons (A, Z, E, Ω, etc.).In the quark model, the weak decay of a hadron is described in terms of the weak decay of one of the constituent quarks. For example, the |3-decay of the neutron, which is a ddu system, is the result of the decay d → ue-ve of one of the two d-quarks. The final quark sys tem, duu, is the proton. Similarly, the β-decay of the A hyperon (a uds system) is described in terms of quark decay s → ue~ve, resulting in the observed decay A → pe-ve. Fourth and Fifth QuarksThe existence of weak s → u transi tions implied the occurrence of s -d transitions to second order in the weak interaction, as a result of an interme diate transition to a u-quark state (s → u, u → d). Such s -d transitions would result, for example, in the decays K° → µ + µ-or K+ → π + e + e _ which had not been observed experimentally in the 60's (such decays were later measured to occur at very low rates, representing

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Section: Searches At E + E _ Collidersmentioning

confidence: 99%

The Top Quark

Lella¹

1990

Europhys. News

View full text Add to dashboard Cite

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New Results from High Energy e + e - Experiments

Cited by 1 publication

References 55 publications

The Top Quark

The Top Quark

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