A Top Event

The top quark --> a bottom quark and W+;

then the W+ --> e+ and a neutrino, and
the bottom quark (which emerged as a neutral anti-B meson) decays into jet 4.

The antitop quark --> an antibottom quark and W-;

then the W- --> an anti-up quark (jet 2 or 3) and a down quark (jet 3 or 2), and
the antibottom quark (neutral B meson) decays into jet 1.

(We cannot tell from jets 2 and 3 which is the anti-up quark and which is the down quark.)

Both the bottom quark and the antibottom quark have long enough lifetimes and enough energy to travel a visible distance before they decay. The bottom went 2.2 mm and the antibottom went 4.5 mm. Because both quarks emerged as neutral particles, neither left tracks until they decayed.

Notice that the neutrino left no tracks; its presence was inferred by the missing momentum and energy.

    You can see an ANIMATION of this top event.    
    A frame-by-frame EXPLANATION of above animation.    
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