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Next we consider the topquark momentum (
)
distribution
near
threshold [8,9].
It has been shown that experimentally it will be possible to reconstruct
the topquark momentum
from its decay products with
reasonable resolution and detection efficiency.
Fig. 4.2(a)
shows a comparison of reconstructed top momenta (solid circles)
with that of generated ones (histogram),
where the events are generated by a Monte Carlo generator
and are reconstructed after going through detector simulators
and selection cuts; see Subsection 4.2.4 for
details.
The figure demonstrates that the agreement is fairly good.
Theoretically, the topquark momentum distribution is given by
The
distribution is thus governed by the momentumspace
wave functions of the resonances.
By measuring the momentum distribution, essentially we measure
(a superposition of) the wave functions of the toponium resonances.
Shown in Fig. 4.2(b) are the top momentum distributions for various
energies.
Figure:
(a) Reconstructed momentum distribution (solid circles) for the
leptonplus4jet mode, compared with the generated distribution (histogram).
The Monte Carlo events were generated with
and m_{t} = 150 GeV [5].
(b) Topquark momentum distributions
for various c.m. energies measured from
the lowest lying resonance,
,
taking
and m_{t} = 175 GeV.

One may also vary the magnitude of
and confirm that the
distribution is indeed sensitive to the resonance wave functions
[8,9].
Hence, the momentum distribution provides information independent of that
from the total cross section.
Next: ForwardBackward Asymmetry
Up: 4.2.3 Observables
Previous: Total Cross Section
ACFA Linear Collider Working Group
EMail:acfareport@acfahep.kek.jp