Search for Charm in 250 GeV/c $pi$$sup -$p Interactions Page: 2 of 6
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-2-
+ ii + X
B+ 5 +X(1)
where Bc and Mc stand for charmed baryons and mesons, respect-
ively, and X stands for anything else that may be produced. The
decay nodes included were:
- +
Bo A (A) + +
-D + A (h) + m + n
')c S + n
MHoNs +II+ +5
and their antiparticles.
Theoretical estimates of charm-anticharm production would
indicate that the cross-section is lower than the sensitivity
of this experiment. However, an experimental estimate can be
mado by comparing with the dd production cross section which is
cif the order of 1 pb'. This experiment is unique in ihat the
4s geometry of the.chamber allows us to identify A's, thus mak-
ing us sensitive to decay modes not detected by a recent counter
experiment. Our center of mass energy of 21.7 GeV allows de-
teetion of higher masses than is possible in lower energy ex-
periments . We therefore feel that these results, although
statistically limited, are important.
Tho data for this study are the preliminary results of a
46,000 picture exposure of v p at 250 GeV/c. In about 40% ofthis film, 795 events have obtained fits to neutral strange
particle hypotheses. These particles have been analyzed using
the CERN hYDRA geometry-kinematics system. Of these events,
135 contained two or more fitted neutral strange particles.
The cross section for these events has been determined by
weighting the number of events found by the following factors'
a) scanning efficiencies for finding tho primary
vertex and for finding Vee decays
b) detection efficiencies for missing close-In
Vecs (all Vees closer than 10 cm to the
primary vertex wore eliminated from the
sample due to large inefficiencies in this
region)
c) corrections for neutzel" decaying outside
the chamber
d) measurement and fitting efficiencies (through
the HYDRA system)
e) branching ratios for observable decays cf
xs 's, A's and A
f) the microbarn equivalent, determined from a
measurement of the total cross section.1
The resultant inclusive cross sections for production of
x K , x4n, REX, and AK are given in Table I. The effective
mass distributions for thrts strange particle pairs are shown
in Fig. 1. In each case, the dominant feature is peaking near
the low mass threshold for the production of tho pair. Such
threshold enhancements may indicate the existence of non-charmed
two strange particle clusters.-3-
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Harris, R.; Bogert, D. & Hanft, R. Search for Charm in 250 GeV/c $pi$$sup -$p Interactions, article, January 1, 1975; Batavia, Illinois. (https://digital.library.unt.edu/ark:/67531/metadc863301/m1/2/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.