Strange particle production in hadronic Z{sup 0} decays Page: 69 of 82
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113
Chapter 7
The Flavor and Quark-Jets Analysisand the c-quark-enriched (njg = 1,2) samples with respect to the uds-quark-enriched
(n,;i = 0) sample. For the A0 (+,0) samples, a possible enhancement of the production
in the c-quark-enriched (n,ig = 1,2) sample with respect to those in the other two
samples is seen. We therefore performed a complete unfolding of the three samples in
order to obtain the production spectra for the light, c, and b quark samples.7.2.1 The Unfolding Matrix
7.1 Introduction
In this chapter, the flavor tagging and quark-jet tagging techniques described in Section
5.4 are used to further explore the hadronization process. First, the analysis in the
preceding chapter is applied to flavor-tagged samples, and differences in production are
observed. These spectra are "unfolded" to obtain the first measurements of K and
A0+Ai production in light (u, d, s), c, and b-quark events at the Z0. Next, the quark-
tagging techniques are used to examine differences in A0 production for light quark and
anti-quark jets, and to make the first measurements of the q - A0 and the q -- A0
fragmentation functions.
7.2 Spectra in uds, c, and b-quark Events
Using the techniques discussed in Chapter 5, the data set was divided into three flavor-
enriched subsets; this resulted in a uds-enriched sample of 53526 events, a c-enriched
sample of 22648 events, and a b-enriched sample of 14039 events. For each sample, the
V0 candidates were binned in and the analysis described in Chapter 6 was repeated.
The K, binning used was identical to that described in the previous chapter; the
A0/P0's were binned in wider a-bins, which then typically required 3 gaussians to
describe the peak adequately. When we treat them in the same manner as was described
in the last chapter, simply correcting for the reconstruction efficiency (which to a good
approximation is independent of the event flavor), we arrive at the production spectra
shown in Figure 7.1. Clear differences in production among the three samples are
observed. For the K0, production is enhanced in the b-quark-enriched (n.,i = 3+)The expected number of particles of type X per i-tagged event n; (i = 1,2,3 for
n,ig = 0,1 - 2,3+ resp.), can be related to the true number per j-flavor event mi
(j = uds, c, b) by the three linear equations:(7.1)
n() = E i Egmji(3),
where it is convenient to express the matrix
Eii = fi~11bi,( )R( ) (7.2)
Yk fkEik
in terms of the V0 reconstruction efficiency R( ) (discussed in the last chapter), the
fraction of hadronic Z events decaying into quark type j
f = ",(7.3)
Nzo-.ac
an event-tagging efficiency matrix(7.4)
j
where N .. is the number of reconstructed j-flavor events that are in the i-tagged
sample and NJ is the total number of reconstructed j-flavor events, and a bias term
bi(e)= X (e)/N; . (7.5)
Here, Xj.( ) is the number of reconstructed particles of species X from quark flavor
j that are found in the i-tagged sample. For the above, and all following equations,
there is no implicit summation over repeated indices.
Note the definition of the Tag Purity (Pi) is related to the above matrices as follows:
p= . (7.6)
il'k fk Eik114
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Baird, K.G. III. Strange particle production in hadronic Z{sup 0} decays, report, April 1, 1996; Menlo Park, California. (https://digital.library.unt.edu/ark:/67531/metadc665661/m1/69/: accessed May 6, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.