Measurement of $$b\bar{b}$$ Production Correlations, $$B^0 \bar{B}^0$$ Mixing, and a Limit on the CP Violating Parameter $$\epsilon_B$$ in $$p\bar{p}$$ Collisions at CDF
- Yale U.
In $$p\bar{p}$$ collisions at $$\sqrt{s}$$ = 1.8 TeV, $$b\bar{b}$$ quark pairs are produced with a significant cross section. High momentum muons from semileptonic decays of bottom quarks can provide a data set for the studies of $$b\bar{b}$$ physics. Muons from bottom decays are distinguishable from others by their displaced trajectories resulting from the long lifetimes of bottom hadrons. In this thesis, we have presented a measurement of correlated $$b\bar{b}$$ cross-sections, $$\mu - \mu$$, correlations, and the average $$B^O \bar{B}^0$$ mixing parameter $$\bar{X}$$, and a limit on the CP violating parameter $$\epsilon_B$$, using dimuon events from $$b\bar{b}$$ double semileptonic decays. The data used were taken with the CDF detector during the 1992-1993 run of the Fermilab Tevatron and represent an integrated luminosity of 17.4 ± 0.6 $$pb^{-1}$$. The results concerning $$b\bar{b}$$ production correlations are compared to predictions of next-to-leading (NLO) order QCD computations. The normalization of the bb cross section is found to be higher than the theory prediction, which could be explained by adjusting the QCD input parameters. The distributions of the azimuthal opening angle and the muon transverse momentum obtained from the studies of $$\mu - \mu$$, correlations show reasonable agreement between data and NLO QCD theory. A comparison between the number of $$b\bar{b}$$ events with like-sign and opposite-sign dimuons yields a value of the $$B^O \bar{B}^0$$ mixing parameter X = 0.131 ± 0.020(stat) ± O.016(sys). In addition, the asymmetry between the number of $$\mu^+ \mu+$$ and $$\mu^+\mu^+$$,events is used to place a limit on the real part of $$\epsilon_B$$ which gives rise to CP violation in $$B^O \bar{B}^0$$ mixing.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1422808
- Report Number(s):
- FERMILAB-THESIS-1996-25; UMI-96-36110; 429058
- Country of Publication:
- United States
- Language:
- English
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