Monte Carlo simulation of jets in the upsilon and <i>t</i>-quarkonium regions

Cho-Kuen Ng

doi:10.1103/PhysRevD.33.3246

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Monte Carlo simulation of jets in the upsilon and t-quarkonium regions

Cho-Kuen Ng

Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, Illinois 61801

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Phys. Rev. D 33, 3246 – Published 1 June, 1986

DOI: https://doi.org/10.1103/PhysRevD.33.3246

Abstract

We apply Webber’s QCD branching Monte Carlo model to study the properties of jets produced in upsilon decay and the nearby continuum $e^{+}$ $e^{-}$ annihilations. In general, agreement between the Monte Carlo simulation and data is obtained. More baryons are produced in upsilon decay than in the continuum annihilation because there are more heavy colorless clusters in the configuration of upsilon decay. We then investigate the various decay mechanisms of t-quarkonium. The heavy-particle spectra are found to be quite different for various decay modes of t-quarkonium.

References (20)

R. Odorico, Nucl. Phys. B 172, 157 (1980); G. Fox and S. Wolfram, ibid B 168, 285 (1980); T. Gottschalk, ibid B 214, 201 (1983).
G. Marchesini and B. R. Webber, Nucl. Phys. B 238, 1 (1984); B. R. Webber, ibid, B 238, 492 (1984).
For a review, see Yu. L. Dokshitzer, D. I. Dyakonov and S. I. Troyan, Phys. Rep. 58, 269 (1980).
A. H. Mueller, Phys. Lett. 104 B, 161 (1981); A. Bassetto, M. Ciafaloni, G. Marchesini and A. H. Mueller, Nucl. Phys. B 207, 189 (1982); A. Bassetto, M. Ciafaloni, and G. Marchesini, Phys. Rep. 100, 201 (1984); B. I. Ermolaev and V. S. Fadin, Pis'ma Zh. Eksp. Teor. Fiz. 33, 285 (1981) [JETP Lett. 33, 269 (1981)]; Yu. L. Dokshitzer, V. S. Fadin and V. A. Khoze, Phys. Lett. 115 B, 242 (1982); Z. Phys. C 15, 325 (1983) 18, 37 (1983); V. S. Fadin, Yad. Fiz. 37 408 (1983) [Sov. J. Nucl. Phys. 37, 245 (1983)].
T. Gottschalk, lectures given at the 1983 Kupari-Dubrovnik Summer School, Yugoslavia, 1983 (unpublished); Caltech Report No. Calt-68-1075 (unpublished), and references therein.
S. Behrends et al., Phys. Rev. D 31, 2161 (1985).
G. Altarelli and G. Parisi, Nucl. Phys. B 128, 298 (1977).
D. Amati and G. Veneziano, Phys. Lett. 83 B, 87 1979).
P. Mazzanti, R. Odorico and V. Roberto, Nucl. Phys. B 193, 541 (1981); Cho-Kuen Ng, Phys. Rev. D 31, 469 (1985).
Particle Data Group, Rev. Mod. Phys. 56, S1 (1984).
TASSO Collaboration, M. Althoff et al., Z. Phys. C 17, 5 (1983); TASSO Collaboration, R. Brandelik et al., Phys. Lett. 108 B, 71 (1982); , ibid. 94 B, 91 (1980); , ibid. 105 B, 75 (1981).
R. Cabenda, Ph.D. thesis, Cornell University, 1982.
R. D. Field, Phys. Lett. 135 B, 203 (1984).
H. Albrecht et al., Phys. Lett. 102 B, 291 (1981).
CLEO detects more charged pions than predicted, especially at large z. One might ask whether this indicates a problem with the theory, or an unsually high data set. We thus turn to comparison with other experiments, where the continuum two-jet cross section has been extensively studied. At 34 GeV, the agreement between TASSO and our Monte Carlo results is within 15% for, say, z >= 0.65. Hence there is no serious problem with the calculations at large z.
Using Webber's original set of parameters which contains a lower $Q_{0}$ value does not change this fact very much.
UA1 Collaboration, G. Arnison et al., Phys. Lett. 147 B, 493 (1984).
J. H. Kühn and S. Ono, Z. Phys. C 21, 395 (1984); ibid. 24, 404(E) (1984); J. H. Kühn and K. H. Streng, Nucl. Phys. B 198, 71 (1982); A. D. Martin, in New Particles 1985, proceedings of the Conference on New Particles, Madison, 1985, edited by V. Barger, D. Klein, and F. Halzen (World-Scientific, Singapore, in press).
S. Godfrey and N. Isgur, Phys. Rev. D 32, 189 (1985).
A. De Rújula, Howard Georgi and S. L. Glashow, Phys. Rev. D 12, 147 (1975).

[c1] R. Odorico, Nucl. Phys. B 172, 157 (1980); G. Fox and S. Wolfram, ibid B 168, 285 (1980); T. Gottschalk, ibid B 214, 201 (1983).

[c2] G. Marchesini and B. R. Webber, Nucl. Phys. B 238, 1 (1984); B. R. Webber, ibid, B 238, 492 (1984).

[c3] For a review, see Yu. L. Dokshitzer, D. I. Dyakonov and S. I. Troyan, Phys. Rep. 58, 269 (1980).

[c4] A. H. Mueller, Phys. Lett. 104 B, 161 (1981); A. Bassetto, M. Ciafaloni, G. Marchesini and A. H. Mueller, Nucl. Phys. B 207, 189 (1982); A. Bassetto, M. Ciafaloni, and G. Marchesini, Phys. Rep. 100, 201 (1984); B. I. Ermolaev and V. S. Fadin, Pis'ma Zh. Eksp. Teor. Fiz. 33, 285 (1981) [JETP Lett. 33, 269 (1981)]; Yu. L. Dokshitzer, V. S. Fadin and V. A. Khoze, Phys. Lett. 115 B, 242 (1982); Z. Phys. C 15, 325 (1983) 18, 37 (1983); V. S. Fadin, Yad. Fiz. 37 408 (1983) [Sov. J. Nucl. Phys. 37, 245 (1983)].

[c5] T. Gottschalk, lectures given at the 1983 Kupari-Dubrovnik Summer School, Yugoslavia, 1983 (unpublished); Caltech Report No. Calt-68-1075 (unpublished), and references therein.

[c6] S. Behrends et al., Phys. Rev. D 31, 2161 (1985).

[c7] G. Altarelli and G. Parisi, Nucl. Phys. B 128, 298 (1977).

[c8] D. Amati and G. Veneziano, Phys. Lett. 83 B, 87 1979).

[c9] P. Mazzanti, R. Odorico and V. Roberto, Nucl. Phys. B 193, 541 (1981); Cho-Kuen Ng, Phys. Rev. D 31, 469 (1985).

[c10] Particle Data Group, Rev. Mod. Phys. 56, S1 (1984).

[c11] TASSO Collaboration, M. Althoff et al., Z. Phys. C 17, 5 (1983); TASSO Collaboration, R. Brandelik et al., Phys. Lett. 108 B, 71 (1982); , ibid. 94 B, 91 (1980); , ibid. 105 B, 75 (1981).

[c12] R. Cabenda, Ph.D. thesis, Cornell University, 1982.

[c13] R. D. Field, Phys. Lett. 135 B, 203 (1984).

[c14] H. Albrecht et al., Phys. Lett. 102 B, 291 (1981).

[c15] CLEO detects more charged pions than predicted, especially at large z. One might ask whether this indicates a problem with the theory, or an unsually high data set. We thus turn to comparison with other experiments, where the continuum two-jet cross section has been extensively studied. At 34 GeV, the agreement between TASSO and our Monte Carlo results is within 15% for, say, z >= 0.65. Hence there is no serious problem with the calculations at large z.

[c16] Using Webber's original set of parameters which contains a lower $Q_{0}$ value does not change this fact very much.

[c17] UA1 Collaboration, G. Arnison et al., Phys. Lett. 147 B, 493 (1984).

[c18] J. H. Kühn and S. Ono, Z. Phys. C 21, 395 (1984); ibid. 24, 404(E) (1984); J. H. Kühn and K. H. Streng, Nucl. Phys. B 198, 71 (1982); A. D. Martin, in New Particles 1985, proceedings of the Conference on New Particles, Madison, 1985, edited by V. Barger, D. Klein, and F. Halzen (World-Scientific, Singapore, in press).

[c19] S. Godfrey and N. Isgur, Phys. Rev. D 32, 189 (1985).

[c20] A. De Rújula, Howard Georgi and S. L. Glashow, Phys. Rev. D 12, 147 (1975).

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Monte Carlo simulation of jets in the upsilon and t-quarkonium regions

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