Academia.eduAcademia.edu

Outline

Title
Abstract
Introduction
Data Analysis Overview
Analysis Technique and Results
Discussion of the Results
Fit Results
Analysis Using Second Order QCD Predictions
Analysis Using All-Orders Resummed Predictions
Summary of S Measurements
Data Analysis and Results
Model Independent Results
Data Analysis
Analysis of Two-Jet Events
Summary and Discussion
Data Selection
Summary
References
All Topics
Physics
Particle Physics

Studies of Quantum Chromodynamics with the ALEPH detector

Profile image of Alberto LusianiAlberto Lusiani

1998, Physics Reports

Abstract

Previously published and as yet unpublished QCD results obtained with the ALEPH detector at LEP1 are presented. The unprecedented statistics allows detailed studies of both perturbative and non-perturbative aspects of strong interactions to be carried out using hadronic Z and tau decays. The studies presented include precise determinations of the strong coupling constant, tests of its avour independence, tests of the SU(3) gauge structure of QCD, study of coherence eects, and measurements of single-particle inclusive distributions and two-particle correlations for many identied baryons and mesons.

References (254)

  1. 1 0:2 0.0045 0.0039 0:2 0:3 0.0143 0.0096 0:3 0:4 0.0185 0.0078 0:4 0:5 0.0251 0.0075 0:5 0:6 0.0256 0.0071 0:6 0:7 0.046 0.014 0:7 0:8 0.055 0.017 0:8 0:9 0.087 0.016 0:9 1:0 0.136 0.020 1:0 1:1 0.182 0.036 1:1 1:2 0.246 0.031 1:2 1:3 0.300 0.039 1:3 1:4 0.383 0.027 1:4 1:5 0.457 0.055 1:5 1:6 0.538 0.048 1:6 1:7 0.625 0.043 1:7 1:8 0.815 0.055 1:8 1:9 0.996 0.059 1:9 2:0 1.126 0.066 2:0 2:1 1.300 0.075 2:1 2:2 1.458 0.081 2:2 2:3 1.662 0.083 2:3 2:4 1.899 0.092 interval 1= tot d=d 2:4 2:5 2.12 0.10 2:5 2:6 2.27 0.11 2:6 2:7 2.55 0.13 2:7 2:8 2.73 0.12 2:8 2:9 3.06 0.13 2:9 3:0 3.19 0.14 3:0 3:1 3.49 0.14 3:1 3:2 3.79 0.16 3:2 3:3 3.91 0.16 3:3 3:4 4.20 0.17 3:4 3:5 4.49 0.19 3:5 3:6 4.47 0.19 3:6 3:7 4.88 0.21 3:7 3:8 5.11 0.21 3:8 3:9 5.41 0.23 3:9 4:0 5.50 0.24 4:0 4:1 5.53 0.25 4:1 4:2 5.92 0.29 4:2 4:3 6.06 0.30 4:3 4:4 6.43 0.36 4:4 4:5 6.34 0.34 4:5 4:6 6.07 0.40 4:6 4:7 6.83 0.60 4:7 4:8 8.3 3.5
  2. Table 30: Measured inclusive photon cross section. The errors include statistical and systematic References
  3. J. D. Bjorken and E. A. Paschos, Phys. Rev. 185 (1969) 1975.
  4. M. Y. Han and Y. Nambu, Phys. Rev. B139 (1965) 1006;
  5. E. Reya, Phys. Rep. 69 (1981) 195.
  6. H. Fritzsch, M. Gell-Mann and H. Leutwyler, Phys. Lett. B47 (1973) 365.
  7. D. J. Gross and F. Wilczek, Phys. Rev. Lett. 30 (1973) 1343.
  8. H. D. Politzer, Phys. Rev. Lett. 30 (1973) 1346.
  9. D. Buskulic et al., ALEPH collaboration, Phys. Lett. B303 (1993) 198.
  10. B. R. Webber, Phys. Lett. B339 (1994) 148;
  11. Yu. L. Dokshitzer and B. R. Webber, Phys. Lett. B352 (1995) 451;
  12. P. Nason and M. Seymour, Nucl. Phys. B454 (1995) 291;
  13. R. Akhoury and V. I. Zakharov, Phys. Lett. B357 (1995) 646; Nucl. Phys. B465 (1996) 295; M. Beneke and V. M. Braun, Nucl. Phys. B454 (1995) 253.
  14. M. Gell-Mann, Phys. Lett. 8 (1964) 214.
  15. G. Zweig, CERN-TH 401 and TH 412 (1964).
  16. E. D. Bloom et al., Phys. Rev. Lett. 23 (1969) 930;
  17. M. Breidenbach et al., Phys. Rev. Lett. 23 (1969) 935.
  18. R. P. F eynman, Photon Hadron Interactions, Benjamin, New York, 1972.
  19. P. M. Zerwas and H. A. Kastrup, eds., QCD 20 Years Later, W orld Scientic, Singapore (1993).
  20. G. Altarelli, Phys. Rep. 81 (1982) 1.
  21. D. H. Perkins, Introduction to High Energy Physics, Addison-Wesley, Menlo Park, California, 1987.
  22. J. Ellis, M. K. Gaillard, G. Ross Nucl. Phys. B111 (1976) 253.
  23. R. K. Ellis, D. A. Ross and A. E. Terrano, Nucl. Phys. B178 (1981) 421.
  24. A. Altarelli and G. Parisi, Nucl. Phys. B126 (1977) 298; Yu. L. Dokshitzer, Sov. Phys. JETP 46 (1977) 641.
  25. B. I. Ermolaev, V. S. Fadin, ZhETF Pis'ma 33 (1981) 285;
  26. A. H. Mueller, Phys. Lett. B104 (1981) 161;
  27. V. S. Fadin, Yad. Fiz. 36 (1982).
  28. D. Decamp et al., ALEPH Collaboration, Nucl. Instr. Methods A294 (1990) 121.
  29. D. Buskulic et al., ALEPH Collaboration, Nucl. Instr. Methods A360 (1995) 481.
  30. G. Batignani et al., 1991 IEEE Nuclear Science Symposium, Santa Fe, IEEE. Trans. Nucl. Sci. NS-39(4/5) (1992) Vol. 1, p. 438.
  31. G. J. Barber et al., Nucl. Instr. Methods A279 (1989) 212.
  32. W. B. Atwood et al., Nucl. Instr. Methods A306 (1991) 446.
  33. J. E. Campagne and R. Zitoun, Z. Phys. C43 (1989) 469.
  34. T. Sj ostrand, Comp. Phys. Comm. 82 (1994) 74.
  35. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C55 (1992) 209.
  36. W. Bartel et al., JADE Collaboration, Z. Phys. C33 (1986) 23;
  37. S. Bethke et al., JADE Collaboration, Phys. Lett. B213 (1988) 235.
  38. Proceedings of the Durham Workshop, W. J. Stirling, J. Phys. G: Nucl. Part. Phys. 17 (1991) 1567;
  39. N. Brown and W. J. Stirling, Phys. Lett. B252 (1990) 657;
  40. S. Bethke et al., Nucl. Phys. B370 (1992) 310.
  41. B. Andersson et al., Phys. Rep. 97 (1983) 31.
  42. L. L onnblad, Comp. Phys. Comm. 71 (1992) 15.
  43. G. Marchesini et al., Comp. Phys. Comm. 67 (1992) 465.
  44. C. Peterson et al., Phys. Rev. D27 (1983) 105.
  45. G. Gustafson, Phys. Lett. B175 (1986) 453;
  46. G. Gustafson, U. Pettersson, Nucl. Phys. B306 (1988) 746;
  47. B. Anderson et al., Z. Phys. C43 (1989) 621;
  48. B. Anderson, G. Gustafson, L. L onnblad, Nucl. Phys. B339 (1990) 393.
  49. P. Abreu et al., DELPHI Collaboration, Z. Phys. C65 (1995) 587.
  50. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C62 (1994) 1.
  51. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C62 (1994) 179.
  52. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B357 (1995) 699.
  53. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C69 (1996) 393.
  54. G. Hanson et al., Phys. Rev. Lett. 35 (1975) 1609.
  55. R. Brandelik et al., T ASSO Collaboration, Phys. Lett. B97 (1980) 453;
  56. Ch. Berger et al., PLUTO Collaboration, Phys. Lett. B97 (1980) 459.
  57. E. Laermann, K.H. Streng, P.M. Zerwas, Z. Phys. C3 (1980), 289; Erratum Z. Phys. C52 (1991) 352.
  58. M. A. Shifman, A. L. Vainshtein and V. I. Zakharov, Nucl. Phys. B147 (1979) 385.
  59. L. R. Surguladze and M. A. Samuel, Phys. Rev. Lett. 66 (1991) 560;
  60. S. G. Gorishny, A. L. Kataev and S. A. Larin, Phys. Lett. B259 (1991) 144.
  61. T. Hebbeker et al., Phys. Lett. B331 (1994) 165.
  62. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C62 (1994) 539.
  63. J. Alcaraz et al., The LEP Electroweak Working Group and the SLD Heavy Flavour Group, LEPEWWG/96-02.
  64. M. Martinez et al., Z. Phys. C49 (1991) 645.
  65. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B307 (1993) 209.
  66. E. Braaten, S. Narison and A. Pich, Nucl. Phys. B373 (1992) 581.
  67. F. Le Diberder and A. Pich, Phys. Lett. B286 (1992) 147; ibid. 289 (1992) 165.
  68. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C70 (1996) 561.
  69. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C70 (1996) 549.
  70. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C70 (1996) 579.
  71. L. Duot, in Proceedings of the QCD 94 Conference, ed. S. Narison, Nucl. Phys. (Proc. Suppl.) 39B (1995) 322.
  72. W. Bernreuther and W. Wetzel, Nucl. Phys. B197 (1982) 228.
  73. A. Pich, in Proceedings of the QCD 94 Conference, ed. S. Narison, Nucl. Phys. (Proc. Suppl.) 39B (1995) 326.
  74. P. Ball, M. Beneke and V. M. Braun, Nucl. Phys. B452 (1995) 563.
  75. G. Altarelli, P. Nason and G. Ridol, Z. Phys. C68 (1995) 257.
  76. Z. Kunszt et al., in Proceedings of the Workshop on Z Physics at LEP, eds. G. Altarelli, R. Kleiss and C. Verzegnassi, CERN Report 89-08, p. 373{453.
  77. T. Sj ostrand and M. Bengtsson, Comp. Phys. Comm. 43 (1987) 367.
  78. M. Bengtsson and T. Sj ostrand, Phys. Lett. B185 (1987) 435.
  79. G. Marchesini and B. Webber, Cavendish-HEP-88/7; Nucl. Phys. B310 (1988) 461; I. Knowles, Nucl. Phys. B310 (1988) 571.
  80. D. Decamp et al., ALEPH Collaboration, Phys. Lett. B255 (1991) 623.
  81. D. Decamp et al., ALEPH Collaboration, Phys. Lett. B257 (1991) 479.
  82. P. Nason, program EVENT, private communication.
  83. S. Catani et al., Nucl. Phys. B407 (1993) 3, and references therein.
  84. S. Catani et al., Phys. Lett. B263 (1991) 491.
  85. S. Catani, G. Turnock and B. R. Webber, Phys. Lett. B272 (1991) 368.
  86. S. Catani et al., Phys. Lett. B269 (1991) 432.
  87. G. Dissertori and M. Schmelling, Phys. Lett. B361 (1995) 167.
  88. D. Decamp et al., ALEPH Collaboration, Phys. Lett. B284 (1992) 163.
  89. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B357 (1995) 487; and Erratum, ibid. B364 (1995) 247.
  90. P. Nason and B. R. Webber, Nucl. Phys. B421 (1994) 473.
  91. G. Altarelli, R. K. Ellis, G. Martinelli and S.-Y. Pi, Nucl. Phys. B160 (1979) 301.
  92. V. N. Gribov and L. N. Lipatov, Sov. J. Nucl. Phys. 15 (1972) 78;
  93. G. Altarelli, G. Parisi, Nucl. Phys. B126 (1977) 298;
  94. Yu. L. Dokshitzer, Sov. Phys. JETP 46 (1977) 641.
  95. G. Gurci, W. Furmanski and R. Petronzio, Nucl. Phys. B175 (1980) 27;
  96. W. Furmanski and R. Petronzio, Phys. Lett. B97 (1980) 437.
  97. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B313 (1993) 535.
  98. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B313 (1993) 549.
  99. D. Decamp et al., ALEPH Collaboration, Phys. Lett. B273 (1991) 181.
  100. W. Braunschweig et al., T ASSO Collaboration, Z. Phys. C47 (1990) 187.
  101. A. Petersen et al., MARK II Collaboration, Phys. Rev. D37 (1988) 1.
  102. H. Aihara et al., TPC/2 Collaboration, Phys. Rev. Lett. 61 (1988) 1263; updated in G. D. Cowan, internal note TPC-LBL-94-01.
  103. O. Podobrin, CELLO Collaboration, Ph. D. thesis, Universit at Hamburg. See also ref. [85].
  104. Y. K. Li et al., AMY Collaboration, Phys. Rev. D41 (1990) 2675.
  105. P. Abreu et al., DELPHI Collaboration, Phys. Lett. B311 (1993) 408.
  106. See, for instance, Yu. L. Dokshitzer et al., Basics of Perturbative QCD, Editions Fron- ti eres, Gif-sur-Yvette (France) 1991, and references therein.
  107. C. P. F ong and B. R. Webber, Nucl. Phys. B355 (1991) 54.
  108. M. Schmelling, Status of the strong coupling constant, plenary talk at the XXVIII International Conference on High Energy Physics, Warsaw, July 1996. To appear in the Proceedings.
  109. R. M. Barnett et al., P article Data Group, Phys. Rev. D54 (1996) 1.
  110. S. Catani, G. Turnock and B. R. Webber, Phys. Lett. B295 (1992) 269.
  111. W. Braunschweig et al., T ASSO Collaboration, Z. Phys. C47 (1990) 181.
  112. B. Adeva et al., L3 Collaboration, Phys. Lett. B263 (1991) 551.
  113. P. Abreu et al., DELPHI Collaboration, Phys. Lett. B274 (1992) 498.
  114. M. H. Seymour, program EVENT2, private communication;
  115. S. Catani and M. H. Seymour, Phys. Lett. B378 (1996) 287.
  116. B. Lampe, Phys. Lett. B301 (1993) 435.
  117. R. D. Schamberger et al., CUSB Collaboration, Phys. Lett. B138 (1984) 225;
  118. S. E. Csorna et al., CLEO Collaboration, Phys. Rev. Lett. 56 (1986) 1221;
  119. H. Albrecht et al., A R GUS Collaboration, Phys. Lett. B199 (1987) 291;
  120. W. Kwong et al., Phys. Rev. D37 (1988) 3210;
  121. W. Braunschweig et al., T ASSO Collaboration, Z. Phys. C44 (1989) 365;
  122. A. Geiser, UA1 Collaboration, in Proceedings of the 27th Rencontre de Moriond: QCD and High Energy Hadronics Interactions, Les Arcs, France, ed. J. Tran Thanh Van (Editions Fronti eres) (1991) p. 159 .
  123. B. Adeva et al., L3 Collaboration, Phys. Lett. B271 (1991) 461;
  124. R. Akers et al., O P AL Collaboration, Z. Phys. C60 (1993) 397;
  125. P. Abreu et al., DELPHI Collaboration, Phys. Lett. B307 (1993) 221;
  126. R. Akers et al., O P AL Collaboration, Z. Phys. C65 (1995) 31;
  127. K. Abe et al., SLD Collaboration, Phys. Rev. D53 (1996) 2271.
  128. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B355 (1995) 381.
  129. T. Hebbeker, PITHA 91/08; Phys. Rep. 217 (1991) 69.
  130. J.G. K orner, G. Schierholz and J. Willrodt, Nucl. Phys. B185 (1981) 365;
  131. K.J.F. Gaemers and J.A.M. Vermaseren, Z. Phys. C7 (1980) 81;
  132. D. Danckaert et al., Phys. Lett. B114 (1982) 203.
  133. ALEPH Collaboration, D. Decamp et al., Phys. Lett. B284 (1992) 151.
  134. J.M. Scarr, I. ten Have, ALEPH-NOTE 89 -150.
  135. R. Tarrach, Nucl. Phys. B183 (1981) 384.
  136. F. Abe et al., CDF Collaboration, Phys. Rev. Lett. 74 (1995) 2626;
  137. S. Abachi et al., D0 Collaboration, Phys. Rev. Lett. 74 (1995) 2632.
  138. See, for instance, I. Antoniadis, J. Ellis, D.V. Nanopoulos, Phys. Lett. B262 (1991) 109.
  139. M. G. Alviggi et al., LEP Electroweak Working Group, LEPEWWG 95-01.
  140. Ya. I. Azimov et al., Z. Phys. C27 (1985) 65; Z. Phys. C31 (1986) 213.
  141. C. P. F ong and B. R. Webber, Phys. Lett. B229 (1989) 289.
  142. D. Buskulic et al., ALEPH Collaboration, CERN-PPE/96-43 (1996).
  143. M. Z. Akrawy et al., O P AL Collaboration, Phys. Lett. B247 (1990) 617.
  144. B. Adeva et al., L3 Collaboration, Phys. Lett. B259 (1991) 199.
  145. M. Chmeisanni, I.F.A.E., Universitat Autonoma de Barcelona, Annual Report (1992) 49.
  146. R. Odorico, University of Bologna report DFUB 92-6 (1992).
  147. M. Acciarri et al., L3 Collaboration, Phys. Lett. B353 (1995) 145.
  148. Yu. L. Dokshitzer et al., Phys. Lett. B245 (1990) 243.
  149. Yu. L. Dokshitzer, G. Marchesini, G. Oriani, Nucl. Phys. B387 (1990) 675.
  150. P. D. Acton et al., O P AL Collaboration, Z. Phys. C58 (1992) 207.
  151. W. Bartel et al., JADE Collaboration, Phys. Lett. B101 (1981) 129; Z. Phys. C21 (1983) 37.
  152. A. Aihara et al., TPC/2 Collaboration, Z. Phys. C28 (1985) 31;
  153. M. Altho et al., T ASSO Collaboration, Z. Phys. C29 (1985) 29;
  154. P. D. Sheldon et al., MARK II Collaboration, Phys. Rev. Lett. 57 (1986) 1398;
  155. P. Aarnio et al., DELPHI Collaboration, Phys. Lett. B240 (1990) 271;
  156. M. Z. Akrawy et al., O P AL Collaboration, Phys. Lett. B261 (1991) 334.
  157. Z. Koba, H. B. Nielsen, P. Olesen, Nucl. Phys. B40 (1972) 317.
  158. E. D. Malaza, B. R. Webber, Phys. Lett. B149 (1984) 501;
  159. E. D. Malaza, B. R. Webber, Nucl. Phys. B267 (1986) 702.
  160. S. Carius, G. Ingelmann, Phys. Lett. B252 (1990) 647;
  161. R. Szwed, G. Wrochna, Z. Phys. C47 (1990) 447;
  162. R. Szwed, G. Wrochna, A. K. Wr oblewski, Mod. Phys. Lett. A5 (1990) 981.
  163. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C69 (1995) 15
  164. V. Blobel, DESY 84-118 (1984).
  165. V. B. Anikeev and V. P. Zhigunov, Phys. Part. Nucl. 24 (4) (1993) 424.
  166. M. Schmelling, Nucl. Instr. Methods A340 (1994) 400.
  167. R. P. F eynman, Phys. Rev. Lett. 23 (1969) 1415.
  168. W. Braunschweig et al., T ASSO Collaboration, Z. Phys. C45 (1989) 193.
  169. D. Bender et al., HRS Collaboration, Phys. Rev. D31 (1985) 1.
  170. P. Abreu et al., DELPHI Collaboration, Z. Phys. C50 (1991) 185.
  171. W. Bartel et al., JADE Collaboration, Z. Phys. C20 (1983) 187.
  172. M. Schmelling, Physica Scripta 51 (1995) 683.
  173. R. Akers et al., O P AL Collaboration, Z. Phys. C61 (1994) 209.
  174. R. E. Ansorge et al., UA5 Collaboration, Z. Phys. C43 (1989) 357.
  175. P. Abreu et al., DELPHI Collaboration, Z. Phys. C52 (1991) 511.
  176. A. Giovannini and L. Van Hove, Z. Phys. C30 (1986) 391.
  177. Ya. B. Zel'dovich et al., Sov. Phys. Usp. 30 (1987) 353.
  178. A. Bialas and R. Peschanski, Nucl. Phys. B273 (1986) 703.
  179. D. Decamp et al., ALEPH Collaboration, Z. Phys. C53 (1992) 21.
  180. V. Raab, \Intermittenz bei 91 GeV in der Reaktion e + e ! Hadronen," Diplomarbeit an der Technischen Universit at M unchen (1991), MPI-PhE/92-06.
  181. W. Ochs and J. Wosiek, Phys. Lett. B68 (1993) 144;
  182. Yu. L. Dokshitzer and C. M. Dremin, Nucl. Phys. B402(1993)139;
  183. Ph. Brax, J. L. Meunier and R. Peschanski, Z. Phys. C62 (1994) 649;
  184. W. Ochs and J. Wosiek, Z. Phys. C68 (1995) 269.
  185. S. Catani et al., Nucl. Phys. B377 (1992) 445; Nucl. Phys. B383 (1992) 419;
  186. R. Akers et al., O P AL Collaboration, Z. Phys. C63 (1994) 363.
  187. O. Adriani et al., L3 Collaboration, Phys. Rep. 236 (1993) 207.
  188. B. Webber, private communication.
  189. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B346 (1995) 389.
  190. M. Z. Akrawy et al., O P AL Collaboration, Phys. Lett. B261 (1991)334;
  191. R. Akers et al., O P AL Collaboration, Z. Phys. C68 (1995) 179;
  192. P. Abreu et al., DELPHI Collaboration, Z. Phys. C70 (1996) 179;
  193. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B346 (1995) 389.
  194. M. Derrick et al., HRS Collaboration, Phys. Lett. B165 (1985) 449;
  195. P. Abreu et al., DELPHI Collaboration, Z. Phys. C56 (1992) 63.
  196. D. Buskulic et al., ALEPH Collaboration, Nucl. Instr. Methods A346 (1994) 461;
  197. D. Decamp et al., ALEPH Collaboration, Phys. Lett. B266 (1991) 218.
  198. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B352 (1995) 479.
  199. D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B384 (1996) 353.
  200. R. Akers et al., O P AL Collaboration, Phys. Lett. B352 (1995) 176.
  201. G. Alexander et al., O P AL Collaboration, Z. Phys. C69 (1996) 543.
  202. P. D. Acton et al., O P AL Collaboration, Z. Phys. C58 (1993) 405;
  203. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C57 (1993) 17;
  204. P. Abreu et al., DELPHI Collaboration, Z. Phys. C53 (1992) 555;
  205. O. Adriani et al., L3 Collaboration, Phys. Lett. B292 (1992) 472.
  206. E. W. N. Glover and W. J. Stirling, Phys. Lett. B295 (1992) 128.
  207. G. Kramer and H. Spiesberger, \Matrix element calculation of quark bremsstrahlung in O( S )", DESY 92-022 (1992), contribution to the Workshop on Photon Radiation from Quarks, Annecy, F rance, 1991.
  208. E. W. N. Glover and A. G. Morgan, Z. Phys. C62 (1994) 311.
  209. The LEP Collaborations and the LEP Electroweak Working Group, CERN-PPE/93-157.
  210. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C69 (1996) 365.
  211. D. Decamp et al., ALEPH Collaboration, Z. Phys. C66 (1995) 355.
  212. R. Akers et al., O P AL Collaboration, Z. Phys. C63 (1994) 181.
  213. R. Itoh et al., Phys. Rev. Lett. 345 (1995) 335.
  214. M. Altho et al., T ASSO Collaboration, Z. Phys. C17 (1983) 5.
  215. W. Braunschweig et al., T ASSO Collaboration, Z. Phys. C42 (1989) 189.
  216. H. Aihara et al., TPC Collaboration, Phys. Rev. Lett. 61 (1988) 1263.
  217. G. D. Cowan, University of California, LBL-24715 (1988).
  218. R. Barate et al., ALEPH Collaboration, CERN-PPE/96-168.
  219. D. Decamp et al., ALEPH Collaboration, Phys. Lett. B292 (1992) 210.
  220. D. Buskulic et al., ALEPH Collaboration, Z. Phys. C69 (1996) 379.
  221. D. Decamp et al., ALEPH Collaboration, Z. Phys. C64 (1994) 361.
  222. P. D. Acton et al., O P AL Collaboration, Phys. Lett. B291 (1993) 503.
  223. M. Baubillier et al., Z. Phys. C23 (1984) 213.
  224. B. Anderson et al., Lund Report LU TP 84-9 (1984).
  225. H. Aihara et al., TPC/2 Collaboration, Phys. Rev. Lett. 55 (1985) 1047.
  226. H. Albrecht et al., A R GUS Collaboration, Z. Phys. C43 (1989) 45.
  227. B. R. Webber, private communication.
  228. D. Decamp et al., ALEPH Collaboration, Z. Phys. C54 (1992) 75.
  229. M. G. Bowler, Z. Phys. C29 (1985) 617.
  230. G. I. Kopylov, M. I. Podgoretski i, Sov. J. Nucl. Phys. 18 (1974) 336 and Sov. J. Nucl. Phys. 19 (1974) 215.
  231. R. Lednicky, V. L. Lyuboshits, Sov. J. Nucl. Phys. 35 (1982) 770.
  232. M. G. Bowler, OUNP-91-23 (1991).
  233. H. Aihara et al., TPC-PEP4 Collaboration, Phys. Rev. D31 (1985) 996.
  234. P. A v ery et al., CLEO Collaboration, Phys. Rev. D32 (1985) 2294.
  235. M. Altho et al., T ASSO Collaboration, Z. Phys. C30 (1986) 355.
  236. I. Juri ci c et al., Mark II Collaboration, Phys. Rev. D39 (1989) 1.
  237. P. D. Acton et al., O P AL Collaboration, Phys. Lett. B298 (1993) 456.
  238. P. Abreu et al., DELPHI Collaboration, Z. Phys. C63 (1994) 17.
  239. D. R. T. Jones, Nucl. Phys. B74 (1974) 531;
  240. D. Caswell, Phys. Rev. Lett. 33 (1974) 244.
  241. O. Tarasov, A. Vladimirow and A. Zharkov, Phys. Lett. B93 (1980) 429.
  242. O. Nachtmann and W. Wetzel, Nucl. Phys. B187 (1981) 333.
  243. W. Bernreuther and W. Wetzel, Nucl. Phys. B197 (1982) 228;
  244. W. Bernreuther, Annals of Physics 151 (1983) 127;
  245. W. J. Marciano, Phys. Rev. D29 (1984) 580;
  246. G. Rodrigo and A. Santamaria, CERN-TH.6899/93.
  247. G. Montagna et al., Nucl. Phys. B401 (1993) 3, Comp. Phys. Comm. 76 (1993) 328.
  248. A. Djouadi, J. H. K uhn and P. M. Zerwas, Z. Phys. C46 (1990) 411.
  249. B. A. Kniehl and J. H. K uhn, Phys. Lett. B224 (1989) 229;
  250. B. A. Kniehl and J. H. K uhn, Nucl. Phys. B329 (1990) 547.
  251. K. G. Chetyrkin and O. V. Tarasov, Phys. Lett. B327 (1994) 114.
  252. K. G. Chetyrkin and J. H. K uhn, Phys. Lett. B248 (1990) 359;
  253. K. G. Chetyrkin, J. H. K uhn and A. Kwiatkowski, Phys. Lett. B282 (1992) 221.
  254. S. C. Generalis, J. Phys. G15 (1989) L225.

Related papers

Heavy flavour production and decay with prompt leptons in the ALEPH detector
Alberto Lusiani

1994

In 431 000 hadronicZ decays recorded with the ALEPH detector at LEP, the yields of electrons and muons in events with one or more prompt leptons have been analysed to give information on the production and decay of heavy quarks. The fractions of and events are measured to be 0.219±0.006±0.005 and 0.165±0.005±0.020, and the corresponding forward-backward asymmetries at theZ mass are measured to be 0.090±0.013±0.003 and 0.111±0.021±0.018, after QED and QCD corrections.

View PDFchevron_right
Measurements of the Strong Coupling Constant and the QCD Colour Factors using Four-jet Observables from Hadronic Z Decays
Victoria Girón

2003

Data from e + e − annihilation into hadrons, taken with the ALEPH detector at the Z resonance, are analyzed. The four-jet rate is studied as a function of the resolution parameter and compared to next-toleading order calculations combined with resummation of large logarithms. Angular correlations in four-jet events are measured and compared to next-to-leading order QCD predictions. With these observables two different measurements are performed. In a first analysis the strong coupling constant is measured from the four-jet rate yielding αs(MZ) = 0.1170 ± 0.0001(stat) ± 0.0013(sys) .

View PDFchevron_right
Heavy quark tagging with leptons in the ALEPH detector
J. Sedgbeer

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1994

Semileptonic decays of heavy quarks yield prompt leptons which can be used to identify events resulting from the decays of the Z into cc and bb pairs. The procedures adopted to obtain clean samples of inclusive leptons with the ALEPH detector are described . Electron identification makes use of ionization measurements in the tracking system of ALEPH and the shape of showers in the electromagnetic calorimeter . Muons are identified using the tracking capabilities of the hadron calorimeter, together with the muon chamber information. Distinguishing the sources of prompt lepton production requires the determination of the lepton's transverse momentum with respect to the parent hadron's flight direction. As the latter is not directly measurable, the results of an algorithm are presented which uses the information produced by the ALEPH detector to achieve the most effective axis from which the transverse momentum should be measured .

View PDFchevron_right
A simultaneous measurement of the QCD colour factors and the strong coupling
Viktor Zacek

The European Physical Journal C, 2001

Using data from e + e − annihilation into hadrons, taken with the OPAL detector at LEP at the Z pole between 1991 and 1995, we performed a simultaneous measurement of the colour factors of the underlying gauge group of the strong interaction, C F and C A , and the strong coupling, α s. The measurement was carried out by fitting next-to-leading order perturbative predictions to measured angular correlations of 4-jet events together with multi-jet related variables. Our results, C A = 3.02 ± 0.25(stat.) ± 0.49(syst.) , C F = 1.34 ± 0.13(stat.) ± 0.22(syst.) , α s (M Z) = 0.120 ± 0.011(stat.) ± 0.020(syst.) , provide a test of perturbative QCD in which the only assumptions are non-abelian gauge symmetry and standard hadronization models. The measurements are in agreement with SU(3) expectations for C F and C A and the world average of α s (M Z).

View PDFchevron_right

Related topics

  • Particle Physics
  • Quantum Chromodynamics
    • 580 California St., Suite 400
    San Francisco, CA, 94104
    © 2025 Academia. All rights reserved