Physics for a New Generation: Prospects for High-Energy Physics at New Accelerators Proceedings of the XXVIII Int. Universitätswochen für Kernphysik, Schladming, Austria, March 1989

314 Pages·1990·17.65 MB·English

by  A. Bartl

Physics for a New Generation
H. Latal H. Mitter (Eds.)
Physics
for a New Generation
Prospects for High-Energy Physics
at New Accelerators
Proceedings of the
XXVIII Int. Universitatswochen fOr Kernphysik
Schladming, Austria, March 1989
With 226 Figures
Springer-Verlag Berlin Heidelberg New York
London Paris Tokyo Hong Kong Barcelona
Professor Dr. Heimo Latal
Professor Dr. Heinrich Mitter
Institut fOr Theoretische Physik, Karl-Franzens-Universitat, Universitatsplatz 5,
A-8010 Graz, Austria
ISBN-13: 978-3-642-75569-9 e-ISBN-13:978-3-642-75567-5
001: 10.1007/978-3-642-75567-5
Library of Congress Cataloging-in-Publication Data. Internationale Universitatswochen fOr Kernphysik der
Karl-Franzens-Universitat Graz (28th: 1989 : Schladming, Austria) Physics for a new generation: prospects
for high-energy physics at new accelerators: proceedings olthe XXVllllnt. Universitatswochen fOr Kernphy
sik, Schladming, Austria, March 1989/ H. Latal, H. Mitter, eds. p. cm. Includes bibliographical references.
ISBN-13: 978-3-642-75569-9 1. Particles (Nuclear physics) - Congresses. 2. Quantum chromodynamics -
Congresses. I. Latal, H. (Heimo). 1939-II. Mitter, Heinrich. III. Title. QC793.157 1989 539.7'2 - dc20
90-9665
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Preface
This volume contains the written versions of invited lectures presented at the 28th
"Internationale Universitatswochen fUr Kernphysik" in Schladming, Austria in March
1989.
The generous support of our sponsors, the Austrian Ministry of Science and
Research, the Government of Styria, and others, made it again possible to invite
expert lecturers. The courses were centered on elementary particle physics to be
performed with large accelerators accessible in the immediate future, including some
reports on the current situation. Thanks to the efforts of the speakers it was possible
to obtain excellent surveys.
After the School the lecture notes were revised and partially rewritten in TPC by
the authors, whom we thank for their labour. Unfortunately the report on the situation
at SLAC by M. Swartz could not be included.
Thanks are also due to the publishers for their patience.
Graz, Austria H. Latal
December 1989 H. Mitter
v
Contents
Phenomenology of and Beyond the Standard Electroweak Model
By A. Bartl, H. Pietschmann, and H. Stremnitzer (With 6 Figures) 1
1. The Standard Model (H. Pietschmann) . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Introduction ........................................... 1
1.2 Defining the Standard Model ............................. 1
1.3 Testing the Standard Model ............................... 4
1.4 Predictions ............................................ 5
1.5 Open Questions ........................................ 6
1.6 Hypotheses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.7 Conclusion ............................................ 9
2. Beyond the Standard Model: Supersymmetry (A. Bartl) . . . . . . . . . . . . 9
2.1 Supersymmetric Extension of the Standard Model ............ 10
2.2 Production and Decay of Supersymmetric Particles ..... . . . . . . 17
3. Beyond the Standard Model: Composite Models (H. Stremnitzer) 28
3.1 Introduction ........................................... 28
3.2 The Size of Composite Quarks ............................ 29
3.3 Quantum Preon Dynamics ................................ 30
3.4 Other Features of Composite Models ....................... 33
References ..................................................... 34
Physics at LEP
By H. Schopper (With 82 Figures) ................................. 39
1. Introduction ......... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2. LEP Machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.1 LEP Parameters ........................................ 40
2.2 Injection System ........................................ 43
2.3 Luminosity. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 44
2.4 Status of LEP. Tests and Plans for the Commissioning ........ 46
2.5 Up-grading of LEP ..................................... 47
3. LEP Detectors .............................................. 49
4. Physics of the ZO • . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . 55
4.1 z!1 Parameters in the Standard Model ....................... 56
4.1.1 Branching Ratios. Total Width ...................... 57
4.1.2 ZO Line Shape ................................... 58
4.2 Radiative Corrections to the ZO Mass and Width ............. 60
4.2.1 QED Corrections ................................. 61
VII
4.2.2 Weak Corrections ................................ 62
4.2.2.1 The On-Mass-Shell Definition of sin2 fJw ...... 63
4.2.2.2 Introduction of an Effective Weak Angle ...... 66
4.2.3 Hadronic Decays and QCD Corrections ............... 67
4.2.4 Summary of the Radiative Corrections ............... 67
4.3 Strategy to Determine the Z-Parameters from the Line Shape ... 68
4.4 Asymmetries at the z!! Peak .............................. 70
4.4.1 Definition of Asymmetries ......................... 70
4.4.2 AFB and ALR for Leptons in the Final State ........... 75
4.4.3 Asymmetries for Heavy Quarks ..................... 78
4.4.4 Polarization Asymmetry for Tau Decays .............. 79
4.5 Neutrino Counting ...................................... 83
4.5.1 Neutrino Counting from the Z-Width ................. 83
4.5.2 Radiative Neutrino Counting ....................... 84
5. QCD Tests ................................................. 86
5.1 Cross Section, Thrust, Oblateness and Sphericity ............. 87
5.2 Fragmentation Models ................................... 88
5.3 Test of the Non-Abelian Character of QCD .................. 90
6. Search for Supersymmetric Particles .. . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.1 General Remarks ....................................... 97
6.2 Experimental Searches for Supersymmetric Particles .......... 98
6.2.1 Wino Pair Production ............................. 99
6.2.2 Associated Zino-Photino Production ................. 100
6.2.3 Three-Body Final States ........................... 103
6.3 Conclusions ........................................... 106
7. Search for Higgs Particles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.1 General Properties of the Higgs ........................... 108
7.1.1 The Standard Model Higgs ......................... 109
7.1.1.1 Higgs Decay into Fermions ................. 109
7.1.1.2 Higgs Decay into Bosons ................... 11 0
7.1.2 The Su persymmetric Higgses ....................... 11 0
7.2 Higgs Search at the ZO Peak (LEP 100) ..................... 112
7.2.1 Search for the Standard Model Higgs ................ 112
7.2.2 Search for the SUSY Higgs ........................ 117
7.3 Higgs Search at LEP 200 ................................ 119
7.3.1 Higgs Search Below the WW Threshold (at 160 GeV) .. 120
7.3.2 Higgs Search Above the WW Threshold (at 200 GeV) .. 123
7.4 Higgs from Toponium Decay ............................. 124
7.5 Search for Charged Higgses .............................. 126
7.6 Light Higgses .......................................... 130
8. Miscellaneous Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
8.1 Top Search ............................................ 134
8.2 B-Physics at LEP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.3 Other New Particles ..................................... 138
References ..................................................... 139
VIII
The HERA Project
By R. FeIst (With 51 Figures) .................................... . 141
1. Introduction ............................................... . 141
2. The Machine .............................................. . 141
2.1 Superconducting Magnets ............................... . 143
2.2 Interaction Region and Spin Rotator ....................... . 145
3. HERA Physics ............................................ . 147
3.1 Deep Ineleastic Scattering ............................... . 148
3.1.1 The Standard Prejudice ........................... . 148
3.1.2 Tests of the Standard Model at HERA ............... . 157
3.1.3 Speculations .................................... . 155
3.2 Particle Production ..................................... . 161
3.2.1 New Particles ................................... . 161
3.2.2 Heavy Quark Production .......................... . 166
3.3 W-Production ......................................... . 169
4. Detection Facilities ......................................... . 170
4.1 General Requirements .................................. . 170
4.2 The HI-Detector ...................................... . 174
4.3 The ZEUS Detector .................................... . 176
5. Status 178
Acknowledgement ............................................. . 179
References ................................................... . 179
Physics in pp Collisions
By F. Pauss (With 27 Figures) ................................... . 181
1. Introduction ............................................... . 181
2. Production and Decay of IYBs ............................... . 183
2.1 IYB Masses and Standard Model Parameters ............... . 183
2.2 IYB Production Cross-Sections and e-j.L-T Universality ....... . 185
2.3 IYB Transverse-Momentum Distribution ................... . 187
2.4 Measurement of as Usi~g W + Jet Data ................... . 188
2.5 Number of Light Neutrino Species ........................ . 189
2.6 Outlook .............................................. . 191
3. Heavy-Flavour Production ................................... . 192
3.1 Inclusive b-Quark Production ............................ . 192
3.2 BO_Bo Oscillations ..................................... . 195
4. Search for Heavy Quarks (t, b') ............................... . 196
4.1 Outlook .............................................. . 198
5. Searches for New Physics ................................... . 201
5.1 Search for Heavy Leptons and the Number of Neutrino Species . 201
5.2 Searches for Supersymmetric Particles ..................... . 202
5.3 Searches for Additional Vector Bosons .................... . 204
5.4 Axigluon Search ....................................... . 205
5.5 Quark Substructure .................................... . 206
5.6 Outlook .............................................. . 208
IX
6. Conclusions .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
References ...................................................... 213
Weak Mixing, CP Violation and the Standard Model
By K. Kleinknecht (With 27 Figures) ............................... 217
1. Weak Mixing of Quarks .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
1.1 Kobayashi-Maskawa Matrix .............................. 218
1.2 Experimental Constraints on the KM Matrix ................. 219
1.2.1 Light Quark Couplings ............................ 219
1.2.2 Charm-Quark Couplings ........................... 219
1.2.3 Bottom-Quark Couplings ....... : ............. ;. . . . . 221
1.3 Allowed Ranges of Mixing Angles for 3 or 4 Generations . '. . . . . 223
2. CP Violation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
2.1 Phenomenology and Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
2.2 New Experiments on c;' / c; •••••••••••••••••••••••••••••••• 229
3. Implications of Experimental Results on the Standard Model Parameters 237
4. Beyond the Standard Model: Searches for Rare Kaon Decays . . . . . . . 241
5. Conclusions - Outlook ....................................... 246
References ..................................................... 247
Recent Developments in Perturbative QCD
By Z. Kunszt (With 33 Figures) ................................... 251
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
2. General Properties of Perturbative QCD . . . . . . . . . . . . . . . . . . . . . . . . . 252
2.1 On the Validity of the Perturbative Description ............... 252
2.2 Theorems of Perturbative QCD ............................ 253
2.3 Renormalization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
2.3.1 Lagrangian ...................................... 255
2.3.2 Renormalization Factors ........................... 256
2.3.3 Comment on the Axial Gauge ...................... 257
2.3.4 The Running Coupling Constant ............ . . . . . . . . 257
2.3.5 The Renormalization Group Equations . . . . . . . . . . . . . . . 258
2.4 The Total Cross Section of e+e- Annihilation into Hadrons .... 259
a! ..................
2.4.1 Perturbative Expansion to Order 259
2.4.2 Measurement of R at the Z-Pole .................... 261
3. Deep Inelastic Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
3.1 Structure Functions and Cross Sections ..................... 261
3.2 Phenomenology of the Parton Density Functions ... . . . . . . . . . . 266
3.3 Spin-Dependent Structure Functions ........................ 268
3.3.1 The Puzzling EMC Data ........................... 268
3.3.2 Large Lls Versus Large LlG ........................ 270
3.3.3 The Contribution of the Axial Anomaly .............. 271
3.3.4 Parametrization and Measurement of the Spin-Dependent
Gluon Density ................................... 273
x
4. Large Transverse Momentum Reactions in Hadron-Hadron Collisions 278
4.1 ,*-, W- and Z-Production ................................ 278
4.1.1 Factorization Theorem for the Drell-Yan Process ....... 278
4.1.2 Total Cross Sections and p ..L -Distribution ............. 280
4.1.3 Gauge Boson Production in Association with Multi-jets 281
4.2 Heavy Quark Production ................................. 281
4.2.1 On the Validity of the Factorization Theorem .......... 281
4.2.2 Cross Section Formulae ........................... 282
4.2.3 Phenomenology of Heavy Quark Production ........... 283
5. Jet Production at Next-to-Leading Order ......................... 284
5.1 Jet Production in e+e- Annihilation ........................ 284
5.1.1 QCD and the Monte Carlo Approach ................. 286
5.1.2 Thrust Distributions ............................... 287
5.1.3 Jet Cluster Distributions ........................... 291
5.1.4 Inclusive Jet Production ........................... 293
5.2 Jet Production in Hadron-Hadron Collisions ................. 295
5.2.1 Partonic Versus Hadronic Jet Cross Sections ........... 296
5.2.2 The Cross Section of Inclusive Jet Production ......... 297
References ..................................................... 303
XI
Phenomenology of
and Beyond the Standard Electroweak Model
A. Bartl, H. Pietschmann, and H. Stremnitzer
Institut fiir Theoretische Physik, Universitlit Wien
Boltzmanngasse 5, A-1090 Wien
1. The Standard Model
1.1 Introduction
It has become a ritual to begin any lecture on the Standard Model for electroweak
interactions (which might better be called Quantum Flavourdynamics, QFD) with
a lament about its weaknesses; i.e. there are so many free parameters, there is no
genuine unification and so on. In these lectures, we shall not follow this ritual. Rather,
we shall try to emphasize the tremendous achievements without forgetting that they
lead naturally to new open problems and the question of what comes beyond. In this
spirit, a recent reference volume by D. Haidt and one of the authors on electroweak
interactions [1.1] has been concluded with the following statement:
At the end of this volume it is fair to conclude that the vast body of experimental
weak and electromagnetic data, in some cases accurate to the level of 10-10, appears
systematically ordered and quantitatively described within Quantum Flavourdynam
ics. This is one of the rare moments in the history of physics, where a theory is
complete up to a certain level and when confronted with experiments does not re
veaL essentiaL refutations. It is on the basis of this success that the questions Leading
beyond the present framework gain their relevance.
1.2 Defining the Standard Model
Since the notion of the "Standard Model" is not always used in precisely the same
way, let us give a definition for the sake of these lectures. We shall do it by stating six
basic assumptions, see Table 1.1. Any extension or deviation from these assumptions
shall be denoted explicitly, for instance as "modified standard model" or the like.
Table 1.1 represents the strongest set of assumptions (i.e. the most minimal
model) consistent with all experiments as of today. Slight modifications can easily
be made, for example assumption e) can be dropped if a neutrino mass is empirically
demonstrated beyond doubt.
On the basis of these assumptions, a Lagrangian for the standard model (or QFD)
can be written down. The Higgs-mechanism is to be applied for generating masses.
Physics for a New Generation Editors: H. Lata!· H. Mitter
© Springer-Verlag Berlin, Heidelberg 1990