Quarks Leptons and the Big Bang

440 Pages·2001·3.62 MB·English

by  Jonathan Allday

Quarks, Leptons and
the Big Bang
Second Edition
Quarks, Leptons and
the Big Bang
Second Edition
Jonathan Allday
The King’s School, Canterbury
Institute of Physics Publishing
Bristol and Philadelphia
(cid:1)c IOPPublishingLtd2002
All rights reserved. No part of this publication may be reproduced,
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Agency under the terms of its agreementwith the Committee of Vice-
ChancellorsandPrincipals.
BritishLibraryCataloguing-in-PublicationData
AcataloguerecordforthisbookisavailablefromtheBritishLibrary.
ISBN0750308060
LibraryofCongressCataloging-in-PublicationDataareavailable
Firsteditionprinted1998
Firsteditionreprintedwithminorcorrections1999
CommissioningEditor:JamesRevill
ProductionEditor:SimonLaurenson
ProductionControl:SarahPlenty
CoverDesign:Fre´de´riqueSwist
MarketingExecutive:LauraSerratrice
Published by Institute of Physics Publishing, wholly owned by The
InstituteofPhysics,London
InstituteofPhysicsPublishing,DiracHouse,TempleBack,BristolBS1
6BE,UK
USOffice: InstituteofPhysicsPublishing,ThePublicLedgerBuilding,
Suite1035,150SouthIndependenceMallWest,Philadelphia,PA19106,
USA
TypesetinLATEX2ε byText2Text,Torquay,Devon
PrintedintheUKbyMPGBooksLtd,Bodmin,Cornwall
Contents
Prefacetothesecondedition ix
Prefacetothefirstedition xiii
Prelude:Settingthescene 1
1 Thestandardmodel 5
1.1 Thefundamentalparticlesofmatter 5
1.2 Thefourfundamentalforces 10
1.3 Thebigbang 14
1.4 Summaryofchapter1 18
2 Aspectsofthetheoryofrelativity 21
2.1 Momentum 21
2.2 Kineticenergy 28
2.3 Energy 31
2.4 Energyandmass 32
2.5 Reactionsanddecays 37
2.6 Summaryofchapter2 40
3 Quantumtheory 42
3.1 Thedoubleslotexperimentforelectrons 44
3.2 Whatdoesitallmean? 49
3.3 Feynman’spicture 50
3.4 Asecondexperiment 53
3.5 Howtocalculatewithamplitudes 56
3.6 Followingamplitudesalongpaths 59
3.7 Amplitudes,statesanduncertainties 72
3.8 Summaryofchapter3 82
vi Contents
4 Theleptons 85
4.1 Aspotter’sguidetotheleptons 85
4.2 Thephysicalpropertiesoftheleptons 87
4.3 Neutrinoreactionswithmatter 89
4.4 Somemorereactionsinvolvingneutrinos 93
4.5 ‘Whoorderedthat?’ 95
4.6 Solarneutrinosagain 98
4.7 Summaryofchapter4 99
5 Antimatter 101
5.1 Internalproperties 101
5.2 Positronsandmysteryneutrinos 107
5.3 Antiquarks 110
5.4 Thegeneralnatureofantimatter 112
5.5 Annihilationreactions 114
5.6 Summaryofchapter5 116
6 Hadrons 118
6.1 Thepropertiesofthequarks 118
6.2 Areviewofthestrongforce 122
6.3 Baryonsandmesons 123
6.4 Baryonfamilies 124
6.5 Mesonfamilies 129
6.6 Internalpropertiesofparticles 131
6.7 Summaryofchapter6 132
7 Hadronreactions 134
7.1 Basicideas 134
7.2 Basicprocesses 135
7.3 Usingconservationlaws 140
7.4 Thephysicsofhadronreactions 142
7.5 Summaryofchapter7 147
8 Particledecays 148
8.1 Theemissionoflightbyatoms 148
8.2 Baryondecay 149
8.3 Mesondecays 162
8.4 Strangeness 164
8.5 Leptondecays 165
8.6 Summaryofchapter8 166
9 Theevidenceforquarks 167
9.1 Thetheoreticalidea 167
Contents vii
9.2 Deepinelasticscattering 167
9.3 Jets 173
9.4 TheNovemberrevolution 178
9.5 Summaryofchapter9 179
10 Experimentaltechniques 181
10.1 Basicideas 181
10.2 Accelerators 182
10.3 Targets 188
10.4 Detectors 190
10.5 Acasestudy—DELPHI 197
10.6 Summaryofchapter10 201
Interlude1: CERN 203
11 Exchangeforces 210
11.1 Themodernapproachtoforces 210
11.2 Extendingtheidea 217
11.3 Quantumfieldtheories 222
11.4 Grandunification 234
11.5 Exotictheories 236
11.6 Finalthoughts 237
11.7 Summaryofchapter11 238
Interlude2: Antihydrogen 241
12 Thebigbang 244
12.1 Evidence 244
12.2 Explainingtheevidence 251
12.3 Summaryofchapter12 265
13 Thegeometryofspace 267
13.1 Generalrelativityandgravity 267
13.2 Geometry 269
13.3 Thegeometryoftheuniverse 272
13.4 Thenatureofgravity 276
13.5 Thefutureoftheuniverse? 279
13.6 Summary 281
14 Darkmatter 284
14.1 Thebaryonicmatterintheuniverse 284
14.2 Theevidencefordarkmatter 286
14.3 Whatisthedarkmatter? 298
14.4 Summaryofchapter14 315
viii Contents
Interlude3: Abriefhistoryofcosmology 319
15 Inflation—acureforallills 326
15.1 Problemswiththebigbangtheory 326
15.2 Inflation 334
15.3 Thereturnof(cid:2) 357
15.4 Thelastwordongalaxyformation 366
15.5 Quantumcosmology 368
15.6 Thelastword 370
15.7 Summaryofchapter15 370
Postlude: Philosophicalthoughts 374
Appendix1: NobelPrizesinphysics 378
Appendix2: Glossary 386
Appendix3: Particledatatables 403
Appendix4: Furtherreading 408
Index 413
Preface to the second edition
Itissurelyatruismthatifyouwroteabooktwice,youwouldnotdoit
thesamewaythesecondtime. Inmycase,Quarks,LeptonsandtheBig
Bangwashauledroundseveralpublishersundertheguiseofatextbook
for schools in England. All the time I knew that I really wanted it to
beapopularexpositionofparticlephysicsandthebigbang,butdidnot
thinkthatpublisherswouldtakeariskonsuchabookfromanunknown
author. Well, they were not too keen on taking a risk with a textbook
either. IntheendIdecidedtosendittoIOPPasalasttry. Fortunately
Jim Revill contacted me to say that he liked the book, but thought it
shouldbemoreofapopularexpositionthanatextbook...
Thisgoessomewaytoexplainingwhatsomehaveseenasslightlyodd
omissionsfromthematerialinthisbook—somementionofsuperstrings
asoneexample.Suchmaterialwasnotneededinschoolsandsodidnot
make it into the book. However, now that we are producing a second
editionthereis a chanceto correctthatandmake ita little morelike it
wasoriginallyintendedtobe.
I am very pleased to say that the first edition has been well received.
Reviewers have been kind, sales have been satisfying and there have
beenmanyemailsfrompeoplesayinghowmuchtheyenjoyedthebook.
Sixth formstudentshavewritten to say theylike it, a Universityof the
ThirdAge adoptedit as a coursebookand severalpeoplehave written
toaskmefurtherquestions(whichItriedtoanswerasbestIcould). It
has been fun to have my students come up to me from time to time to
saythattheyhavefoundoneofmybooksontheAmazonwebsiteand
(slightlysurprisedtoneofvoice)thereviewersseemtolikeit.
ix