Part III Particle Physics
Major Option
Michaelmas 2022
Part III Particle Physics Lecture Handouts
One slide per page: pdf
Two slides per page: pdf
Replacement for slides 23-36: pdf
Supplement
on particle exchange and the existence of propagators: pdf
Supplement
on electroweak unification: pdf
Supplement on
SU(2) vs SU(3) comparison, and general SU(3) multiplet:
pdf
(see also the Particle Data Group's summary of SU(n) multiplet properties)
Examples sheet
Clarifications to printed version of 2022 handout:
- It would be nice if slide 66 or 67 showed that the sigma dot p matrix is equal to E squared minus m squared (times the identity matrix). If this were shown, then it would be easier to argue that the two equations in D12 are identical, and so it suffices to satisfy either one. That argument would be nicer than the (correct) one presented.
- The last "and" on slide 75 should say "and so".
- It might be nice to add a statement of Ehrenfest's Theorem to the slides computing Dirac's [H,L] and [H,S].
- It is confusing that quantities like M_(cx;a) and M_(c;ay) on my propagators.pdf are called g_a in the rest of the handout, and similarly that M_(d;bx) and M_(dy;b) are called g_b elsewhere.
- Also on the propagators.pdf handout, there is a typo in one of the places where factors of Sqrt(2 E) are being pulled out to write an M(abcd) in terms of a T(abcd). Whereas the factors which should come out ought to be a power of (2Ea)(2Eb)(2Ec)(2Ed) they are accidentally written as a power of (2Ea)(2Eb)(2Ec)(2Eb).
- Slide 176: it would be more correct to replace the words of the second bullet point with the words: "Note that the Rosenbluth formula would reverts to the formula for scattering off a point like particle (e.g. page 172 or 173) only when GE(q)=GM(q)=1. Therefore a point like fermionic proton would have these unit values of GE and GM, at least for small qSquared.
- Slide 176: Arguably the second last bullet point on this slide would be better written by removing references to what we might `expect' for the proton, and changing them to statements that `we will measure what GE and GM are for the proton, and if we find values different to 1 then we will see evidence for it being a non-pointlike fermion.
- On slide 187, the words "So y is the fractional energy loss of the incoming particle" might benefit from having "in the fixed target (lab) frame" tacked onto their end.
- Technically the argument at the top of slide 216 is not sufficient to require U to be unitary. It would need to have the bra-psi and the ket-psi to be from different states, and then it would be rigorous.
- Slide 312: "k=1,3" should say "k=1,2,3"
- There is a reference on slide 314 to "Handout 2 Appendix V". However, in Handout 2 the labels for Appendices IV and V seem to have disappeared. The material in Handout 2 that should be labelled Appendix V begins on slide 109. The reference on slide 314 should therefore be changed to point at slide 109.
- The RHS of the expression for the "QED vertex" in the middle of slide 318 has four terms on the RHS, two of which are known to be zero from proofs in earlier parts of the course. A mini-reminder proof of why one of them is zero is shown in the bottom half of slide 318. It is a shame, therefore, that the slide does not simply list the QED vertex in its simpler LL+RR form rather than leaving it in the LL+RR+LR+RL term shown. In future, it would be clearer to give the mini-proof first, and then list the QED vertex second, with the two zero-parts shown crossed out. Or something like that.
- Maybe it would be better if the argument of slide 382 were deleted and replaced with just a listing of the remaining four of the six allowed transition rates of which the first two were shown on slide 381. Then one could simply compare the rate for (nue to numu) to the rate for (nuebar to numubar) without having to rely on assumptions of CPT symmetry.
- It might help to move the PMNS matrix slide (slide 386) to just after slide 373.
- Slide 416 should have the left-hand histogram labelled "electron" events, while the right-hand histogram should be labelled "muon" events. (Also, aside: if one wanted to one could update them with the most recent versions of these plots in Fig 14.4 of the PDG's review of neutrino mixing.)
- 23rd Nov 2022: as the person running the course, I formally remove slides 453 and 454 from this year's version of the course, and replace them with just the statement that "for reasons equivalent to those advanced on slides 381-382 in connection with the PMNS matrix, the imaginary parts of the CKM matrix can drive CP violation".
- Note to my future self: I should consider deleting slides 478-483 from the course as they add little to the whole. Though if I do that i have to be careful not to break Q26 or Q27 referred to on slides 496 or 497.
- Arguably the I3 in the blue-boxed expression for CA on slide 494 should have a subsript L (or similar) to emphasise that it's referring to the non-trivial I3W of the left-handed state of the particle in question, not the trivial zero IO3W of the right-handed state.
- It does feel like the whole EW part should be replaced by an extension of the electroweak_supplement pdf document linked off the top of this web page.
- I could perhaps also take out 512 in future (Bhabha scattering).
- I have not yet independently verified this, but a student reports a factor 2 missing in a j near/after slide 53 on currents for KG or Dirac or ShrEq. I presume he sees j=|N|^2 p and expects j=2|N|^2 p. This should be checked.
Demonstrating/Supervision arrangements for 2022
Choose an examples class slot for the term through the doodle doodle poll here. [Not live until midday Weds 12th October 2022.] Schedules for individual supervisors may be subject to change, but there should be four supervisions throughout the term, with the first class being during the week beginning 24th Oct. Please be sure to only select one option in the doodle poll, so as not to double book. Individual supervisors will be in contact with further information on the questions that will be covered in each class, and the location of the classes. Questions about examples classes should be addresssed via email to supervisors jbex and longt565 at hep.phy.cam.ac.uk in the first instance.
Past tripos papers (including worked solutions)
See this separate page.
Books
There is one book with a notable connection to this course: "Modern Particle Physics" by Prof Mark Thomson of The Cavendish. I draw your attention to this book as Prof Thomson lectured this very course in 2008, 2009, 2010 and 2011 (before I took over in 2012). He revised the course substantially over that time, and the course you see now is substantially the same as it was when he left it. His book was his attempt to turn the course into a publication, and as such, there ought not to be a book more closely related to this course than it.
Ephemera
- Anglepoise chairs in USA15, LHC Point 1, CERN
- Rodgers MRI PhD.
- Cernettes performing "Collider", and the first ever photo on the web.
- New (2021) Yukawa Higgs Mechanism Simulator.
- Old (2015) WavesOnStringsLagrangian relating to this Higgs mechanism simulator which is launchable here.
- Search for Non-Standard Sources of Parity Violation in Jets at s√=8 TeV with CMS Open Data.
- Second most important result ever to come out of CERN.
- My LHCb 2015+2019 pentaquarks summary.
- LHCb 2019 pentaquarks paper.
- LHCb 2015 pentaquarks paper.
- 2016 PDG entry for Top Quark mass. (Or browse via: PDG, particle listigs, quarks, quarks , t quark)
- Christchurch Earthquake, 2016, New Zealand, as seen by the LHC.
- Never Lubricate the Davy.
- Prof Dirac's gown.
- BS - BSbar mixing.
- Revision notes on multiplets from a past student of the course (Zain_Ibrahim_Siddiqi, zis24) uploaded with permission.
- ATLAS Higgs Discovery paper:
- Constraints on Heffalon production at the LHC.
- Heffalon resources elsewhere on the web.
- Dirac discovers another attractive force.
- The moodle link for the course is here but it is not currently used for anything.
- A failed attempt to win Oriel College's "Eugene Lee-Hamilton Prize". The Provost and Fellows of Oriel College offer a prize of £60 for the best Petrarchan Sonnet in English submitted by an undergraduate of Oxford or Cambridge, on a subject to be chosen by the candidate. Enjambment between the eighth and ninth lines will be permitted. Some past entries from students on this course:
- “In the world of the very small”, by Sam Reynolds
- “Ode to the Cavendish”, by Aaron Smith and Elle Wyatt (first entry from Part IVs!)
- “Most cows don't have Facebook”, by Aaron Smith, Hannah Horton, and Elle Wyatt,
- “One Strange Day”, by Richard Williams
- “Understanding Particle Physics”, by Olivia Morley
- “Solo et pensoso, quantizzava campi”, by Stefano De-Nicloa
- [Currently untitled], by Raza Habib
- “Anthropic Principles”, by Will Benfold
- “Susy's Swansong”, by Matthew Lim
- “Bonnet Sonnet”, by Jay Man (actually this isn't the sonnet, which is secret, it's the instruction not to publish the sonnet!)
- Neutrino Oscillation Grant Application Sonnet
- A sonnet by Alex Howes
- Coda, a sonnet by George Barton
- Dr Lester's entry on Pseudoscalar Mesons (2012?)
