Readings for Physics 245A winter 2006 ================================================== ================================================== Note: The most recent reading appears first. ================================================== ================================================== Meeting 20 Tuesday, Mar. 14 For discussion at our last meeting, each group will make a short (10 min), informal presentation. Before Tuesday, each group will select one physics question to which its members would like to know the answer. Define the question as sharply as you can. Check that the answer is not already known! Outline your ideas for a research program (experimental, theoretical, or both) that could (in your lifetime) make progress toward an answer. Prepare a ten minute informal presentation to be made at our last class meeting next Tuesday. (Don't panic. I'm lot looking for or expecting something formal, elaborate, or polished---just some ideas to stimulate thinking and discussion.) ================================================== Meeting 19 Thursday, Mar. 9 Let's step back a bit and look at the larger picture. What is the standard model? How do our discussions of this quarter fit into the larger framework of the standard model? What are the strengths and weaknesses of the standard model? For what questions does it offer a satisfactorily understand answer? For what questions does it offer a satisfactory description? What are some questions that are "beyond the standard model?" Please add some of your thoughts on these topics to the Wiki. The material there is very good. I ask each of of you to make at least one contribution before our class meeting on Thursday. Also please come to class Thursday with your thoughts on the questions above. ================================================== Reading for meeting 18 Tuesday, Mar. 7 Hadron-hadron main points (JK) page 14 Leader & Predazzi Ch. 24 (or rather the part of it that I have copied for you and left in the usual place.) The topics are large p_T particles and jets in hadron-hadron collisions. This is physics for which we do have a fairly solid theoretical understanding. It combines what we know from deep inelastic eP and what you are learning in 230 about perturbative QCD. ================================================== Reading for meeting 17 Thursday, Mar. 2 Hadron-hadron main points (JK) pages 8-13 Leader & Predazzi sections 26.4, 26.6, 26.7, 26.8 Comments: So long as one keeps in mind that this is a collection of facts which are not yet understood, this reading is straightforward. I do not have any further comments. ================================================== Reading for meeting 16 Tuesday, Feb. 28 Hadron-hadron main points (JK) pages 0-7 Leader & Predazzi sections 26.1, 26.2, 26.3, 26.5, page 300 (Both available in the usual place.) For an update, I suggest hep-ex/0602021. Comments: Chapter 26 of L&P is modest in its aims. It describes the main features of the data and forgoes grander ambitions. Section 26.1 gives the high energy behavior of the total cross section. The gist of Sec. 26.2 is in Fig. 26.3. Elastic scattering has a diffractive forward peak which narrows as s increases. That means an effectively larger target. Section 26.3 and the note on page 300 are results on the phase of the elastic scattering amplitude. This shows that the elastic scattering amplitude is mostly real. That is, most of what is happening is absorbtion as opposed to phase shift, so a ``disk'' model is not a crazy 0th order picture. Section 26.5 just mentions diffractive dissociation. This is inelastic scattering that has some of the qualitative features of elastic scattering. These events are characterized by weak dependence on s, forward peaking, and a large rapidity gap between the p-bar and the X system of (26.5.1). ================================================== Reading for meeting 15 Thursday, Feb. 23 Peskin and Schroeder, Sec. 7.3 Handout in the usual place. Before discussing specific hadron-hadron processes, we will take a little time to look at some principles that are more general than any particular theory. The reading is a bit of a hodgepodge drawn from several sources. Here are the points to get (while avoiding excessive detail): unitarity of the S-matrix optical theorem partial wave unitarity Breit-Wigner resonance form Resonances as revealed in formation and production In Peskin and Schroeder, give your attention to the beginning and end of the section, and you can skip the center part on the cutting rules. ================================================== Reading for meeting 14 Tuesday, Feb. 21 Ho-Kim and Pham: Sections 10.4.2 and 12.6 Inelastic eP scattering pages 6-9 (handout) In Sec. 12.6, there is a bit more detail than we really need to deal with. The main point is that because the W couplings to different quarks are weighted differently than the photon couplings (just EM charge), it is possible to get from experiment different combinations of the quark distribution functions u(x), etc. An example is Eq. 12.68. ================================================== Reading for meeting 13 Thursday, Feb. 16 Now inward to deeper structure and inelastic e P scattering. Ho-Kim and Pham: Section 10.4.1 and first paragraph of 10.4.2 Inelastic eP scattering pages 1-5 (handout in usual place to appear late this (Tuesday) afternoon) ================================================== Reading for meeting 12 Tuesday, Feb. 14 We continue our probe of the structure of hadrons using photons. In e+e- annihilation, we have considered the kinematic region of timelike photons. Now we move to spacelike photons. We will do elastic scattering and then inelastic scattering. Ho-Kim and Pham Secs. 10.1 and 10.3. Hadron structure (handout available in the usual place) (Again, because our order of topics is a little different from when I wrote these handouts, some of the comments relating to order are wrong for this quarter.) I looked at an interesting, relevant, and very recent paper, hep-ex/0602017. I'm not at all sure what to make of it. ================================================== Reading for meeting 11 Thursday, Feb. 9 Now it's time for the resonances of heavy quark antiquark pairs seen in e+e- annihilation. Ho-Kim and Pham Sec. 7.6. e+e- annihilation resonances handout (available in the usual place). Leader and Predazzi Ch. 12 (available in the usual place). Most of what we will discuss in class is in Sec. 12.1. There is good physics in the rest of the chapter, but we probably will not be able to get into much of it in class. ================================================== Reading for meeting 10 Tuesday, Feb. 7 We will do e+e- annihilation next. First, off-resonance and then focusing on the resonances. Review your work in 230A on e+e- --> mu+mu-. Review Peskin & Schroeder Sec. 5.1 Review Ho-Kim and Pham Sec. 7.5. Read Peskin and Schroeder Sec. 17.2. Read e+e- annihilation handout (available in the usual place). (Because we are doing material in a different order, it mentions some things that we have not discussed yet.) Read new handout (in the usual place) containing two chapters: Ch. 9, Tests of the structure of QCD Ch. 10, Tests of the gauge structure of QCD Try to get the basic ideas in these without getting too bogged down in detail. Overall, this is pretty amazing. From a study of e+e- annihilation, just about the simplest process there is, one can get good experimental info on the number of flavors, the number of colors, the spin of the quarks, the spin of the gluons, alpha_s, and the gauge group. ================================================== Reading for meeting 9 Thursday, Feb. 2 Note: This is for THURSDAY. We will get into some good tests of the quark model: magnetic moments and mass splittings. Perkins Secs. 4.9 and 4.11 (in the usual envelop) Griffiths Sec. 5.10 (Since it looks like many of you have Griffiths or have easy access to it, I'm not supplying copies. However, if you need a copy, please let me know.) Ho-Kim and Pham Sec. 7.3 on mass splittings. Ho-Kim and Pham Sec. 7.4 Here the approach is to combine spin and flavor into SU(6). Long ago this was a trendy method. You don't hear much about it now. 7.4.3 does magnetic moments and is the main interest. Old "Ch. 4" handout pages 119-122. ================================================== Reading for meeting 8 Tuesday, Jan 31 Note: This is for TUESDAY. We will concentrate on the octet and decuplet baryons. Because mixed symmetry is involved, the octet is the hardest case. Also some of the questions that were raised today about the real world absence of particular representations will be addressed. Please note that one of the purposes of this section of the course is to help you get familiar with the most common known hadrons. The goal will be to know the hadrons of the four low mass multiplets (pseudoscalar and vector mesons and the octet and decuplet of baryons) along with basic info on quark content, approximate masses, and primary decay mechanisms. It is more important for the baryons than it was for the mesons to consider all parts of the states: space, spin, flavor, and color. 1) Review my handout on the quark model with particular attention to all four parts of the states and to pages 9-11 on baryons. 2) Related to color: Ho-Kim and Pham Sec. 7.5 Old "Ch. 4" handout subsections called Paradoxes of the simple quark model and color degree of freedom p. 123 and 124. 3) Ho-Kim and Pham Sec. 7.2.5 on baryons. ================================================== Reading for meeting 7 Thursday, Jan 26 Sections 7.1 (more I-spin) and 7.2 (quark model) (in Ho-Kim and Pham) Quark model main points and quark model handouts (in envelop by my door) (I also threw in an I-spin example that's on top of each packet. It might be helpful in the next problem set. Sec. 4.5 of Griffiths might be similarly useful.) A.2 and A.3 from "Appendix A" of the earlier handout. From the earlier "Chapter 4" of the handout: Review the SU(3) part of Sec. 4.2 Skim Sec. 4.3 4.4 up through the top of page 119. This is very important stuff---the basics of the quark model. The goal is to become familiar with the particles of Fig. 7.2 and their properties. ================================================== Reading for meeting 6 Tuesday, Jan 24 Chapter 6 (in Ho-Kim and Pham) Isospin, etc. ================================================== Reading for meeting 5 Thursday, Jan 19 Chapter 5 (in Ho-Kim and Pham) Symmetry and Internal symmetries (optional handout in envelop by my door) As you read, try to emphasize the phenomenological implications of the symmetries and deemphaisze the field theory formalism, which you will see in 230 also. ================================================== Reading for meeting 4 Tuesday, Jan 17 Handout on rotation matrices Handout on Lorentz and Poincare groups Both of these are available by my office door. ================================================== Reading for meeting 3 Thursday, Jan 12 Symmetry is the topic for the next few times. It has played a very important role in particle physics. It is particularly useful when it is all you have---that is, when you do not yet know the correct theory. Also, it can save you a lot of work even when you do know the theory. Furthermore, it can provide a very satisfying understanding of some results which might otherwise be seen as only a curious coincidence in the output of a mechanical calculation. The reason for all of this is the close connection between invariance and symmetry on the one hand and selection rules, conservation laws, and relations among amplitudes on the other. The classic example of this connection is Noether's theorem. The mathematics of symmetry is group theory, so we begin with some discussion of that. My favorite books and the ones that I use when I teach 223B are Tung and Georgi. Unfortunately, we do not have the luxury of devoting all quarter to the subject. We will begin with a general group theory. From there, we will move on to the Poincare group, internal symmetries, and the quark model. Outside my office, in an envelop marked 245A, you can find copies of some reading on group theory. There are two items in each paper clipped packet. The first is marked "Appendix A Elements of Group Theory." Call it Appendix A. The second is "4 Group theory and the quark model." Call it Chapter 4. Reading: A.1 from "Appendix A" of the handout. 4.1 and 4.2 from "Chapter 4" of the handout. Notes on Lie groups on our website. Lie groups and Lie algebras on our website. ================================================== Reading for meeting 2 Tuesday, Jan 10 Kinematics: Collision and decay kinematics (handout) Cross section, S-matrix, phase space: Section 4.2 (in Ho-Kim and Pham) Section 4.5 (in Peskin and Schroeder) Accelerators and detectors: Chapter 3, Experimental Methods, (in Particle Physics, Martin ad Shaw, 2nd. ed., handout) Accelerators and detectors (on our website) Note: Physics 252B does all this in much more detail. Also do the reading for meeting 1 if you have not done so already. For further reference and depth on the topics above, check the following items. Additional information on kinematics, cross sections and phase space: http://pdg.lbl.gov/2005/reviews/contents_sports.html --> Kinematics Section 12 in http://www.arxiv.org/pdf/hep-ph/9507456 There is a three page summary of many accelerators in http://pdg.lbl.gov/2005/reviews/contents_sports.html --> Accelerator physics of colliders. (The second section of this also defines the all-important luminosity.) A basic description of the accelerator chain at Fermilab: http://www-bd.fnal.gov/public/chain.html More depth on detectors: http://www.jlab.org/~hcf/detectors/detect04_html/sld001.htm Slick Powerpoint show on basic high energy physics, CERN, and the LHC. http://lifshitz.ucdavis.edu/kiskis/phy245a_06/lhc.ppt Basic info on high energy physics, CERN, the LHC, and the CMS detector http://lifshitz.ucdavis.edu/kiskis/phy245a_06/cms.pdf (The links to the originals of these two appear to be dead at the moment.) Paper on LHC status: LHC Expectations (Machine, Detectors, and Physics) http://www.arxiv.org/pdf/hep-ex/0512007 ================================================== Reading for meeting 1 Thursday, Jan 5 Introduction (available on our website) Overview (available on our website) Chapter 1 (in Ho-Kim and Pham) ==================================================