Elementary Particle Physics Fall Term Course Information

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1 Physics 145 Harvard University Elementary Particle Physics Fall Term 2014 Course Information Instructors: Gary Feldman, Professor, Lyman 232, , Teaching Fellow, Stephen Chan, Palfrey House 2 nd floor, , [email protected] Course Goals: I have three goals for this course, which are somewhat different from the goals of a typical undergraduate course. 1. Elementary particle physics is the most fundamental science in that it addresses the laws of nature in their most basic form. It asks What are the most basic particles and how do they interact with each other? We don t know the complete answer to these questions, but what we do know reveals a subtle, non-intuitive scheme, with both symmetry and diversity. The first goal is to have you understand this scheme and rich phenomenology at a conceptual level. Because they will be necessary to understand the formalism, we will do some calculations, but the primary goal is not to leave you with a set of calculational tools. They can come later, if you decide to continue the study of particle physics at a graduate level. 2. Most undergraduate courses are rather impersonal. The instructor gives lectures; the students take notes; and they only occasionally ask questions. It is quite possible for the instructor never to learn the names of a majority of the students. Since this course traditionally attracts a smaller number of students, it is ideal for a format in which there is more give and take during the lectures and through seminars. This is the reason for setting up the classroom so that everyone can sit around the table. 3. Most undergraduate courses proceed largely as a mathematical deduction from a few principles. The experimental nature of physics gets lost in the rush to present the theory. Particle physics is an ideal subject for emphasizing that physics is an experimental science for two reasons: (a) it is one area of physics in which we do not yet know all the fundamental laws, and (b) much of the progress in the field has come from experiments done in the past fifty years. To this end, all or most of you will present a classic paper in a seminar toward the end of the course. These seminars will emphasize not only the significance of the results, but the methods by which the experiments were done, and the experimental problems encountered and overcome by the experimenters.

2 Course Information Page 2 Seminar Limitation: We will only have time for twelve student seminars, and for that reason twelve students would be the ideal size of the class. If the enrollment is over twelve, the additional students will write a paper in lieu of giving a seminar. Prerequisites: The main tools we need are those of quantum mechanics and special relativity. We will use the concepts of quantum mechanics constantly, and I will expect you to have a good knowledge of the material of Physics 143a. Knowledge of at least some of the material from Physics 143b will be quite helpful, but is not essential. In particular, the addition of angular momenta is important, and some of you may have to do a little extra work to either learn this or refresh your understanding of it. One or two section meetings will be devoted to this subject. We will spend one or two lectures on special relativity because your preparation from Physics 15 is probably not sufficient for what we will need. This will also be an area in which you will have to spend some extra time in drill on the calculational techniques and some time in section will be devoted to this also. Course Meetings: This course uses what I call flexible scheduling. It works in the following way. The course blocks out MWF from 10 to 11, and TT from 7:30 to 9pm. It is essential that all students have these time periods free. (We will discuss at the first class meeting possible rescheduling to meet student s schedules.) The MWF periods are primarily for lectures; the TT periods are used primarily for sections and seminars, with all course meetings in Jefferson 453. Sections will normally meet Tuesday evenings. The flexible part comes in as follows: I need to be away occasionally for research reasons. Normally, I will lecture on all MWF that I am in town. On weeks that I have to be away during a normal lecture day, I may try to use one of the evening slots for a makeup lecture. You should be warned that near the end of the term, when seminars are being given, we will normally meet every day of the week. The one compensation is that I promise to finish all of the required lectures and seminars by the start of reading period. When we have seminars, we will have two per evening. There will be a maximum of fourteen seminars (i.e., seven evenings), one given by me, one by Stephen, and twelve by members of the class.

3 Course Information Page 3 Both the lectures and seminars are integral parts of the course, and I expect all students to attend and participate in them. (In past years, I have sometimes based part of the final on the seminar material.) The section meetings are designed to enrich the material presented in the lectures and seminars, and to help students with material with which they are having difficulty. Students should attend section meetings to the extent that they feel they are useful. Office Hours: Stephen and I will decided on office hours after going over the schedules on the questionnaires, but students should feel free to drop in any time or make an appointment. Secretaries: My administrative assistant is in a state of transition. I will add the particulars here when I get the information. If I am not around, there is an outside chance that the AA will know my schedule. Problem Sets: There will be occasional problem sets (not more often than once a week). They will be due at the first class meeting that occurs at least one week after they are handed out. Stephen will distribute solutions when the corrected problem sets are returned to you. There will be a penalty for late problem sets and no credit will given for problem sets turned in after solutions have been made available. As in any physics course, the problem sets are extremely important for mastering the material. They are primarily for instruction, rather than evaluation (although they will count as part of your grade as an additional inducement for you to do them). Thus, you may collaborate on them and you many seek help from any source. However, you must write up your own work.

4 Course Information Page 4 Evaluation: There will be an inclass midterm examination (date to be announced later), and a takehome final examination. You will give a 30 minute seminar, or write an equivalent paper, as discussed above. The course grade will be based on the following components: Problem sets 20% Seminar (or paper) 30% Midterm 20% Final 40% The astute student (and I assume that all of you fall into that category) will notice that the total comes to 110%. The category with your lowest grade will count 10% less. In other words, if your lowest grade is on the midterm, it will only count 10% for you. Web Page Everything of interest will be posted on the web: lecture notes, handouts, problem sets and their solutions, the course calendar, seminar transparencies, useful links, etc. The URL is Texts: The main text for the course is Introduction to Elementary Particles, 2 nd Ed. by David Griffiths (Wiley-VCH, 1987). Griffiths is a master textbook writer. My lectures will probably follow Griffiths most closely, especially in the early part of the course, simply because the best way to present the material is usually the way Griffiths has chosen to do it. The second source book for the course is The Experimental Foundations of Particle Physics, 2 nd Ed. by Robert Cahn and Gerson Goldhaber (Cambridge, 2009). Cahn and Goldhaber is a collection of classic particle physics papers along with some introductory explanatory material. Many of the seminar papers will be found here. A recommended book that you may wish to consider purchasing, depending on the state of your finances, is, Introduction to High Energy Physics, 4th Ed. by Donald Perkins (Cambridge, 2000). Perkins is not as strong on the theoretical or conceptual basis of

5 Course Information Page 5 particle physics as Griffiths, but contains more details on particle physics phenomenology than Griffiths does. Other books of interest are: Modern Elementary Particle Physics, (either edition) by Gordy Kane (Addison-Wesley, 1989, 1993). A somewhat different approach. He starts with the ending point of our course and works backwards. He argues this is the way one teaches electrodynamics. One starts with Maxwell s equations and derives their consequences. Actually, it is not the way I teach electrodynamics and I decided that it was not the best way to teach undergraduate particle physics either. However, you might find it interesting and useful. Introduction to Experimental Particle Physics by Richard Fernow (Cambridge, 1986). An excellent book on detectors and experimental techniques. You may find it a useful reference for you seminar preparation. Quarks and Leptons: An Introductory Course in Modern Particle Physics by Francis Halzen and Alan Martin (Wiley, 1984). A good graduate-level text. Concepts of particle physics by Kurt Gottfried and Victor F. Weisskopf (Oxford, 1984). An older book in two volumes. Volume 1 gives good insight into many issues of particle physics in a less quantitative and formal way than Volume 2. The BaBar Physics Book, SLAC report number SLAC-R-504, October, This is will be of particular interest to the one of you who does the seminar on CP violation in the BB system. I have asked both Cabot Science Library and the Physics Research Library to put all the above books on reserve (although Cabot refuses to put non-required books on reserve). I have also asked the Coop to order Griffiths, and Cahn and Goldhaber. You can probably obtain copies from online merchants more cheaply. Finally, there is a marvelous little booklet that is the constant companion of every particle physicist, the Particle Properties Data Booklet. If you wish, you can order a copy of the 2012 edition of this booklet, and pre-order the 2014 expanded version of it called the Review of Particle Properties, and the 2014 booklet. These are available free and can be ordered online at Once you get on their mailing list,

6 Course Information Page 6 you will get updates every two years, forever. All of this information is also on-line at and can be linked from the course web pages. A copy of the Review of Particle Properties is also on reserve in the Physics Research Library. inspire: For your seminar, you will probably want to use the inspire database for bibliographic searches. The link to it ( can also be found on the course web pages. Course Syllabus: The following is the way the course developed the last time I taught it in It will probably be similar this time, but I may move some material around, add some things and omit others. Lecture Topic 1-5 History of Particle Physics 6-8 Overview of the Standard Model 9-13 Symmetries 14 Relativistic Kinematics Detectors and Accelerators Feynman Calculus Dirac Equation 23 Quantum Electrodynamics Deeply Inelastic Scattering 26 Quantum Chromodynamics Charged Weak Interactions 30 Flavor Oscillations Neutral Weak Interactions and Electroweak Mixing Gauge Theories and the Higgs Mechanism