Announcements for Physics 752 (Prof. Agashe) - Spring 2017

(0). For all homeworks, please read carefully the statements of problems, especially since notes/hints have been given in many places.

(1). HW 7 (due April 12, Wednesday, during lecture) on non-abelian gauge symmetries at quantum level and HW 8 (due April 26) on SM theory are assigned here.

(2). HW 9 and 10 (last ones for this course) on SM phenomenology also have been assigned here and are due May 3 and 10 (respectively).

(3). Solutions to HW 1-7 are posted here.

(4). Term paper presentations (slides preferred) will be 10 am. to 3 pm. (with 1 hour break for lunch) on May 15 (Monday) and May 16 (Tuesday): 4 on each day.

Write-up (at least 10 pages long) will be due Wednesday, May 17 by 5 pm.

(5). Some notes (two on QCD and one on Z decay width) are posted here.

(6). Please try to print and fill out the feedback survey here (2 pages) and return it to me (without your name on it) during lecture: this is just to help me improve teaching: thank you very much in advance for doing this!

(7). Plan for lectures starting March 27: we will use the 3 QFT topics that we studied so far to first construct the standard model and then study its phenomenology (based on chapter 15 of LP, supplemented by other references that I will give as we go).

The topic that we finished just before was non-abelian gauge theories [needed for describing both strong and weak (nuclear) forces]:

- first, we considered global symmetries (sec. 13.2 of LP), including their spontaneous breaking (sec. 13.4.3)

- then we gauged these symmetries and discussed the classical theory (sec. 14.1 to 14.4 of LP): their spontaneous symmetry breaking was studied based on Peskin, Schroeder (PS)’s pages 692-694

- finally, quantization of non-abelian gauge theories was studied (sec. 14.5 of LP)

The even earlier topic of Higgs mechanism is needed for describing weak (nuclear) force within the SM: the outline here was

- first, we discussed spontaneous breaking of a global symmetry (section 13.4 of LP).

- above model was be shown to have massless scalar particle [called Nambu-Goldstone boson (NGB)]: we also discussed nature of its Interactions (section 13.5 of LP). Existence of such NGB’s in general (i.e., Goldstone’s theorem) was proven following PS pages 351-352

- finally, we gauged the above global symmetry section 13.6 of LP) to find that the corresponding gauge boson acquires mass (and Nambu-Goldstone boson "goes away") and theory remains renormalizable: for this purpose it was crucial to argue that there is no dependence on gauge-fixing parameter in the total amplitude for a process (see PS pages 734-739).

Finally, the 1^st QFT topic was renormalizability of QED, based on chapter 12 of LP.