Announcements for Physics 752 (Prof. Agashe) - Spring 2014

 

 

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

 

(1). Details of term paper to be written/presented by you are here.

 

Tentatively, we will have presentations of term paper on May 19 (Monday) and if needed on May 20 (Tuesday) and the actual term paper will be due Wednesday, May 21.

 

(2).  The last two HWs:  9 and 10 (on Standard Model phenomenology) have been assigned here and are due on Monday, May 19.

 

Some comments on previous HWs:

 

(i) Note that in HW 4.2, you are to study only the case of vector-like coupling of electron to photon.

 

(ii) zeta-zeta scattering in exercise 13.14 from LP (HW 3.3) means 2 zetas in both initial and final state, just like eta-zeta scattering in HW 3.4 (i.e., Fig. 13.2, exercise 13.15 from LP) means zeta and eta in both states).

 

(iii) Some comments have been added to HW 5.2.1 and 5.3.3, but there is no change in what you are actually supposed to do

here.

 

(iv) HW 8.5 is somewhat complicated/long, but several hints are given along the way.

 

(3). There will an extra lecture on Friday, May 2 at 11 am.

 

(4). Solutions to HW 1 through 4 are now posted here.

 

(5). Plan for lectures starting April 14: 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:

 

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

 

- then we will gauge these symmetries and discuss the classical theory (sec. 14.1 to 14.4 of LP)

 

- finally, quantization of non-abelian gauge theories will be 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 will discuss spontaneous breaking of a global symmetry (section 13.4 of LP).

 

- above model will be shown to have massless scalar particle (called Nambu-Goldstone boson): we will discuss nature of its Interactions (section 13.5 of LP).

 

- finally, gauge 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.

 

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

 

(6). Please try to print and fill out the feedback survey here 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). A few of notes have been posted:

 

(i) The argument form Weinberg's QFT book about why a superposition of the 2 minima for a discrete symmetry model [sec. 13.4.1 and Fig. 13.1 (b) of LP] is not the ground state is here.

 

 (ii) In the lecture on March 24, I discussed the relation between the models with explicit gauge boson mass term vs. spontaneous breaking, involving fermion-coupled to gauge boson in 2 ways  (what I called "closing the circle"). This issue is somewhat subtle and so (detailed) notes are posted here.

 

(iii) Calculation of decay of Z boson into fermion and anti-fermion is here.

 

(iv) Electron-positron annihilation into muon and anti-muon is here.