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Hep

Open questions and next week program
Some open questions from last time :
- Quantum corrections to scalar mass in DR. For this topic, it would be nice if everybody could do the following exercise : take a toy model with a scalar phi and a fermion psi, coupled with a yukawa ; and phi^4 self-couplings for the scalar.
Compute the whole correction (finite and infinite) in both cutoff and DR to the scalar mass when the fermion is heavier.
- Phase space for 2 & 3 final particles ; phase space suppression.

New topic : CP violation is SM
- Chapter 6 of Barbieri.
- Where is CP violation observed.
- CP is conserved for SM with two families. Find the diagrams which contribute to a CP violating process involving Kaons (direct or indirect).
Posted by Jan Mrazek at 10:26
Hierarchy Problem & SUSY
An interesting topic to be discussed in the next weeks is how supersymmetry could solve the gauge hierarchy problem. Roughly speaking the idea is that due to the additional symmetry, quadratic divergences should cancel between the bosons and fermions.

An interesting approach to this is presented in Polonsky's Book: Supersymmetry: Structure and Phenomena. (A preprint version can still be found on arXiv.) In the chapter 3, the author follows a bottom-up approach: he is constructing a theory in which all the quadratic divergences are set to cancel. He then shows how this can be related to SUSY.
Posted by Claude Becker at 14:01
Topics discussed so far
23/Oct: Is there a new physics between electroweak and Planck scales? (Jan)
30/Oct: Is there a new physics between electroweak and Planck scales? [continued] (Jan)
06/Nov: Brans-Dicke gravitation (Daniel)
13/Nov: Brans-Dicke gravitation [continued] (Daniel) & Gauge Hierarchy Problem (Claude)
20/Nov: Hierarchy Problem using Dimensional Regularization (Alessandro)
27/Nov: Barbieri "Ten Lectures on EW Interactions" [Sections 1-4] (Claude & Marc)
04/Dec: Barbieri "Ten Lectures on EW Interactions" [Sections TBA]
Posted by Claude Becker at 18:38
Topics to be covered in the future
* Accelerator Theory (presented by experimentalist from 6th floor)
* Coleman-Weinberg paper
* Strong CP problem
* Renormalization group: Standard vs. Wilsonian approach
* How is SUSY supposed to solve the Hierarchy Problem?
* finish discussing gauge hierarchy problem within dimensional regularisation
* . . .
Posted by Claude Becker at 17:18
Tue 6. Nov
Daniel is going to present Brans-Dicke theory of gravitation.

We will mainly discuss the first paper.

But, I also recommend the second one, quite interesting.

cya
Posted by Claude Becker at 17:16
After first meeting
So this morning we had the first real meeting. In my opinion it was interesting, and I really think it is a good point if Oleg or any other senior physicist could come.

Now we have to decide what to do the coming weeks ; it would be good if we knew more in advance what will come (I apologize for this time). I also think this blog is a good place to write down what happens.

Next week we will for sure finish the discussion about Misha's paper, meaning in particular the introduction of his model.
Other topics which will be covered :
- Coleman & Weinberg
- "Affleck-Dine gravity" ; proposed by Daniel

For me it would be interesting to look also in more details at other scenarios for BSM ; in particular those which are not studied by any group here at EPFL. I think at :
- GUT : look at one example just to get a more precise idea
- Technicolor
- Little Higgs

I think I have written enough for my first post ; please react and propose other topics.

MVH

Jan
Posted by Jan Mrazek at 13:21