A slow one

Hi there.

This week even is was exciting, was very slow.

In the particle course we introduce the quarks in stage...more or less trivial after spendt couples of weeks on the lepton sector, the only non-trivial issue is to assure the no Flavour-Changing--Neutral-Currents or (FCNC).

But, What does FCNF means?

From the GWS (Glashow-Weinberg-Salam) model the exchange of a neutral boson (as the Z), cannot changing the flavour of the quarks (nor leptons). So, that's it, a neutral current (particle) couldn't change the flavour -----> no FCNC.

Thus, the flavour changing must be carried just by the charged bosons (W).

The answer to this problem began with Cabbibo, who suggested that d and s quarks were mixed. Later, Glashow-Illiopoulos-Maiani suggested the existence of another quarks rather like the u, it was called charm or c. Still a mixing between d and s should be there. Finally, the inclusion of the 3rd generation of quarks (b and t), enhanced the mixing of the ``down"-like ones by a 3x3 matrix, known as the Cabbibo-Kobayashi-Maskawa matrix.

Moreover, the inclusion of this matrix overpass the expectancy, 'cause additional to the quark mixing it contains a physical phase, which implies the CP violation.
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On the other hand, the Renormalization Group is turning interesting.

I'm reviewing the Wilson's approach to the RG. This a nice subject. Despite my taste, a good book to introduce the subject is ``An introduction to Quantum Field Theory'' by Peskin and Schoeder.

In the very introduction to the subject the authors link the RG to the construction of effective theories, giving you a procedure to eliminate the irrelevant terms.
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Changing theme. I'm trying to understand a paper of the RG flow in gravity theories. Happens that one of the professors, whose research goes in that direction, was in the Villa de Leyva School 2007... which I should reject on behalf of my qualifying examination. Jesus...!!!

Ok, That's it for the week. C U.

After a long time

Hello! What a long time...!!!

Well, but finally I'm back. This week was very interesting. Finally I did my first electroweak calculations.


So, the low energy scattering of leptons is a studied stuff... As well a the high energy behavior of the electron-positron annihilation.

Also, the renormalization group seems to be a not so difficult subject. Of course I reviewed a lot of renormalization and dimensional regularization in order to finally get the ideas of RG. And easy picture of the renormalization group is just the pass through different scales for describing the same set up, my favorite example is that one can get the thermodynamics from statistical mechanics. Other example is the spin chain, you can describe it spin by spin or macroscopically by taking block of spin and average over the block. Important: One can go from the micro to the macro, but not the other way around... this is because when you average lose information about the individual spins or micro-states.

Ok... it was just a bit of the week. I'll write more next week, 'cause I'm tired today. Cya.