47. Planck 2008: First and second days
DmitryGreetings from sunny Barcelona! Luckily, internet connection is on both in the hotel and at the conference hall :), so allow me to give you a brief report of what I’ve heard today and yesterday.
The overall spirit of the conference is pre-LHC anxiety. The number N of new theoretical ideas in hep-ph discussed at the conference is not >> 1, among the most interesting new ones are definitely unparticles with talks devoted to the topic yet to come (tomorrow, I think). Also, my personal impression is that the name of the game in phenomenology today is flavor theories. The reason is that flavor violating processes are much more sensitive to new physics than EW precision test, and this new physics is what naturally bothers phenomenologists waiting for LHC data.
So, the opening talk was by Anrzej Buras from Munich, who explained in his lightning speed review where to expect this new physics in flavor violating processes.
From his point of view, there are three most interesting extensions of the SM which lead to something interesting in FV processes at LHC energy scale:
1. MSSM with non-minimal flavor violation
2. Littlest Higgs models with T-parity viol.
3. Warped extradimensions aka Randall-Sundrum phenomenology (well, new physics following from RS appears not quite at the LHC energy scale but at the scale of order of 4 TeV or larger (20 TeV) instead; that makes RS less interesting extension of the SM for people who are looking for fast new results)
All three of them are more or less ugly theories of flavor in the following sense: take SM, it has 28 free parameters, 22 of them are in the flavor sector. After fixing masses of quarks, we essentially have 4 parameters. RS flavor theory adds new 18 real parameters and 9 complex phases, MSSM with NMFV is even worse in this respect.
He empasized that there exists RG enhancement of new physics in the processes involving 
.
Next, Matthias Neubert (Mainz) and Czaba Csaki (Cornell) were focused on Randall-Sundrum flavor theory. Let me remind you that interesting flavor physics appears in RS as follows. One puts fermions in the bulk and Higgs field on the brane, Yukawa couplings are exponentially suppressed (RS solution of the hierarchy problem). If one correctly writes all the terms in 4d largrangian, it turns out that fermion modes are not orthogonal anymore, which leads to the flavor violating processes.
During the coffee break I talked to Slava Rychkov about Migdal-Makeenko loop equations (completely off-topic for the conference, but topic of the great interest to me). Slava started his career as string theorist (he has two papers with Polyakov about loop dynamics and AdS/CFT) but currently he (I feel) completely turned to the phenomenological side. This paragraph is a reminder for myself to write a couple of posts about loop dynamics (this topic is actually related to 3D Ising, too).
I decoupled completely after the coffee break since I felt I have to devote some time to dS :)
After the lunch cosmology oriented session started.
Licia Verde (who is new faculty at Barcelona) was talking about recent WMAP results. Gosh, what a great talk! In fact, she discussed more than WMAP5 - recently there was ACBAR 08 data release (Reinchardt et al., 2008 - > 3 acoustic peak data) and QuAD data release (Pryke et al., 2008 - polarization data). As she says, WMAP5 + ACBAR08 data are now as good as adding LSS and SN data to WMAP5. I think I also understood the origin of consipracy in WMAP5 data regarding the new mask they use for non-gaussianity detection (let me remind you, that it covers less sky than the mask used in WMAP3). I will write about it more later.
Tony Riotto from CERN prepared a mind-blowing coctail named “Theoretical ideas in cosmology”. Among huge number of things he discussed a couple were especially interesting for me: a) Grocce-Scoccimarro diagrammar for LSS (how to take into account growing non-linearities in the LSS dynamics) and b) stochastic approach to LSS. After his talk, I entered a discussion with him regarding Grocce-Scoccimarro RG methods applicability which hopefully will lead to a separate post on this blog. Again a reminder for myself :)
Jaume Garriga was talking about bigravity and was brutally attacked by Gia Dvali, who was claiming that Garriga?s model is inconsistent with cosmology. The base of his argument was existence of massive graviton in the model with a large mass (much larger than H) which leads to a number of inconsistencies.
I had impression that in addition to massive graviton Garriga also had massless graviton which would be responsible for correct large scale behavior, LSS etc., so that would resolve the issues Dvali mentioned, but I might be wrong here.
After his talk, I left feeling that I really really have to work and be productive today :)
Tuesday
The very first talk was by Gia Dvali and naturally it was about his recent work on theories with large number of species and gravity cutoff in such theories (as you may remember, I wrote about it before on the blog). Recall that, as he claims, gravity cutoff in the theories with large number of species is
,
where N is the number of species. One example of this relation is the theories with large extra dimensions, where N is the number of KK modes 
. When I first read Gia Dvali?s paper, I thought that the idea is extremely beautiful, now I should admit my feeling has dramatically changed. The reason is that Dvali uses large number of species
to explain another large number 
. Compared to warped extradimensions, I feel that beauty of hierarchy solution problem is lost.
Next, Steven Abel from Durham discussed metastable SUSY breaking (in this point, I was lost for the conference since a couple of integrals I was calculating started to make sense :))
Neil Spooner told us about undergraund particle experiments and Jon March?Rassell from Oxford ? about spectroscopy of WIMPonium ? unstable bound state of WIMPs.
After interesting discussions with Konstantinos Dimopoulos and David Lyth I decopled for the rest of the day, since de Sitter physics kept bothering me :)
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