Wednesday 21 January 2009

HEP 2008 chart

Symmetry Breaking just posted the 2008 topcites according to SPIRES. That list is a bit depressing to look at, as it is dominated by papers from the last century. Recent ideas cannot stand ground against Maldacena, Randall-Sundrum, ADD. To check what's new in town, instead, I compiled another ranking of most cited papers FROM 2008. I counted the ratio of the number of citations to the number of months the paper has been out. (I was too lazy to count days, which would be more adequate. Also, I included only the papers that have already acquired 50+ citations). Here is what's revealed.
  1. 70 citations/month, Five-Year WMAP Observations: Cosmological Interpretation, by WMAP Collaboration, arXiv:0803.0547
    The absolute leader, even though they were hardly the news last year: one needs very large telescopes to tell the 5-year results from the 3-year ones. Nevertheless, quite deservedly, they keep receiving the credit for turning cosmology into a precision science.(Actually, there should be two more WMAP clones in this list: arXiv:0803.0586 and arXiv:0803.0732 who have received 32 and 22 citations/month respectively, but these two got disqualified for obscuring the view.)
  2. 26 citations/month, N=6 superconformal Chern-Simons-matter theories, M2-branes and their gravity duals, by Aharony, Bergman, Jafferis, Maldacena, arXiv:0806.1218.
    So this is the most cited 2008 theory paper... It constructs novel gravity duals that employ the notion of M2 branes. I have no idea how important this is. Go ask Jacques, who has a post on the Bagger-Lambert construction of M2 branes, and another one that includes a brief comment on the Aharony et al. paper.
  3. 26 citations/month, Observation of an anomalous positron abundance in the cosmic radiation, by PAMELA collaboration, arXiv:0810.4995.
    PAMELA was definitely the star of the last summer: the paparazzi affair was more widely discussed than Britney Spears' new look. On top of that, PAMELA's observation of a cosmic-ray positron excess in the energy range 10-100 GeV was readily interpreted as an indirect signature of dark matter annihilation/decay. This spawned a whole lot of theoretical activity, including the paper below.
  4. 19 citations/month, A Theory of Dark Matter, by Arkani-Hamed, Finkbeiner, Slatyer, Weiner, arXiv:0810.0713.
    Once again Nima set the direction. The paper proposes a model that explains the PAMELA excess and a few other mysterious astrophysical results. The crucial feature is the hidden sector hosting dark photons (cool name) with GeV scale masses.
  5. 16 citations/month, Superconformal Chern-Simons Theories and AdS(4)/CFT(3) Correspondence, by Benna, Klebanov, Klose, Smedback, arXiv:0806.1519.
    It is a new development related to the Aharony et al (number 2 on this list) who in turn is a new development related to the Baggert-Lambert construction of M2 branes...
  6. 13 citations/month, Averages of b-hadron and c-hadron Properties at the End of 2007, By Heavy Flavor Averaging Group, arXiv:0808.1297
    That must be very important, even if Heavy Flavor Averaging Group sounds a bit ominously.
  7. 12 citations/month, M2 to D2 revisited, by Ho, Imamura, Matsuo, arXiv:0805.1202.
    It's a pity there is no R-branes yet in string theory; R2-D2 would make an even better title.
  8. 12 citations/month, M2-branes on M-folds, by Distler, Mukhi, Papageorgakis, Van Raamsdonk, arXiv:0804.1256I'm afraid I have run out of jokes on M2 branes. Given that I have no intelligent comments in store, I'll just skip to the next one.
  9. 11 citations/month, Three-flavour neutrino oscillation update, by Schwetz, Tortola, Valle, arXiv:0808.2016.
    Nobody expects the Spanish Inquisition...people out there are still working on neutrinos...
    Congratulations to Thomas - the only CERN theorist (now ex-) who has made it to this ranking.
  10. 11 citations/month, Bagger-Lambert Theory for General Lie Algebras, by Gomis, Milanesi, Russo, arXiv:0805.1012.
In summary, 2008 in particle theory was the Baggert-Lambert year :-|. Way down below (6 citations/month) is the paper of D.T. Son on AdS/cold atoms correspondence, which I personally consider the most interesting one in the last year.

Update: It was pointed out to me that R2D2 is already on ArXiv :-/

Friday 16 January 2009

Into 2009

With two weeks delay I'm entering the 2009 blogging. This is going to be a very important year for particle physics since it is the year of the first collisions at the LHC. If you're feeling deja vu, that's OK, I wrote the same thing in January 2007 and 2008 :-) I'm afraid I may have to write it once more next year...

Meanwhile, two important events have happened in the world of particle physics. One is that Resonaances has turned two years old, which is the age when children start forming simple sentences. The other is the peaceful handing of power at CERN. The former Director General Robert "Cauchemar" Aymar stepped down to the applause of a crowd waving white handkerchiefs. The professional handling of the LHC meltdown crisis earned him a lot of esteem and should open him the door to a political career. The rumor is that he will head the Ministry of Disinformation and Denial at the French government.

What do I hope for in 2009? It is clear that even if the LHC is switched on this summer there's no chance for interesting results by the end of the year. Since there's no hope here on Earth once again we should look to Heaven, as there are long-expected results in astroparticle physics due in 2009. Personally, I'm dying to see the first GLAST results. GLAST is a satellite gamma-ray observatory whose name, for conspiracy reasons, was recently changed to FERMI, and now it is often referred to as GLAST-now-FERMI, or as FERMI-former-GLAST, or as G-FERMI, or otherwise (though, interestingly, almost never as FERMI). The high expectations for that mission got even more amplified by the positron excess reported last year by PAMELA and ATIC. If that is due to dark matter, there may well be signatures in high-energy photons too. In fact, previous gamma-ray experiments like EGRET and HESS have reported some unexplained excess. GLAST-now-FERMI will probe the gamma rays in the range 30 MeV - 300 GeV with a better sensitivity than the previous experiments. Furthermore, to some extent they can also confirm or rule out the positron excess reported by PAMELA/ATIC. The rumors that are currently flying in the air are a bit disappointing ... but let's wait. Whatever the outcome, the name of FERMI/GLAST will make a lot of appearance on blogs this year. Unless they change the name to Lancelot-of-the-Lake.

Apart from indirect detection in cosmic rays experiments, there is going to be some progress in the direct detection experiments. In the recent two years a tremendous jump in sensitivity was achieved by the XENON experiment at Gran Sasso and the CDMS experiment at Soudan mines. The XENON experiment is expected to publish new results this year that will push the sensitivity down by another factor of ten, probing the spin-independent dark-matter-nucleon cross section of order $10^{-45} cm^2$. Since dark matter is certainly out there we must it one day. So why not this year?

Finally, don't forget to cross your fingers on April 12, as the PLANCK satellite is going to be launched on that day. Interesting times ahead.