## Sunday, December 26, 2004

### LHC looks fine

No news are often good news. Usually we don't write about them. Let's make an exception.

The LHC should be finished in 2007, and right now it seems very realistic. (This good news contrasts with the Tevatron that was recently stopped for quite some time.) The British have finished the first of four barrels that will form the core of the SCT (SemiConductor Tracker) - see a very informative article at
The LHC needs a new computing grid: it will create 10 petabytes of data every year. If you don't know what a petabyte is, you may like the translation of BBC: 10 million CDs of data per year. ;-) Also, the Fermilab and the Berkeley labs announced that a key U.S. component for the LHC has been completed:
Note that these cryogenic distribution boxes are produced by a woman-owned company Meyer Tool and Manufacturing. The total U.S. contributions to the LHC are roughly half a billion USD.

The Russians also want to be active:
Imagine, 2007 is not too far. The articles above talk about the Higgs and perhaps even mini-black-hole production. :-) Well, Steven Weinberg has a nightmare like many others - namely the simplest version of the single-Higgs Standard Model - while Nima Arkani-Hamed proposes that his particular models of the stringy landscape will be seen at the LHC:
There are other, perhaps more conventional scenarios, too. For example, it is not ruled out that the antisupersymmetric (but not necessarily unstable or tachyonic!) people like Peter Woit only have 3 years left before they will have to move to their restrooms and spend the rest of their lives there. ;-) Although one should note that the experiment ATLAS plans to exploit the data for 10 more years.

The Linear Collider

Just an update that many of us did not know: the next linear collider is probably going to be called The International Linear Collider (ILC). In the summer it was more or less decided that it should be based on the cold, superconducting technology:
The price will be above 5 billion dollars, and electrons and positrons will smash after being accelerated in 10-mile-long pipes. Note that according to the picture used by BBC, the ILC will experimentally discover the Calabi-Yau manifold.

If you enjoy these BBC news about the accelerators, here's another about the LHC construction and about 50 years of CERN:
Finally, you may want to know that in March 2004, Peter Renton from Oxford made another advertisement for the idea that LEP has seen that Higgs at 115 GeV:
Concerning the Higgs at 115 GeV, one should not forget about John Ellis' calculations of such a Higgs based on Odysseus returning from Troy:
Ellis was probably too optimistic about the Tevatron Run II. Those 115 GeV are exactly on the edge of Tevatron's abilities, and the Tevatron people obviously prefer to say that even the 115 GeV Higgs needs years not months, and they can't find it and that the most likely mass is 117 GeV anyway:
The precision measurements combined with the Standard Model indicate a light Higgs, below 200 GeV at 95% confidence level. Note that SUSY wants a light Higgs - MSSM needs a Higgs below 130 GeV. On the other hand, the 115 GeV Higgs may make SUSY kind of necessary:

1. If we believe Dr. Benton and the BBC journalist who convey some of his ideas to us, we know with 91% certainty that there is a Higgs of mass 115GeV. This is an awful lot to say about such an important discovery.

I can think of a number of important consequences such a fact would bear on the standard model. There is no reason for me to be too doubtful, but I think that the confidence level of 91% is a long shot.

It would be a truly breathtaking discovery, beautiful and challenging if true. I am going to try to be open minded: If it's true that's wonderful, and if it's not, it is still a bigger insight than anything we have learned about the standard model in the past 15 years. [Except maybe for the fact that the standard model is a part of string theory. ;)) ]

Best, Michael

2. Hey Michael,

my feelings are very similar to yours. Technically, they always want to claim a discovery if it is a "5 sigma discovery", which is more than 91%. But if he really could argue that the probability of the Higgs at 115 GeV is 91%, then it would definitely change the way how he think about these problems. (And if the SUSY critics studies the links I gave at the end carefully, they would probably start to change their mind.) ;-)

All the best
Lubos

3. They probably want to say that it's not 91% for Higgs - it's 91% for "anything", and they probably want to emphasize that this "anything" can be e.g. nuclear physics proposals by Alejandro Rivero ;-)

http://arxiv.org/abs/hep-ph/0405076

4. :DDD You have a damm'd good memory! My preferred interpretation of figure 5 of the paper, which is all the real meat there, is that somehow a two-doublets-higgs sector gets to be noticed in the spin-orbit contribution to nuclear stability, perhaps some effect in the surface of the nucleus. Of course, as we discussed time ago, the number of degrees of freedom involved do such effect unlikely, so the "nuclear effect" resulting in some systematic error of measurements was other explanation (and, yep, casuality is a third possibility).

Regretly this two-doublets interpretation is not compatible with the 2DHM coming from SUSY, because some of the particles are too low. But at least it is not the "Weinberg SM nightmare"

I like non-standard quest in particle physics, but I wonder if I should curse the day that this one, driving to built figure 5, was struck upon my shoulders. I am no used to so down-to-earth empirical inputs :-)