## Monday, February 27, 2006 ... //

### Keith Baker: TRT at ATLAS

I just returned from a colloquium about the LHC. Keith Baker from Hampton seems to be a very good speaker and he gave a convincing and inspiring talk. A bigger one half of the talk was about experimental high-energy physics - with some elementary introduction about the energy scales of the Universe - and a smaller one half was about the black physicists and related policy issues. The speaker was an African American himself.

The LHC will be completed in 2007. There are two major detectors: the CMS on the French side and ATLAS on the Swiss side. Baker and his collaborators work for ATLAS, much like some people from Harvard and many other places.

While Harvard is focusing on the muons, among other things, Hampton University's main interest is TRT which stands for transition radiation tracking. (In fact, TRT seems to be the "most American" segment of the LHC.) When charged particles move from one environment to another, they emit transition radiation and its detection is a useful tool to identify the particles and figure out other things, too. Baker described how well can they distinguish electrons from pions or how they attack the question of the angular distribution and others.

He also showed some maps and graphs of the grid. Hampton has 5 computers in it which is less than the BU+Harvard group but these five computers are run primarily by students and they are important for other reasons discussed below.

His main motivation was to confirm or falsify the Randall-Sundrum models of a warped extra dimension - and they can essentially complete this job within a year or so after the LHC starts, assuming a certain upper bound for the "amount of fine-tuning" in the RS theories. If you draw the parameter space of these models, a part of it is already excluded by experiments that have been done. Then there is a "fuzzy" boundary on the right side of the diagram imposed by the assumption of the absence of fine-tuning, and the precise nature and justification of this boundary was the topic of some debates.

What you actually want to detect in these models are the narrow resonances describing the excited warped KK modes of the graviton. A quark-antiquark pair annihilates into the excited graviton which subsequently decays into a lepton-antilepton pair. The main background is, of course, the same process with gluon as the intermediate state, and some extra work is needed to distinguish them from each other.

One question was about the coupling constant of the SM particles to this excited graviton mode, and I am not sure whether the answer was quite correct. I don't think that the rest mass influences the coupling of very high-energy leptons to the excited gravitons. Our phenomenology students quite certainly know the right answer but they did not intervene in this discussion.

Black colleges

Another important part of the colloquium was devoted to the role of the historically black colleges and universities (HBCUs) in particle physics. There are roughly 100 colleges, mostly in the Southeast of the U.S., that were created to educate the former slaves after slavery was abolished. (The oldest HBCU was founded in 1837, however.) Hampton University is the only one that has a PhD program and Baker's talk has shown that they are doing quite a serious and meaningful stuff. At Hampton, an unusually large portion of the work is done by students.

There were some funny moments - for example, when he was showing how good different teams working for ATLAS are, Hampton University was almost the best one in one aspect except that some Russians turned out to be ahead. Still good.

Despite being open-minded about the best arrangement, Baker has made a pretty good case for the HBCUs - someone may call it a case for "segregation". Unlike most of the far left-wing whackos, he seems to appreciate many aspects of reality. He discussed what thoughts the black students actually have when they decide where to go. They want a place with many potential partners (I mean girls and boys), and as far as physics is concerned, those who can make it often prefer the "majority" universities.

Baker says that the average students work on whatever they are asked to work on as long as they are paid. The best students want to work on cutting-edge problems, and if Hampton University is not able to show them that they will have a better environment than their colleagues at Harvard or elsewhere, then Hampton will rightfully lose these students, he said.

Also, and this counts as an advantage for HBCUs, the good students want to feel that they are as special and excellent as the good majority students do, and this goal may be easier to achieve with this "segregation". Some of Baker's arguments about educating the black elite were similar to those of La Griffe du Lion who praised the basic principles of the Meyerhoff scholarships which were very successful at least back in 2000.

Another simple reason why HBCUs are important is that a rather large majority of degrees awarded to the blacks comes from these schools.