You probably have seen the latest announcements from Dennis Kovar (DOE) about stopping BaBar and all work on Nova and the ILC. See Alexey Petrov’s post, Tommaso Dorigo’s post and Gordon Watt’s post for some details and commentary.

If, however, you go to the DOE web site, you will find a happy announcement of President Bush’s visionary plan Twenty in Ten calling for a mandatory renewable fuel standard and new CAFE standards. Here’s the picture:

There is absolutely no trace that anything is wrong with the budget, or that sacrifices in basic science will now be made for the sake of other national priorities… (and I’ll keep my thoughts about that private, though I am sympathetic to Bee’s post from the beginning of the year.)

You might think that energy.gov is simply the wrong place to look - one should check the Office of Science web site to find out about the impact of these budget cuts, and how the DOE / Office of Science plan to adapt to the new reality. But there again, there is not a single byte of information about the new budget. In fact, the central image is the front page of a “landmark publication” called Facilities for the Future of Science: a Twenty-Year Outlook (Nov, 2003). They should certainly take that down!

If you go to the DOE Press Release page, you will not find any information or announcements about the budget, though there is a call for nominations to the Enrico Fermi Prize. And the HEP page also contains no information.

Of course I do not expect to see dramatic announcements full of woe and gnashing of teeth, but I do expect official statements, full of facts and not p.r., for the benefit of people in the field and for the interested public (including the news media). Aren’t web sites like those intended for the responsible dissemination of information? That is, after all, why we invented the internet…

No, the additional commentary is not from me - it is quite good! If you find this topic interesting, then you should read the post Scientific Bang for the Buck, by Tommaso Dorigo, and comments to that post. Also, there is an intriguing discussion on the Deep Thoughts and Silliness blog, called “A physicist stumbles into a statistical field.”

It strikes me that using theoretical priors to evaluate the importance of a discovery is, to a certain extent, putting the cart before the horse. Canonically, we would like to collect data impartially, and then confront our hypotheses with those data. Ideally, we would place all hypotheses on an equal footing (which is one reason why null-hypothesis tests are bad), and let the data tell us which ones to discard.

We all know that HEP does not work that way, not quite. First, there are so many facts that we need to agglomerate them in some quantitative way. The chi-squared or likelihood tests based on precision electroweak measurements (see the “blue-band” plot below) or the constraints on the unitary matrix from key measurements in the flavor sector are good examples of this. Furthermore, our hypotheses are really models and theories, some more speculative, some less, which are already based on a chain of reasoning and experimental results, and rarely can be rejected with just a few more data. (There are exceptions, though - the non-observation of a SM-like Higgs boson with a mass below 150 GeV would be very bad for minimal low-energy supersymmetry.) So there is a huge difference between overthrowing the standard model, and ruling out the theory of universal extra dimensions (attractive though it may be). We expect one to (continue to) succeed, and the other we hope to succeed, but expect to fail. As a community, we have our “priors” as to which theory is more likely to be correct.

To take the step of constructing a function which represents these priors and using it to place numbers on discoveries, or potential discoveries, goes well beyond common practice or thinking. It seems to me like an unwanted and perhaps dangerous feed-back loop. It supposes that we can quantify the very things that we can’t anticipate by the level at which we can’t anticipate them. Since this is clearly impossible, we should substitute deviation from our priors for how successfully an experiment guides us to a better understanding. Aside from overlooking the role played by measurement, this approach would not have helped us to overcome the quagmire of the Bootstrap Model (a.k.a. particle democracy) or to move from Regge Theory to quantum field theory, and ultimately, to QCD.

I do believe strongly in searching for new physics (deviations from the standard model) in a way that is broad and unfettered by theoretical prejudice, so I am sympathetic to many of Bruce’s ideas. But I don’ think we can quantify our potential results in the manner he has suggested.

I was happy to see that Evolving Thoughts picked up the discussion of judging experiments based on concepts taken from information theory. Apparently these ideas are not new and show the fault lines between the statistics community and certain scientific groups, including HEP.

Today I would like to iterate an earlier point: what is the value of measurement? (in the context of judging experiments)

The use of “surprisals” and the like limit the scope to discoveries only, with the idea that more surprising discoveries are worth more than “ordinary” discoveries. (One goes on from there to develop the notion that an experiment, or analysis, which is better directed toward making a surprising discoveries is inherently worth more than one which makes “expected” discoveries - the problems in this formulation seem pretty clear when stated this way…) But this overlooks completely one of the main roles of experiment, which is to measure. We know that the standard model is successful not only because someone discovered the W and the Z bosons, the top quark, etc., but also because a host of precision measurements when taken together conform to the expectations of the standard model. No one would argue that experimental (or theoretical) particle physics would be just fine without this corpus of measurements, and I doubt that many people would say that looking for new physics beyond the standard model doesn’t need concrete and precise knowledge of standard model particle properties and interactions. After all, we know in which range the mass of the standard model Higgs boson must lie, and some people are enthusiastic about supersymmetry because of the way it conforms to measurements of precision electroweak observables. What situation would we be in today if we lacked those measurements, or they were considered unimportant? (Another example might be the current empirical knowledge of CP violation, culminating in the beautiful sets constraints on the CKM matrix and the unitarity triangle, but I am more familiar with electroweak physics, myself.)

(The top quark mass plot comes from the Tevatron Electroweak Working Group, and the “blue-band” Higgs mass plot comes from the LEP Electroweak working group.)

Of course I hope for a surprising discovery from the LHC or Tevatron data, one which is not foreseen by theorists. And I would be happy for clear signs of new physics even if it corresponds to one of the many available excellent theoretical ideas. But if people like the idea of judging experiments in some semi-quantitative way, how might one incorporate the value of measurement? Any ideas?

Charm etc. posted an interesting discussion on Information Entropy and Experiments. The bloggers describe an attempt to evaluate the worth of experiments on a statistical basis, comparing the results they produce against a priori expectations from theory. (See arXiv:0712.3572 from Bruce Knuteson.) They point out very perceptively that this procedure relies too much, if not entirely, on those expectations from theory. One might wonder where else we should get our expectations, but this is not the point - the most important discoveries are the ones for which there was no expectation. And after the discovery was made, theory was altered radically, therefore changing the priors. See Charm etc. for a succinct discussion.

I think there is another problem with the approach. How does one evaluate the accumulated value of crucial measurements of particle properties and interactions? How much does a factor two improvement in the W mass measurement increase the value of a Tevatron experiment? What about the Bs oscillation frequency? These measurements fit in the standard model - in fact, they are important if not crucial empirical inputs to model calculations, without which one could not move beyond the standard model. I don’t see how to set a value for such information in the sense of theoretical expectations; if we discard the standard model in the next ten years, and replace it with something much better, is the value of the W mass measurement diminished or enhanced? At what point does the W mass (for example) become mundane or less than crucial, in contrast to the present time? I suppose there will be a day when the W mass can be predicted sufficiently well, or when it ceases to provide any insights into new physics, and these developments might be reflected in the nature of the theoretical priors required by this evaluation of scientific merit, but I doubt this could be made clear or concrete.

The bloggers at Charm etc. are also skeptical of this approach, interesting though it may be to talk or blog about it. But if someone takes it more seriously, then perhaps the next question would be: how do you place a quantitative value on individual, and improving, measurements, taking into account the possibility that some measurements are wrong?

Update: (5-Jan-2007) There are nice discussions of this issue at Quantum Diaries Survivor and Deep Thoughts and Silliness.

Several bloggers have detailed the budget disaster of December 2007 (for example, Joanne Hewett, Peter Woit and Andrey Petrov), so I will not try to do the same. Furthermore, it is tempting to declaim the demise of science in the United States, or to fret about the future of Fermilab. I don’t think I would improve anything or anyone by doing so.

Instead, let me try to make the following point: More than ever, the success of the LHC program is crucial. Exciting and profound discoveries, if they do come, must be carried out with the utmost professionalism and care. We cannot afford to bungle any highly visible analysis, nor can we mire ourselves in excessive regulations and procedures for approval of new results. Senior physicists need to be engaged in the stuff of physics, not only in managing cadres of people. Young people may not have the experience to avoid naive mistakes; they should be educated and trained as well encouraged to be innovative and iconoclastic. Only Nature can determine the sources of new physics at the LHC, and only we experimenters can raise the quality and depth of our work to levels never seen before. This may be the last chance to show the world that high-energy physics is worthwhile…

(A.A.Michelson, and M.Faraday)

Slowly I am managing to return to the land of physics blogging, and much of what I see now is great!

One item which strikes me is a post written in Charm, etc. in which the author describes how a very nice 5-sigma pentaquark signal came and went! This may well serve as a cautionary tale for all of us at high-energy colliding beam experiments. If this peak had been the Higgs boson, the collaboration(s) might have been delighted to announce discovery. (Some would argue that the original W boson and top quark discoveries were on shakier ground, statistically speaking.)

I think it is great that the CLAS Collaboration wrote a article demonstrating the results from their first set of data, and the second, which is fives times larger than the first. This plot sums up the situation:

The points represent the first data sample, on the basis of which a 5-sigma significance was claimed. The solid line represents the second data sample, which is more than five times larger than the first, which contradicts that claim. Both data samples were taken with the same apparatus under the same conditions, by the same people. The collaboration wrote a paper exploring the statistical issues involved (see arXiv:0709.3154). See the clear and concise article for details, or or Charm’s original peak-finding post.

I must tip my hat to Tommaso, who has made several excellent HEP-related posts in the past several days. In particular, he has tipped us off to some interesting physics from the Tevatron.

First, he described with wonderful clarity and simplicity the analysis of the angular decay distributions of the X(3872). This is a very nice result coming from CDF which helps identify the nature of this peculiar object. See his post for the discussion, to which I would add that this kind of physics is rich and interesting, if not the most popular in HEP. However, if you want really to know what’s going on, you need to pay attention - if new particles are found at the LHC then the same kinds of analyses will be needed to identify them. Also, I agree that it is slightly embarassing that CDF had a nice signal in the data but did not spot this until after Belle did. We are not being vigilant enough, perhaps…

Second, Tommaso predicts that evidence for single-top production will be found by CDF and D0 this year. He is probably right, and for the reasons why this is a difficult experimental task, see his posting. This topic has been on the main menu of the Tevatron program since the beginning of Run II, so it will be nice to check that one off, as we have already done for di-boson production. And as more data are accumulated, this provides another opportunity to probe for new physics, either in the properties of the signal events, or in related samples. Is there a reason why one might see a top-bottom resonance - certainly possible. Could anomalous events fall into this SM sample? Let’s hope so, and that someone looks.

Finally, Tommaso discussed the famous Mtop-MW plot which shows that the measurements are more comfortable with the MSSM than with the SM, though they do not rule out the SM (as Tommaso stresses). Here I see things a little differently than Tommaso does, so I will have to prepare my own comments on what this plot means and what the future may bring. On one thing I strong agree and would emphasize: the precise measurement of the top-quark mass must remain a high priority for the Tevatron program. Not only does it help give a hint of what is to come at the LHC, but for experimental reasons the Tevatron experiments really can measure this better than the LHC ones, at least for the next several years. I hope very much we will achieve 1.0 GeV, which can be compared to the projection of 1.5 GeV at the LHC…

One of my favorite quotes comes from Louis Pasteur:

"In the fields of observation, chance favors the prepared mind."

It seems to me that too much of our research is guided by our theoretical prejudices, and there is too little emphasis on pursuing the oddity that crops up in our data. It takes a different kind of skill and discipline to do so, but I believe that such pursuits are vitally important in experimental science. Of course the vast majority of oddities are just statistical fluctuations or systematic effects (in which case a proper investigation may save us from publishing a wrong result!) but if an anomaly turns out to be real, then science will get a huge boost forward.

Two recent posts speak to this topic. The first one comes from Jao Ortega-Ruiz at his blog physics musings. He gives a wonderful account of several crucial observations made in the last century - I strongly recommend reading it! (It is interesting to note that he is a theoretical physicist.)

The second comes from Tommaso Dorigo's prodigious blog A Quantum Diaries Survivor. He talks about fishing for new physics, and with a cute diagram shown by Jaco Konigsberg, makes the argument that we should be "fishing" in our data if we hope to find something "deep."

I think that every advanced graduate student and post-doc should be spending at least 20% of his or her time chasing something that looks wierd to him or her. You learn the most that way and your research becomes your own - not just part of some grand program to "do collider physics." It is so much more interesting to go to an internal physics meeting and hear about a problem that has cropped up in someone's analysis than to listen to answers to a dozen questions posed by experts trying to raise the level of a given analysis. In my opinion, the latter can be carried out offline, while the former, potentially, enriches all who are present and who participate in the discussion.

Please read a very eloquent piece by Lawrence Krauss called Discovery for the Sake of Discovery. It is published in SEED magazine as part of a series on the LHC. Krauss makes a most basic and fundamental justification for high-energy physics experiments - they are an important example of what is good about our civilization. For me, this is the real reason why we should do particle physics, both on the experimenal and the theoretical side.

But don't waste time reading my comment - read his article please!