Comments on: Do particle theorists have a blind spot? http://www.symmetrymagazine.org/breaking/2010/02/14/do-particle-theorists-have-a-blind-spot/ extra dimensions of particle physics Tue, 07 Feb 2012 15:22:30 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: David Harris http://www.symmetrymagazine.org/breaking/2010/02/14/do-particle-theorists-have-a-blind-spot/comment-page-1/#comment-47382 David Harris Wed, 17 Feb 2010 21:50:22 +0000 http://www.symmetrymagazine.org/breaking/?p=6789#comment-47382 Matthew, that comment definitely adds to your argument. It wasn't clear in your talk that the triggering choices were such a significant part of this. It certainly makes sense given that triggering needs to be based on keeping everything that looks close to what we expect plus a little bit more based on what we guess. If we choose the wrong models for new physics, we make the wrong guesses and keep the wrong data. Matthew, that comment definitely adds to your argument. It wasn’t clear in your talk that the triggering choices were such a significant part of this. It certainly makes sense given that triggering needs to be based on keeping everything that looks close to what we expect plus a little bit more based on what we guess. If we choose the wrong models for new physics, we make the wrong guesses and keep the wrong data.

]]> By: Matthew Strassler http://www.symmetrymagazine.org/breaking/2010/02/14/do-particle-theorists-have-a-blind-spot/comment-page-1/#comment-47289 Matthew Strassler Wed, 17 Feb 2010 13:19:34 +0000 http://www.symmetrymagazine.org/breaking/?p=6789#comment-47289 Your suggestion about the "salient aspect... applying if data has ruled out most existing models" is true, but at the LHC it is more serious than that, because of the way data is taken and stored. One cannot assume that the needle can always be teased out of the haystack later when one decides to go back and look for it. At the Tevatron, a lack of foresight (by theorists and experimentalists alike) has literally made many analyses impossible. This is because of triggering (an automated system which must permanently discard all but 1 in a million events real-time) and reconstruction software (in which an automated system interprets -- and potentially misinterprets -- every event before it is stored for later study.) If poor choices are made now in the way data is taken and stored, it becomes almost impossible to go searching for non-minimal physics signals later when people decide those searches are needed. That's why these issues are urgent; we can't afford to repeat the mistakes made at the Tevatron. You and your readers may want to keep your eyes out for a very interesting reanalysis of ALEPH data at LEP, which I am told will appear soon. A small number of researchers got the old software working, and were able to go look into that data for non-minimal phenomena that were only seriously suggested starting in 2004, most strongly by Radovan Dermisek and Jack Gunion. The difficulties these researchers faced were considerable, but manageable. To do the same thing with LHC data will be vastly more challenging. My views are shared by a considerable number of experimentalists, including the researchers on the ALEPH study I just mentioned, and essentially all of the key people now doing non-minimal-physics searches at the Tevatron. In my experience working closely with and consulting for these researchers, I find I usually underestimate the difficulties they face. Your suggestion about the “salient aspect… applying if data has ruled out most existing models” is true, but at the LHC it is more serious than that, because of the way data is taken and stored. One cannot assume that the needle can always be teased out of the haystack later when one decides to go back and look for it. At the Tevatron, a lack of foresight (by theorists and experimentalists alike) has literally made many analyses impossible. This is because of triggering (an automated system which must permanently discard all but 1 in a million events real-time) and reconstruction software (in which an automated system interprets — and potentially misinterprets — every event before it is stored for later study.) If poor choices are made now in the way data is taken and stored, it becomes almost impossible to go searching for non-minimal physics signals later when people decide those searches are needed. That’s why these issues are urgent; we can’t afford to repeat the mistakes made at the Tevatron.

You and your readers may want to keep your eyes out for a very interesting reanalysis of ALEPH data at LEP, which I am told will appear soon. A small number of researchers got the old software working, and were able to go look into that data for non-minimal phenomena that were only seriously suggested starting in 2004, most strongly by Radovan Dermisek and Jack Gunion. The difficulties these researchers faced were considerable, but manageable. To do the same thing with LHC data will be vastly more challenging.

My views are shared by a considerable number of experimentalists, including the researchers on the ALEPH study I just mentioned, and essentially all of the key people now doing non-minimal-physics searches at the Tevatron. In my experience working closely with and consulting for these researchers, I find I usually underestimate the difficulties they face.

]]> By: David Harris http://www.symmetrymagazine.org/breaking/2010/02/14/do-particle-theorists-have-a-blind-spot/comment-page-1/#comment-47240 David Harris Wed, 17 Feb 2010 06:58:22 +0000 http://www.symmetrymagazine.org/breaking/?p=6789#comment-47240 Matthew, thanks for the clarifying comments. I think what you are saying is what I was trying to get at with the last couple of sentences: "Perhaps the most salient aspect of Strassler’s warning would apply if data has ruled out most existing models. It would argue that theorists shouldn’t be too quick to think that what remains is actually a true reflection of reality, unless they have dug much deeper into some of the more complicated models. Only then might they be assured that they are getting closer to painting a true picture of how nature works at its most fundamental level." As I mentioned in the piece, your ideas met with plenty of skepticism but I am not trying to judge one way or the other. I'll leave that to the people doing the physics themselves. I did however think your ideas were valuable and provocative and that is why I wanted to give them a broader airing. Matthew, thanks for the clarifying comments. I think what you are saying is what I was trying to get at with the last couple of sentences:

“Perhaps the most salient aspect of Strassler’s warning would apply if data has ruled out most existing models. It would argue that theorists shouldn’t be too quick to think that what remains is actually a true reflection of reality, unless they have dug much deeper into some of the more complicated models. Only then might they be assured that they are getting closer to painting a true picture of how nature works at its most fundamental level.”

As I mentioned in the piece, your ideas met with plenty of skepticism but I am not trying to judge one way or the other. I’ll leave that to the people doing the physics themselves. I did however think your ideas were valuable and provocative and that is why I wanted to give them a broader airing.

]]> By: Matthew Strassler http://www.symmetrymagazine.org/breaking/2010/02/14/do-particle-theorists-have-a-blind-spot/comment-page-1/#comment-47230 Matthew Strassler Wed, 17 Feb 2010 05:03:20 +0000 http://www.symmetrymagazine.org/breaking/?p=6789#comment-47230 This is an impressive summary of many of the statements in my talk. However, the key point is missing -- and is also missing from the comments from those who were unconvinced. It may be very difficult to consider a wide range of models and signals, but it is necessary. Minimal models give only a fraction of the signatures that the Tevatron and LHC (and other experiments) may encounter. Because of the huge data sets at the LHC experiments, a failure to consider a non-standard signature might easily lead to a failure to discover the associated physics. Our field's future depends on a near-term discovery; if we simply fail to look in a broad-minded fashion, we risk disaster. Fortunately, as current literature makes clear, many of the leading young theorists and experimentalists in the field do not share the opinions of those who were unpersuaded. This is an impressive summary of many of the statements in my talk. However, the key point is missing — and is also missing from the comments from those who were unconvinced. It may be very difficult to consider a wide range of models and signals, but it is necessary. Minimal models give only a fraction of the signatures that the Tevatron and LHC (and other experiments) may encounter. Because of the huge data sets at the LHC experiments, a failure to consider a non-standard signature might easily lead to a failure to discover the associated physics. Our field’s future depends on a near-term discovery; if we simply fail to look in a broad-minded fashion, we risk disaster. Fortunately, as current literature makes clear, many of the leading young theorists and experimentalists in the field do not share the opinions of those who were unpersuaded.

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