I am pleased to report that the book I wrote on the CDF experiment and on collider physics at the Tevatron, "Anomaly!", has been declared this week's "book of the week" by the Times Higher Education site. There, you will be able to read Tara Shears' very nice review of my book, along with some additional considerations and biographical notes on yours truly by Karen Shook.
It is nice for me to see the product of eight years of work being appreciated. So far I am only aware of very positive comments on the book, from the endorsements by Witten, Kane, Carroll and others (you can read them at the World Scientific site of the book), to a great review by Peter Woit in his blog, to this one now. I believe a few other reviews are coming soon, and I would actually be curious to see at least one by some fastidious reviewer who pointed out the mistakes I made (I am sure I must have made a few, although I am not aware of any yet!).

Since Tara in her review writes in some detail of the "Superjet affair", which is described in chapters 11 and 12 of the book, I think it is a good idea to offer below a clip from that story, for those of you who went as far as reading the THE review and got a bit curious about it, but not enough to buy the darn thing. 

The clip describes a discussion between me and Avi Yagil which occurred the day before an important meeting where the CDF collaboration discussed the destiny of the analysis of what had been called "superjet" events - events containing the signal of a leptonic W boson decay associated with two or three hadronic jets, one of which was energetic, and b-tagged by both a secondary vertex identification algorithm (SECVTX) and by containing a lepton - which turned out to be itself quite energetic, at odds with standard model predictions. 13 such events had been found, when 4 were expected by known sources; in addition to being in excess, the kinematical properties of those events made them a very odd observation. Have fun with the clip - and, if you then decide to buy the book, you may get to the amazon site at this link.

(I have added a few clarifying statements here and there in the text below, within square brackets).


Avi Yagil's office in the CDF trailers was only two doors away from mine. Avi used to arrive at eleven in the morning and leave at twelve for lunch; then sometimes he would be back for a couple of hours in the afternoon. I knew his office schedule well because I had learnt to distinguish his pace every time he walked the long corridor behind my back. He had a peculiar way of walking, one which he had probably acquired during his military service in Israel. It produced more noise on the carpeted floor of the portakamps than you would think possible. His habit of speaking with a loud voice and his friendliness with most of the people he met in the trailers also helped tagging him as he approached. I had come to know very well what Avi thought about the Frascati analyses: his opposition to the revised top cross section measurement had been fierce. I liked to prod him when the chance arose, however, as his opinion was always interesting to hear. Avi, on the other hand, knew that as member of the Oversight godparent committee I was supporting Giromini's request of a quick publication of the results [of the superjet analysis]; but he also seemed to have a good opinion of me as a physicist.

I stopped him in front of my office on a beautiful June morning, the day before the special meeting, as he arrived fresh as a rose. 

"Hi Avi, have you got a minute?" I asked him.
"Sure, baby. What do you need?" He was well-dressed as usual, a sports T-shirt carefully tucked under the freshly-ironed trousers, mocassini on his feet, no socks.

"Well, I would love to hear your opinion on the issues that will be discussed tomorrow. Come in, take a chair."

Avi stepped in my office, but he did not sit down. "You know my opinion. I'm telling you, that's serious junk. Those guys are monkeys! Monkeys dealing with heavy machinery. Very dangerous." he explained, waving his hands.

"Come on, Avi. What's the heavy machinery?" I inquired.

"Claudio and I worked for years to understand soft lepton tagging [the algorithm identifying b-quark-originated jets by flagging the presence of a muon or electron in a jet]. We put together an algorithm that is not for everybody to tamper with. You know all this stuff. SLT works wonders, I'm telling you, but you have to know what you are dealing with. In the beginning we sat together and I gave Paolo all the instructions on how to use the SLT. But they do not really have a clue. You put artillery in the hands of monkeys, then you tell me what you get."

"You can't be serious." I replied. "If you had a complaint on the way they estimate backgrounds in the SLT-tagged W+jets sample you should have told us months ago! I think you were explicitly involved in the review process at some point." 

"No, no, the estimates are good, Tipton's committee has checked them ok [Paul Tipton was the chair of the review committee which scrutinized Giromini's top quark cross section measurement]. But all this issue with the scale factor is totally fucked up. Who needs another scale factor!" 

"But I bet you've heard about the result of Paolo about the origins of the difference from unity of the scale factor," I tried to argue. "Inserting a new decay table in the Monte Carlo, the other studies on the data, finding secondaries from nuclear interactions in the silicon…" [The scale factor is the ratio between the efficiency with which a b-quark jet is identified as such by the SECVTX algorithm in simulated and real data; it should be equal to 1 if the simulation is good].

Secondary particles are created when an energetic hadron hits a nucleus of the detector material. An incorrect modelling of the rate of such nuclear interactions may affect the estimate of spurious SECVTX b-tags, because secondary tracks have a broader distribution in the impact parameter distribution, which causes them to produce secondary vertices not due to the decay of heavy-flavor particles. I continued: "They showed they can explain away a good part of the discrepancy from unity of the scale factor. Don't you believe that the cross section for top production is lower than what we have published?"

Avi was adamant: "Listen, I don't give a shit about the top cross section. The issue is another one here. They want to prove they have found some new physics in W+jets data, and they need the scale factor higher than one to make their case stronger." That was of course true: if you observe an excess of events and you can explain away fewer of them as being due to top production, you are left with a bigger, more significant effect.

"But we are scientists," I argued. "We have to revise our measurement if we think we have a better number. Let's keep the two things separated. I think we should let Paolo publish the new top cross section. Then take stock, and see how things stand..."

Avi interrupted me. "I don't want another top cross section out. We have to stop this circus. It's not a matter of scientific integrity."

"But do you really think the scale factor is one?" I inquired.

"No, it's probably ok. It's 1.2, whatever. That is not the question!" was Avi's reply. 

"Then let's let it out, why not?" I argued.

"It's not going to happen. They have to be stopped somewhere."

Seeing that Avi was stubborn on that issue I changed topic. "Look, I have checked the Kolmogorov tests of Giromini. They are okay. What do you think of the kinematics of those events, then?" I asked. [The Kolmogorov test checks the conformity of two distributions. It was used in the superjet analysis to show that the kinematics of the superjet events were at odds with standard model predictions].

"Baby, those events have been around for years. Come on! We have known since 1994 that we had some funny events there. Three years ago they tried to sell us that they'd found the Higgs with 10 odd events in the 2-jet bin. Then they changed their minds, and it was charm plus missing energy in 50 SLT tags. And now they've settled on 13 multiple tags."

It was hard to deny that Avi had a point there. Over the previous few years the Frascati group had produced three different claims. All of them were centered on subsets of data produced by applying slightly different selections to that same sample of W+jets events. While I was seeing that sequence of studies from the positive side - a continuing investigation of the data and a search for possible explanations, after something odd had been spotted - Avi perceived it as a proof of un-scientific behavior, and a threat to the reputation of the experiment. In CDF he was not the only one who felt that way.

I conceded it. "Ok, ok. I do not deny that. Still, I believe those events are weird enough that they should be published. What do we lose? Imagine if a bright theorist comes up with some new model and..."

He interrupted me again. "No way, baby. CDF will not publish those events. I am going to see that this does not happen."

"Ok Avi, then I guess we'll have fun tomorrow..."

"Yeah. You bet. See you, buddy."

Yagil had been sincere: he did not have anything concrete to object to, with the exception of the scientific method allegedly used by Giromini; but that alone made all the difference to him. His was a good representation of the feelings of the American lobby in the Top group. In addition, they could not accept that the result they had recently published would be revised by Frascati, and they found it equally unacceptable that Giromini would win his battle with the superjets. It was for sure going to be an interesting meeting!