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Multi-muon news January 26, 2009

Posted by dorigo in news, personal, physics, science.
Tags: , , , ,

This post is not it but no, I have not given up on my promise to complete my series on the anomalous multi-muon signal found by CDF in its Run II data. In fact, I expect to be able to post once more on the topic this week. There, I hope I will be able to discuss the kinematic characteristics of multi-lepton jets. [I am lazy today, so I will refrain from adding links to past discussions of the topic here: if you need references on the topic, just click on the tag cloud on the right column, where it says “anomalous muons“!]

In the meantime, I am happy to report that I have just started working at the same analysis for the CMS experiment! In Padova we have recently put together a group of six -one professor, three researchers, a PhD student, and a undergrad- and we will pursue the investigation of the same signature seen by CDF.  And today, together with Luca, our new brilliant PhD student, I started looking at the reconstruction of neutral kaon decays K^\circ \to \pi^+ \pi^-, a clean source of well-identified pion tracks with which we hope to be able to study muon mis-identification in CMS.

Meanwhile, the six-strong group in Padova is already expanding. Last Wednesday professor Fotios Ptochos, a longtime colleague in CDF, a good friend, and crucially one of the authors of the multi-muon analysis, came to Padova and presented a two-hour-long seminar on the CDF signal in front of a very interested group of forty physicists spanning four generations -from Milla Baldo Ceolin to our youngest undergraduates. The seminar was enlightening and I was very happy with the result of a week spent organizing the whole thing! (I will have to ask Fotios if I can make the slides of his talk available here….)

Fotios, a professor at the University of Cyprus, is a member of CMS, and a true expert of measurements in the B-physics sector at hadron machines. We plan to work together to repeat the controversial CDF analysis with the first data that CMS will collect -hopefully later this year.

The idea of repeating the CDF analysis in CMS is obvious. Both CDF and D0 can say something on the signal in a reasonable time scale, but whatever the outcome, the matter will only be settled by the LHC experiments. Imagine, for instance, that in a few months D0 publishes an analysis which disproves the CDF signal. Will we then conclude that CDF has completely screwed up its measurement ? We will probably have quite a clue in that case, but we will need to remain possibilistic until at least a third, possibly more precise, measurement is performed by an independent experiment.That measurement is surely going to be worth a useful publication.

And now imagine, on the contrary, that the CDF signal is real…


1. Andrea Giammanco - January 26, 2009

> a group of six -one professor, three researchers, a PhD student, and a undergrad

This reminds me of this quote:

“When we jumped into Sicily, the units became separated, and I couldn’t find anyone. Eventually I stumbled across two colonels, a major, three captains, two lieutenants, and one rifleman, and we secured the bridge. Never in the history of war have so few been led by so many.” (General James Gavin)

2. Kea - January 27, 2009

So has your estimate for the reality of new physics gone up, down or remained the same?

3. Daniel de França MTd2 - January 27, 2009

Tommaso will share the data so that we can fit the function!

4. Amos - January 27, 2009

Its getting to almost be time we heard from D0, no?

5. dorigo - January 27, 2009

Hi Andrea,

yeah, I know that one, and indeed it does fit. It is unfortunately not an exception -HEP is growing old!

Hi Kea,
no change – I still think it is a background. However, I have realized that this anomaly will stay with us for a while, until LHC kills it. So I told myself, I should be joining the slaughter…

Daniel, which function, the Z lineshape ? Well, if that’s what you refer to, it is a set of 24 root histograms. If you know how to use root, or even if you don’t but are willing to fiddle with a few commands, I can provide the file. Email me.

Amos, I do not think so.
D0 has not published B-physics results in some time now. They not only are heavily undermanned, and concentrating on the few important analyses which justify the experiment’s existence (Higgs searches, top mass, exotics signals), but they have never measured the bb cross section, nor did they measure the integrated b-mixing parameter. I think it will take them quite some time to produce a detailed result. If they attempt a quick-and-dirty study, instead, I think it will not add a lot of knowledge. But I might be pleasantly proven wrong.


6. Luboš Motl - January 27, 2009

It’s not really my business but I personally consider the “personal union” between different teams at different accelerators unfortunate because it will give the statements the character of an “independent verification” even though it is not.

Sorry to say but the gigantically cross-sectioned anomalous processes you report are almost certainly a result of a sloppy theoretical analysis, which is independent of the detectors and colliders, so it is likely that you will repeat the sloppy analysis again and produce a seemingly independent, but not really, confirmation.

7. Daniel de França MTd2 - January 27, 2009

Well, Tommaso, I was kinda joking with that other posting about the fitting… Like, you sharing the results of CDF for us so that we could play “fitting the function”… But I guess I will send you an email later, then.

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