A Quantum Diaries Survivor

It is by now public that Rolf Heuer, the Director General of CERN, in announcing for December 13th two back-to-back talks of the CMS and ATLAS experiments on their Higgs search results with 2011 data, warned that the results might not be conclusive yet. Besides, nobody really could expect them to be, since the sensitivity expected by both ATLAS and CMS in the still not excluded region of the Higgs mass, with 5/fb of data per experiment and 7 TeV running conditions, ranges from 2 to 4 standard deviations in the rosiest circumstances.

The text below was graciously written for this blog by Alejandro Rivero (below),  a friend who has contributed to this blog other times in the past. His theoretical ideas are off the mainstream, but in a way which makes them interesting to me. I hope some of you will appreciate reading about the whole thing in summary here - Alejandro has a few papers out which you may want to read if you are specifically interested in the matter.

Update: I am keeping out of this, but you may well be interested in reading what Gibbs, Woit, and Motl have to say about recent leaks on the ATLAS and CMS results. So I hope I won't be crucified for three general links now!Update 2: And it is now public that a seminar at CERN will be given by ATLAS and CMS on December 13th. So the wait is almost over, officially...I have not written in a while - a full week. This is uncharacteristic enough that I owe you some sort of explanation.

Do you remember the multi-muon anomaly in CDF ? The matter was discussed with quite some detail in a series of posts in this blog (back then at wordpress). In a nutshell, CDF could not explain their sample of events containing two muons, when these particles had a very large impact parameter (the impact parameter is the minimum distance of a trajectory from the interaction point: a large value indicates that the particle was produced elsewhere).

For you today here is a test of whether you shoud trust your intuition when confronted with an apparently simple problem. Incidentally, this article is the answer to the "Guess The Plot" riddle I posted a few days ago here.Suppose you are given two measurements of the same physical quantity. Make it something easy to visualize, such as the length of a stick. They tell you that when measured with method 1 the result was x1=10 cm, with a estimated uncertainty s1=0.1 cm, and when measured with method 2 the result was x2=11 cm, with estimated uncertainty s2=0.5cm. Here is a question for you today: What is your best guess of the length of the stick ?

Totally overshadowed by the news of the new Opera measurement of neutrino speeds, yesterday CERN officially released the combined result of ATLAS and CMS searches for the Higgs boson. The news has been given already in two prominent particle physics blogs (Resonaances and Not Even Wrong), so I think I am not obliged to do anything more than point you to those, who cover the matter quite accurately.

After a more careful reading of the paper, the listening to a seminar on the result, and some discussions, I can share with you a few more details on the Opera measurement.

UPDATE: some technical considerations on the measurement are available in a followup post I wrote after attending a seminar on the new result today. In particular, one startling consideration emerges - if the reading of the 20 MHz Opera clock were off by just one tick, the result would be compatible with v=c. UPDATE: you can download the new Opera paper at this link. You will need to use the username and password "neuvel".

It's been a while since my last "guess the plot" posting. The simple explanation is that I did not happen to run into any fancy graph in the last month or so. Now, today I have one for you to guess, but I must add that I believe it is rather easy to understand what it represents. Less obvious is to completely understand the math behind it, and the implications of the construction.

Today I wish to briefly discuss a recent important measurement produced by the LHCb collaboration, a measurement of CP violation in the decay of charmed mesons. Before I do, I think I need to explain some details of the LHCb experimental arrangement, because it is different from what most readers here are familiar with.And, update: rather than putting it at the end, I prefer to link Resonaances' post on the same subject here this time - he wrote about the matter yesterday and did a much better job than I do below. Sorry for noticing it after posting mine!Some pedestrian kinematics

These days I am preparing a three-hour course of statistics for particle physicists which I will give at a winter school in a couple of months. This stimulating task forces me to find nice and simple examples of good and bad applications of basic statistics. Stuff with high didactical value, and hopefully also entertaining.

The Arxiv today features a quick-and-dirty study of the occurrence of electron-positron pair signal in the NOMAD detector, which obtains very strong bounds on the superluminal behaviour of energetic muon neutrinos like the ones whose speed has been recently and famously measured by OPERA.