The CMS collaboration at the LHC collider has just produced its very first results on the production of Upsilon particles, with 280 inverse nanobarns of proton-proton collisions at 7 TeV center-of-mass energy. I wish to discuss these results here, to explain what is interesting in these very early measurements, and what we can expect to learn in the future from them.
The production of resonances decaying to muon pairs is one of the first things one wants to study when a hadron collider starts operation. This is because these particles are extremely well known, so one immediately figures out whether the detector is working properly, what is the resolution on the momenta of the reconstructed particles, etcetera.
I am preparing a disclaimer to be added to the bottom of my posts here. The problem I am trying to solve -at least in part- is that the colleagues in the scientific collaborations I work for apparently fear that I be identified, by science reporters or other media agents, as an official source of information from those experiments.
The Atlas collaboration made public, just in time for the 2010 ICHEP conference in Paris, the projected reach of their searches for standard model Higgs bosons. This is a whole set of interesting new results which, although necessarily still based on simulations, tell us a lot about what we might see toward the end of next year at the LHC.
Here I will just flash a couple of the results, because the plentiful online documentation that ATLAS provided makes it a worthless exercise on my part to just echo it here. However, maybe I can comment the most relevant plots for those of you too lazy to browse the information-thick ATLAS pages.
So, now we know. There is no 3-sigma signal from the Tevatron.... Sure, because they have not combined their MSSM searches yet!
I will spend little time here discussing the various colourful ways by means of which I have been depicted:
- unreliable source of information
- fame-seeking blogger
- Paris Hilton of Physics
- Less trustworthy than Paul the Octopus
- and I could go on, but I prefer to leave these envious utterings where they first diffused their stench.
I am amused by the attention, but rather disappointed by the utter failure of all these commentators to understand what went wrong here: the press jumped at this gossip, without a blink, where there simply was no story !
Prayer to the Funding Agency Reviewer
(dedicated to those who worry about the detrimental effect of rumours)
Oh Funding Reviewer, on whose hands
Rests the destiny of full many an experiment:
Be true to yourself, and bias not
Thy sober judgement through the browsing
Of tricky sites or malicious magazines.
You were chosen, wise among the wise,
To distribute thy moneys to the worthy.
Human knowledge is at the stake:
Neglect the rumours, and listen not
To lesser souls. Let the Science be your guide.
Funny. While dozens of online media are abuzz with the (non)-news, and while Fermilab Today tweets
that there is no Higgs in store for us and a blogger in search of fame is just spreading unconfirmed voices which have no foundation, Lubos Motl over at the Reference Frame gets more detailed rumors on the same thing
, and that does make things a bit more interesting.
The CDF experiment has just released their new average of top quark mass measurements, obtained with analyses that use up to 5.6 inverse femtobarns of proton-antiproton collisions provided by the 2-TeV Tevatron collider: the new measurement is M(top) = 173.1 +- 0.7 (stat) +- 0.9 (syst) GeV
, a measurement with a total uncertainty of 1.3 GeV, or 0.75%!
Have a look at the various measurements that enter the calculation in the graph below.
Think a a mere 0.0350 millionth of a millionth of a millimeter is unimportant? Think again.
At the Paul Scherrer Institute in Switzerland, an international team of researchers has now measured the proton with experiments they say are ten times more accurate than all previous ones. And all the old values for the dimension of the proton, the nucleus of the hydrogen atom, are off. Instead of 0.8768 femtometres it measures only 0.8418 femtometres, they say
If so, at least one fundamental constant now changes and physicists also have to check the calculations of quantum electrodynamics. This theory is assumed to be very well proven, but its predictions do not agree with these latest measurements.
Sometimes my sympathy for science magazines (in print and online), which try to keep intelligent readers informed on the progress in basic science, gets dampened by observing how they end up providing a narrow-sighted look at things. What is at stake is usually not science popularization: an article you read does not need to inform you of all what is going on in a field of research; rather, it is the correct acknowledgement of the different efforts. It sometimes happens that a group works hard on something, they believe they have made great progress and furthered everybody's knowledge in the field, and then an article appears that discusses somebody else's contribution, which came later, was less successful, and less valuable.
if you came here to learn more details about the rumored Higgs signal, which media around the world are discussing and which Fermilab Today just dismiss-tweeted, please visit this other more recent post
for more details. Below is the original post which apparently originated a lot of buzz.
And for once, I feel totally free to speculate without the fear of being crucified. If you have followed my past blog adventures for long enough, you know that in at least a couple of occasions my posts have created some friction.