Two days off June 30, 2006
Posted by dorigo in news, personal.add a comment
I am taking two days off… At the beach with my family.
Will be back in blogging mood on Sunday.
Abstract for QCHS 2006 June 29, 2006
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Today I sumbitted an abstract for my presentation at “Quark Confinement and the Hadron Spectrum VII” (http://qchs7.ist.utl.pt/) which will be held at the Azores in September.
Here is what I came up with… Not very original, but what matters is the content of the talk, not the abstract. There will be new results aplenty to show for both CDF and D0, and I will have to pick the most interesting and intriguing ones - I think I will have fun.
Precision Standard Model Measurements at the Tevatron
Abstract:
The CDF and D0 experiments at the Tevatron proton-antiproton collider are producing exquisite new measurements of high-Pt processes with the 1 fb^(-1) of luminosity so far collected at sqrt(s)=2 TeV. Recent advances and new methodologies have allowed to measure the top quark mass with a precision of 1.3%, and the top pair-production cross section is known with an experimental accuracy which now surpasses theoretical predictions. The large datasets of leptonic W and Z decays are being exploited for several electroweak measurements. The Higgs boson is being sought in all possible decay modes, and present limits on its production confirm past predictions that an extended running of the Tevatron could allow CDF and D0 to discover that particle if its mass is light, or exclude its existence in a broader mass range. The most interesting results on the above topics will be reviewed, with an emphasis on the reach of Tevatron experiments in the next three years.
The Say of the Week June 28, 2006
Posted by dorigo in games, humor.4 comments
“No! I vermi carnivori no!” (No! Not the meat-eating worms!)
Ornella Muti, in “Flash Gordon”
End to a line of research June 28, 2006
Posted by dorigo in news, personal, physics.3 comments
Today the CDF-Padova group had a marathon meeting in order to discuss a plan for the next three years.
I will give some more detail on it later, but suffices to say that we sort of agreed to something I consider rather crazy.
Basically, despite the fact that our group has been very successful with measurements in CDF using hadronic jets and all-hadronic signatures, and despite the fact that we recently demonstrated how to extract top quark decays in a way nobody had thought of before, producing CDF’s third-best cross section measurement in that sample, we decided to abandon the research on top quark physics altogether. Not an executive decision yet, but a green light to it.
This is very sad and difficult to accept for me, especially since that line of research would provide an opportunity of producing lots of physics measurements in the top quark sector, with minimal effort. Maybe four or five papers in the next three years, authored by us.
Others in CDF will hopefully continue our work…
The problem has to do with the fact that next year I will invest 70% of my time in CMS, and the three other staff members prefer to join in the forces for the search of the Higgs boson with an improved trigger. More on that later.
They killed Bruno June 27, 2006
Posted by dorigo in news, politics.1 comment so far
The bastards.
I am really pissed off. The regional Ministry of Environment of Munich has announced today that the brown bear who had wondered away from its residency in a national park of the italian Alps has been shot dead by hunters in the Miesbach county, in Bavaria.
Bruno was a 2 year old bear. It was born from the mating of Jurka and Joze, and resided in the Brenta-Adamello park until he wandered to Austria and then to south Germany, a few weeks ago. He was part of a project to reinstall the presence of brown bears in the central Alps.
The bear had caused concern for the danger it could pose to human beings. Attempts at catching it alive failed - but were carried out by not specifically trained teams of hunters with dogs, not a smart thing to do. The italian WWF had attempted at providing help for a bloodless catch, but the help had been refused by german authorities (or so I read).
After a few weeks, the bear had been declared a danger and local authorities had issued a death sentence.
That does it. Bavarian soil will not bear my feet nor benefit of my wallet for a long time to come.
Democracy at work June 27, 2006
Posted by dorigo in news, personal, politics.9 comments
Yesterday Italy chose to nullify through a Referendum the attempted modification of the italian Constitution that the former government, led by Silvio Berlusconi, had passed in a rush without any attempt at an agreement with the opposition last November.
More than 50% of the eligible voters said “NO” to the proposed modifications with a 61.3% majority. The center-left coalition who is now governing the country had asked for a No, while center-right parties where united in asking for a Yes.
I plaud at the result, which avoided a very nasty turn toward a more authoritarian system where the Prime Minister would be given too much power, without any counterweight.
What is most relevant to me about yesterday’s results, however, is that a little more than half of eligible voters did cast a vote. I think that percentage is roughly equal to the fraction of people who understand anything about politics in Italy, although I would deny an identity of the two categories in this particular case.
Political elections draw as many as 90% of the voters to the electoral booths, as the recent April elections have shown. In that case, too many people vote in my opinion: many of them know nothing else than what they learn from TV programs, and they decide in what direction to cast a vote based only on the promises of this or that political leader - typically, they vote for whomever promises less taxes.
I think that the whole idea of democracy - a political system where you get to decide with your vote who governs the country - is a great thing, but I think it should be perfected. My vote should not count just as much as that of an illiterate who knows nothing about how the system works.
The difference between yesterday’s participation and that of April speaks volumes about the will of my countrymen to participate in the decision making process: many, probably more than a third of italian electors, are disgusted by politics, politicians, and the whole business of the administration of the country, and care only about their narrow, personal interest -often neglecting that of their siblings.
I am not proposing an oligarchy. What I am trying to say is that I would support a system where in order to cast a vote you would have to pass an exam. An exam where you would have to demonstrate that you know how laws are made, what powers are given to our Premier, what are the rules of the game. In it, potential electors would have to show that they understand what it means to have a 108% /GNP debt, that they understand where taxpayers moneys go, and that they can connotate the two main political coalitions in terms of simple sentences.
The exam could be attempted as many times as one wants, maybe at six months intervals. It could be taken by people of whatever age, even 10 year olds. It would be not too hard, but not overly easy either.
Otherwise, why should people have to pass an exam in order to drive a car, and be eligible to decide who governs my country without demonstrating that they understand what that means ?
Astronomy and weight lifting June 26, 2006
Posted by dorigo in astronomy, personal, science.add a comment
Clear skies over Veneto were predicted for Saturday night by most computer models. My dobsonian 16" scope was impatiently waiting for the occasion of showing me some faint fuzzy in a dark background through non-light-polluted air… Mauro da Lio, a professor of Engineering and peer dark-sky-object observer, had declared his availability to a trip to the mountains. I decided I would take the occasion.
I arrived home from Cavallino, where my family is spending the holidays, at 5PM. I had hard work ahead of me. Here is the sequence of actions that I needed to carry out in order to have the telescope in the trunk of my car by sunset:
- extract the 25lb mirror from the telescope base, store in foam
- carry the 45lb telescope base to my car - a 800m trip through four apartment floors, three bridges, and half-naked tourists, under hard-hitting sun and 35 degrees celsius
- store base in car, go back home
- pack upper cell of telescope, pack eyepieces, pack truss poles
- transport mirror to car under same conditions. The mirror's upper surface cannot be touched (no protective layer of silicon oxide coating -a protective measure- has been applied, to maximize light reflection!) so the 16" bulky glass has to be carried in an awkward position, as taking a cake from fridge to table, with lots of strain on arms muscles
- go back home, take upper cell and truss poles, carry to car
- go back home, take shower, carry eyepiece case to car.
So it took me about two hours… Am I crazy ? A little bit. But I did get to see marvelous things during the night. A list of the objects we observed:
- M13, M10, M12, M71, M56, M22: globular clusters
- M57, NGC6543, M27, M97: planetary nebulas
- M11, M24: open clusters
- NGC7331, M51, NGC6209: galaxies
- M8, Eagle nebula, Lagoon nebula: emission nebulas
One of the most satisfactory views was to see NGC6543, the "cat's eye" planetary nebula, with its central star, at high magnification: simply a wonderful view.
Detailed balancing for garbage collectors June 25, 2006
Posted by dorigo in games, mathematics, personal, physics, science.add a comment
Detailed balancing is a principle which, in its simplest form, relates the relative population of two states by the probability of a transition between them. The principle applies equally well to physical systems, mathematical probability densities, or statistical processes in a variety of forms.
Yesterday I was sweeping the floor of the apartment we rented at Cavallino, by the beach. The floor is made of white tiles, and it is always dirty - or so it looks - because my kids come and go from the beach and bring home lots of sand. The combination of lots of small particles and a white floor triggered my imagination, while I tried to be tidy and do the work as well as I could - and in the smallest possible time, of course!
When you sweep the floor you have two strategies, basically. You can sweep a small area and collect the garbage -sand, in my case- there, then moving on to the neighboring area. Or, you can sweep a large area by bringing along what you have been collecting, until you gather a larger amount of sand, and only then you "stop at the boxes" and take a pause to collect it. Normally, you would use the second strategy, because by minimizing the number of times you collect the garbage, you save time. Ok, but how much can you wait before stopping at the boxes ?
The question is meaningful, of course, since when you bring along more and more sand with the broom, you will continue to collect what you are sweeping, but a small amount of what you have been sweeping will leak out of the moving pile. If the pile is large enough, more sand will leak out than you can collect with the same movement.
A detailed balancing condition has arisen! Let's put it in math terms: if Na is the number of sand grains in a unit area of the floor to be swept, and Ns is the number of sand grains in the pile you are bringing along as you sweep the floor, you can write:
Ns P(s->a) = Na P(a->s)
where P(s->a) is the probability that while you sweep a unit area of floor, a sand grain collected by the broom leaks out, and P(a->s) is the probability that a sand grain on the floor will be collected as you sweep the unit area over which it sits.
I would say that in my case P(s->a) was of the order of 1%, and P(a->s) was 99%. What that means is that I reach an equilibrium condition as soon as Ns is 99 times Na. For instance, if there are 100 grains per tile, then by the time I have collected 9900 grains I can stop sweeping and have better collecting, since my pile won't grow any larger!!
Actually, much earlier than that, because already when I have 5000 grains I start losing 50 every 99 that I collect: my efficiency of collection has dropped by 49%!
All this is very instructive. I had never had the occasion of observing the principle at work in so simple a system… The white tiles are a perfect sand detector. You can actually see what is going on… Almost.
Ah, these crazy particle physicists…
Notice to users June 25, 2006
Posted by dorigo in internet, news.2 comments
Spam comments filtered out by my filter have soared to more than three hundred daily.
Under these conditions, I cannot check the filtered comments, and have to delete them without looking at them.
If you post a comment here, be sure to avoid including more than one link. Also, avoid words usually filtered out by spam-aware software.
Thanks!
Tommaso
