A Quantum Diaries Survivor

I was delighted to receive news this afternoon of three new interesting results produced by the DZERO collaboration in the analysis of Quantum Chromodynamics (QCD) processes.QCD, the theory of strong interactions between quarks and gluons, is the "boring" part of the physics of high-energy hadron-hadron collisions. It used to be more more exciting twenty years ago, when the theoretical calculations were not as refined as they are now, and there was still a lot to understand in the physics of strong interactions between quarks and gluons. But nowadays, things are much more clear.

How do we fix science journalism ? Simple: we don't. We let it sink, and be reborn in a different form.It is rather utopic to insist that in a world of changing means of communications, a world where printed matter is losing ground to the advantage of electronic media, the diffusion of scientific information may or shall stay the same.

Yesterday somebody asked me here if I could explain how does a muon really decide when and how to decay. I tried to answer this question succintly in the thread, and later realized that my answer, although not perfectly correct in the physics, was actually not devoid of some didactic power. So I decided to recycle it and make it the subject of an independent post. Before I come to the discussion of how, exactly, does a muon choose when and how to decay, however, let me make a few points about this fascinating particle, by comparing its phenomenology to that of the electron.

The CDF collaboration has recently released new results from a search for what is probably the clearest signature of Higgs boson decay: pairs of high-mass photon candidates. I am very glad to see this new analysis out for publication, since so far only DZERO, CDF's competitor at the Tevatron, had produced results on this particular final state.

One of the few physics measurements that the LHC experiments are already in the position of producing, with the week-worth of proton-proton collision data they have collected last December, is that of the Bose-Einstein intereference between identical bosons.

There are twenty-four elementary fermions in the standard model. Sure, they are arranged in a very tidy, symmetrical structure of three families of eight fermions (two leptons and six quarks), which is not too unpleasant to behold. And of course, if one is willing to forget the fact that the quantum-chromodynamical charge of quarks does make them different, then the picture is even tidier: 12 fermions, six of them quarks and six of them leptons, arranged in three families of four.

One of the positive side-effects of preparing a seminar is being forced to get up-to-date with the latest experimental and theoretical developments on the topic. And this is of particular benefit to lazy bums like myself, who prefer to spend their time playing online chess than reading arxiv preprints.It happened last week, in the course of putting together a meaningful discussion of the state of the art in global electroweak fits to standard model observables, and their implications for the unknown mass of the Higgs boson: by skimming the hep-ph folder I found a very recent paper by a colleague in Padova, which I had shamefully failed to notice in the last couple of careless visits.

This morning, upon leaving Brussels to go back home after my seminar in Louvain-la-Neuve, my attention was caught by a big green banner hanging from a tall building at Place Schuman. It said "Safe Internet Day" and below, in smaller fonts, "think before you blog". I found it inspiring.A blog, if used correctly, is a very nice tool which enhances one's possibility to express one's ideas, or to do scientific outreach, as in my case. It may also be used for self-promotion at times (and the opportunity does not escape me, although I try to self-contain these outbursts). But a blog, if it attracts traffic, may become also a dangerous instrument, which must be handled with care.

To see the future, you must know the past: these nine words nicely summarize a syllogism which knows few exceptions. Turning to known data to check the power of one's extrapolations is a quite well-founded scientific approach. So if we are to try and guesstimate how much will the CDF and DZERO experiments manage to deliver in the next few years, we must check how well they delivered this far, by comparing results with early expectations. But why bother ? Well, of course because there is a real challenge on: bookmakers need to tune the odds they offer!Fermilab versus CERN

Last Friday I was in Pisa, at the Scuola Normale Superiore (see picture), where italian members of the CMS Collaboration gathered for two days to discuss the status of their studies, exchange ideas, and try to coalesce common analysis efforts.

W bosons are amazingly interesting objects. Almost thirty years after their discovery -by Carlo Rubbia and his collaborators of the UA1 experiment at CERN- they continue to provide critical information on the theory of electroweak interactions. The front of particle physics has moved quite a bit further from 1983, and yet the weapons we use todat to try and conquer unexplored land have not changed much. Today I wish to summarize one particular search that has been done by the CDF experiment at the Tevatron proton-antiproton collider, one which tries to catch W bosons as they decay in a very uncommon way.

A weekly visit to the Cornell Arxiv is more than enough for a physicist like me, since my daily work is not affected too much by whatever happens to be published there. Oftentimes, when I browse the contents of hep-ph (the folder containing preprints on particle phenomenology) I do not end up actually reading any papers, and limit myself to "sniffing" what is going on, by looking at the titles and author names. But at times I venture to browse through the pages, with mixed results.