It feels good, for a die-hard sceptic like I am, to live and let unexplained phenomena die. The phenomena in question are measured deviations from the predictions of the Standard Model (SM), our wonderful theory of subnuclear interactions, which has been condemned to fail by theorists soon after its construction, but continues, disappointingly for many, to succeed in explaining experimental results.
'True muonium' is a long-theorized but never-seen tiny atom that was first proposed more than 50 years ago. True muonium, which unlike "muonium" (an atom made of an electron and an anti-muon) is made of a muon and an anti-muon. Both muons and anti-muons are created frequently in nature when energetic particles from space — cosmic rays — strike the Earth's atmosphere yet their existence is fleeting and their combination, 'true muonium,' decays naturally into other particles in a few trillionths of a second. This has made observation impossible.
But it might be observed even in current collider experiments, according to theoretical work published recently by researchers at the SLAC National Accelerator Laboratory and Arizona State University.
This is going to be a rather long piece, so for the lazy and the absent-minded among you I decided to put together an executive summary at the top, and not at the bottom of the article as I usually do. It is a bit of a spoiler, but those of you who can invest some time reading about particle physics will not be deterred by the first few lines of text. Besides, an executive summary is needed because we are discussing real news here: so here it is.
The "new" section of experimental physics papers in the arxiv today features a preprint by the CDF collaboration, titled "First Observation of Vector Boson Pairs in a Hadronic Final State at the Tevatron Collider". This is another instance of a difficult analysis where the CDF and DZERO experiments have competed in the past, and one which is relevant for Higgs boson searches. And CDF got there first once again.
I will describe in detail the analysis and the results later today, because this particular study is dear to me for at least three different reasons:
This afternoon Lisa Randall, one of the most famous theoretical physicists of our time, received from the hands of Flavio Zanonato
, mayor of Padova, the keys of the city.
This morning the Planck 09 conference
started at the Auditorium Altinate (see picture, right) in Padova. For a week, theorists and experimentalists will discuss hot topics in a variety of fields, from particle physics to cosmology, to string theory. A PDF file with the program is online
When Albert Einstein constructed his general theory of relativity he decided to resort to some reverse engineering and introduced a 'pressure' term in his equations. The value of this pressure was chosen such that it kept the general relativistic description of the universe stable against the gravitational attraction of the matter filling the universe.
A new paper in the Arxiv
attracted my attention this morning. It is titled "Perturbative QCD effects and the search for a
signal at the Tevatron", and is authored by a set of quite distinguished theorists: C.Anastasiou, G.Dissertori, M.Grazzini, F.Stockli, and B.Webber.
Last Tuesday CDF announced their own discovery of the Omega_b baryon, a measurement which creates a controversy with the competing experiment at the Tevatron collider, DZERO. That is because DZERO had already claimed discovery for that particle, almost one year ago, and because the two measurements disagree wildly with each other. Just browse through my past few posts in this column
and you will find all the information you need (how lazy can one be with links?).
In thirty minutes (4 PM Chicago time) a live streaming of the Omega_b discovery by CDF
will be broadcast at this link: http://vms-db-srv.fnal.gov/fmi/xsl/VMS_Site_2/000Return/video/r_live.xsl
Please follow it if you are interested in particle physics - Pat Lukens
, the main author of the analysis, and a very experienced and skilled physicist who has spent the better part of his life for the good of the CDF experiment, will be discussing this fantastic new analysis for all of us.