A Quantum Diaries Survivor

(The XVIth edition of "Neutrino Telescopes" is going on in Venice this week. The writeup below is from a talk by M.Nakahata at the morning session today. For more on the conference and the results shown and discussed there, see the conference blog.)

During the first afternoon session of the XVI Neutrino Telescopes conference (here is the conference blog, which contains a report of most of the lectures and posters as they are presented) Francis Halzen gave a very nice account of the discovery of cosmogenic neutrinos by the IceCube experiment, and its implications. Below I offer a writeup - apologizing to Halzen if I misinterpreted anything.

The paper to read today is one from the ATLAS collaboration at the CERN Large Hadron Collider -my competitors, as I work for the other experiment across the ring, CMS. ATLAS has just produced a new article which describes the search for the CP-odd A boson, a particle which arises in Supersymmetry as well as in more generic extensions of the Standard Model called "two-higgs doublet models". What are these ?

"1. Interaction with matter changes the neutrino mixing and effective mass splitting in a way that depends on the mass hierarchy. Consequently, results of oscillations and flavor conversion are different for the two hierarchies.2. Sensitivity to the mass hierarchy appears whenever the matter effect on the 1-3 mixing and mass splitting becomes substantial. This happens in supernovae in large energy range, and in the matter of the Earth.[...] 4. Multi-megaton scale under ice (water) atmospheric neutrino detectors with low energy threshold (2-3 GeV) may establish mass hierarchy with (3-10)σ confidence level in few years. [...]

Less than three weeks separate us from the XVI Neutrino Telescopes, a very interesting conference held in Venice every two years. The physics of neutrinos is a very special niche in the realm of particle physics, one not devoid of cunning experimental techniques, brilliant theoretical ideas, and offering possible avenues to discover new physics. Hence I am quite happy to be attending the event, from where I will also be blogging (hopefully with the help of a few students in Padova).(NB this article, as others with neutrinos as a subject for the next month or so, appears also in the conference blog).

A preprint article by the IceCube collaboration captured my attention today in the Cornell Arxiv, and even more interesting was the main result of the analysis it reports, which can be shown as a "temperature plot" on an equilateral triangle. We will get to that, but let me first explain what is the experiment, what are the goals, and what it is that was measured.

The sixteenth edition of the internationally known Neutrino Telescopes conference will take place on March 2nd-6th 2015 in the usual venue of Palazzo Franchetti in Venice. This is a conference which gathers from around the world researchers who study neutrino physics and related topics. 

James D. Bjorken, also known as "BJ" by colleagues and physicists around the world, has been awarded the prestigious 2015 Wolf prize in Physics together with cosmologist Robert Kirshner. Bjorken deserves a lot of credit for his contribution to subnuclear physics: the official motivation is "For predicting scaling in deep inelastic scattering, leading to identification of nucleon's pointlike constituents "

ATLAS sent today to the Cornell arxiv and to the journal JHEP their latest measurement of the top-antitop production asymmetry, and having five free minutes this afternoon I gave a look at the paper, as the measurement is of some interest. The analysis is done generally quite well, but I found out there is one things I do not particularly like in it... It does not affect the result in this case, but the used procedure is error-prone. But let's go in order. First I owe you a quick-and-dirty explanation of what is the top asymmetry and why you might care about it.

The publishing giant Elsevier is about to launch a new journal, Reviews in Physics. This will be a fully open-access, peer-reviewed journal which aims at providing short reviews (15 pages maximum) on physics topics at the forefront of research. The web page of the journal is here, and a screenshot is shown below.

The CMS collaboration has released yesterday results of a search for Majorana neutrinos in dimuon data collected by the CMS detector in 8 TeV proton-proton collisions delivered by the LHC in 2012. If you are short of time and just need an executive summary, here it is: no such thing is seen, unfortunately, and limits are set on the production rate of heavy neutrinos N as a function of their mass. If you have five spare minutes, however, you might be interested in some more detail of the search and its results.

A periodic backup of my mobile phone yesterday - mainly pictures and videos - was the occasion to give a look back at things I did and places I visited in 2014, for business and leisure. I thought it would be fun to share some of those pictures with you, with sparse comments. I know, Facebook does this for you automatically, but what does Facebook know of what is meaningful and what isn't ? So here we go.The first pic was taken at Beaubourg, in Paris - it is a sculpture I absolutely love: "The king plays with the queen" by Max Ernst.Still in Paris (for a vacation at the beginning of January), the grandiose interior of the Opera de Paris...