Physics

I was very saddened the other day upon learning from a colleague that Teresa Rodrigo Anoro passed away. Teresa was a professor at IFCA, University of Cantabria in Santander, Spain, where she held the position since 1995. At the IFCA she led a strong team of experimental particle physicists who collaborate to the CMS experiment at the CERN LHC. Her premature loss leaves a very large void at her institution in particular, as well as in the development of Spanish particle physics in general, where she had a big role. It is not my job nor my immediate wish to describe here the many ways in which…

These days I have been writing a chapter of a book on machine learning for physics, and in so doing I have found myself pondering on how to best explain, in very simple terms, the nocuous effect that model uncertainty may have on the result of a classification task. So I decided to create a toy example with the purpose of introducing the discussion. The example is meant to have two attractive properties: be analytically solvable in closed form - meaning that one may compute with paper and pencil all the relevant results - and be described by simple-to-interpret graphs. Below I will describe…

The isolation that most of the civilized world has been subjected to, during the past few weeks, has produced a number of nasty effects, first and foremost on our economies, but it has also had a few positive ones. One of them is, at least in my case, an urge to use the extra time I have in my hands in a creative way. Being an avid mineral collector, my house is full of specimens. They appear a bit everywhere in display cabinets and book shelves. Over the years I have collected over 300 pieces, plus a hundred gemstones, and I remember of course almost everything about each of them, from where…

In a recent post I discussed the conclusions of a study aimed at computing a small but very important correction to the theoretical prediction of the anomalous magnetic moment of the muon. The interest of this lays in the fact that the latter quantity is virtually the only one for which the Standard Model prediction exhibits a tension with the current experimental measurements among all the measurable parameters of the subnuclear world. In a nutshell, while all the previous similarly cooked up theoretical estimates of that correction (which is called, in case you care to know, "next-to-…

First off, let me say I do not wish to sound disrespectful to anybody here, leave alone my colleagues, to most of which goes my full esteem and respect (yes, not all of them, doh). Yet, I feel compelled to write today about a sociological datum I have paid attention to, in these difficult times of isolation, when all of us turn to the internet as our main outlet for rants, logorrhea, or to make the impending threat of a global catastrophe less heavy by sharing it with our peers, to exorcise our fears. Physicists are accustomed, in their day to day activities, to think rationally about…

A new long article which appeared on the arXiv preprint repository last week is sending ripples around the world of particle physics phenomenology, as its main result -if proven correct- will completely wipe off the table the one and only long-standing inconsistency of the Standard Model of particle physics, the one existing between theoretical and experimental estimates of the so-called anomalous magnetic moment of the muon. Now, I think all my colleagues would agree that explaining what is this quantity we call "anomalous magnetic moment of the muon" in layman terms is no joke;…

Tomorrow morning the Cornell arXiv will publish the preprint of a long scientific article, the result of 4.5 months of painstaking work by yours truly. So I thought I would give you a preview of its contents. Of course, it will take more than a single post to do a good job - I guess I can describe the generalities here, and leave it to another time the plunging into technical details that may only be interesting to insiders. First of all, what experiment are we talking about? It is called "MUonE", and it aims at measuring with the utmost precision the rate at which muons scatter elastically…

Waves of geometry in four-dimensional space-time, that is what gravitational waves are.  The very definition of distance between points in space-time changes as these waves pass.   The objects in the space do not move but space itself changes momentarily.  The scale at which these changes can be measured right now are on the order of a few dozen widths of a proton.  Smaller than the average distance between the electron and proton in a hydrogen atom.   Yet, with laser light shining through interferometers, we can measure these changes.  From these we…

A few days ago I received from my esteemed colleague Massimo Passera, a theorist and an INFN director of research in the Padova section where I also work, a draft of a new article he produced with his colleagues Antonio Masiero and Paride Paradisi, which is relevant to my present interests. The paper discusses what new physics effects could be accessible by the precision measurement of elastic scattering of energetic muons off electrons, in a setup which is being considered at the CERN north area for the determination of the hadronic contribution to the effective electromagnetic coupling (the…

The Tevatron collider, the giant marvel accelerator built at the Fermi National Accelerator Laboratory in the eighties and operated there for over thirty years, until its demise in 2012, lost one of its fathers the other day, as Alvin Tollestrup passed away. Tollestrup was maybe the key contributor to the project of putting together a 1-TeV particle accelerator, solving many issues for the construction of its superconducting magnets. But he also was for a long time the spokesperson of the CDF experiment, and the driving force behind the collective effort that led CDF to see a first evidence…