Physics

As I mentioned in yesterday's post, there is a workshop going on this week at Fermilab, where 110 attendees - mostly particle physicists, but some computer scientists are also present - discuss how to push for more effective use of machine learning tools in the extraction of information on particle collisions. 

Also one goal is to understand what new ideas from the world of machine learning could find ideal applications in the typical use cases of research in fundamental physics. Here I wish to mention a few interesting things that I heard at the workshop so far, in random order. I will rarely make direct reference to the talks, to encourage you to dig into the pdf files available here.
I flew to the US yesterday to get to Fermilab, where I am following a workshop titled Machine learning for jet physics". My goal of this post is to explain what this is about in general terms, such that if I have enough stamina I will give, in follow-ups to it, a few examples of the status of this interesting research activity, which encompasses particle physics and computer science and can provide spin-offs in a number of related areas of fundamental research.
What is Dark Matter (DM) and why should you care? I feel I should start this article by explaining these two things first, as we live in an age when nobody has time for long historical or context-setting introductions. 
Before you brush off this post with the answer "of course", let me qualify the title. Of course anybody can become a particle physicist, although the learning curve can be steep and hard to climb up. But what I mean here is, can a student who has been trained as a statistician (through his or her bachelor and master degree) become a successful experimental particle physicist, without investing other years of his or her life in studying quantum mechanics and lots of other arcane physics topics ?
Particle physics has been historically the ground of long-standing scientific challenges between the US and Europe, especially since the birth of the CERN laboratories in 1954. And in parallel, another challenge has kept the field alive and thriving for over half a century: the one between theoretical and experimental physics. 

Alessandro Strumia, needs to have had a five minute talk with the late great Ben Barres.  Dr Barres was fond of telling a story where he heard how much his work was “better than your sister’s”.   Ben was a female to male transguy.   For those unfamiliar with the lingo started out a woman … then transitioned to living as a man.    This is a clumsy and non-PC way to put it I know… but when preaching to people one must speak their language.   Transgender scientist can tell you all about how different gender-based stereotypes and assumptions affect us.

The world of particle physics is in turmoil because of a presentation by Alessandro Strumia, an Italian phenomenologist, at CERN's "1st workshop on high energy theory and gender", and its aftermath. 
By now the story has been echoed by many major newscasters around the world, and discussed in public and private forums, blogs, twitter feeds. I wanted to stay away from it here, mainly because it is a sensitive issue and the situation is still evolving, but after all, why not offer to you my personal pitch on the matter? Strumia, by the way, has been an occasional commenter to this blog - you can find some of his comments signed as "AS" in threads of past articles. Usually he makes good points here, as long as physics is the subject.
Casual reader, be warned - the contents of this article, specifically the second part of it, are highly volatile, speculative stuff. But hey, that is the stuff that dreams are made of. And I have one or two good reasons to dream on.


The environment
What is a photon jet? Despite their exotic name, photon jets are a well studied thing nowadays. The original studies were performed by experimentalists who aimed to test quantum chromodynamics: they used to spend their time discriminating prompt photon production in hadron collisions from backgrounds. I remember a lot of such studies were performed in the 80ies and 90ies by my CDF colleagues, especially within the "QCD working group".
The importance of the detection of single, isolated photons of high energy has risen enormously since then, given their role in the discovery of the Higgs boson. Photon jets are in fact the background to beat down if you want a neat peak of H --> γγ decays to pop out of a mass histogram constructed from events featuring two photon candidates.
The famous paradox 'which came first, the chicken or the egg?' was created by philosophers to discuss cause and effect. Since chickens lay eggs, and eggs produce chickens...you get the idea.