Physics

Today I wish to offer you, dear reader, the chance to contribute to scientific research in particle physics. And I claim you can do that by only leveraging basic high-school knowledge in mathematics and geometry. Let me explain what the problem is, first of all, and then I'll put you in the conditions of contributing! Muons are subnuclear particles of high interest in collider physics. I could write about muons for ages, but it would not be of relevance for our problem of today, so let's just say they interact feebly with matter, so they traverse thick layers only depositing in them small…

Eight years ago the CMS and ATLAS experiments, giant electronic eyes watching proton-proton collisions delivered in their interior by the CERN Large Hadron Collider (LHC), discovered the Higgs boson. That particle was the last piece of the subnuclear puzzle of elementary particles predicted by the so-called "Standard Model", a revered theory devised by Glashow, Salam and Weinberg in 1967 to describe electromagnetic, weak, and then strong interactions between matter bodies. The Higgs boson itself is even older, having been hypothesized by a few theorists as far back as 1964 to explain an…

A Theory of Everything has been the subject of many pages of journals and of much more ink spilled. Sean Carroll makes the point that at low energies, and within a domain of validity that applies to every day physics, we have such a theory already.  Everyday high energy physics, every day astrophysics and of course the physics of your daily life are all well understood.  A Theory of Everything would really be a theory about that singular event from which everything we can know of sprang, the big bang. Also good luck and godspeed to Jim Bridenstine, Lady Gaga inagurated the first…

Broadly speaking, radioactivity is not something one should mess with just as a pastime. Indeed, ionizing radiation has the potential of causing carcinogenic mutations in your cells DNA, as well as produce damage to cell tissue. Indeed, it makes me chuckle that until 50 years ago or so kids could play with it by purchasing stuff like that shown below... If you know what you are dealing with and take the necessary precautions, however, radiation _can_ be fun to study at home. The tools and the primary matter are not found at the corner grocery, though, so you need to have a specific interest…

Everybody would agree that 2020 was a difficult time for all of us - the pandemic forced on us dramatic changes in our way of living, working, and interacting with one another; and let's leave alone the horrible, avoidable death toll that came with it. Notwithstanding, for some reason it was a productive year for me, and one which has potentially paved the ground for an even more productive future. Below I will summarize, if only for myself, the most important work milestones of the past year, and the ones that lay ahead in the forthcoming months. But I will also touch on a few ancillary…

For the (likely going to be dramatically unsuccessful) series "Questions you would have liked your son asked you when you visited CERN together", I feature today a rather unconventional curiosity about LHC and neutrino physics. The source of inspiration for this is a coffee-time conversation I had long ago, I don't even remember with whom - probably a colleague. Anyway, that's the least interesting bit of the whole matter.The LHC is...Let us start with the basics. What is the LHC ? LHC stands for "Large Hadron Collider". Located 100 meters underground at the CERN laboratories near the town of…

Gravitational waves and particle physics experiments being mixed is  something  I  have theorized  about for  a couple of years (1).     Now a new paper by  Suvrat  Rao,  Marcus  Brüggen, and  Jochen  Liske has  taken  this to  another  level (2).   They have worked out and demonstrated in detail how a circular particle accelerator such as the LHC could be used to observe gravitational waves in the mHz range.  This differs from experiments such as LIGO and LISA in the…

Nearly all of the atoms that make up the our planet and us were forged in stars and the carbon most important to life as we know it was made by the triple-alpha process. The process starts with alpha particles, cores of helium atoms, with each alpha particle is made up of two protons and two neutrons. The triple alpha process is just what it sounds like; three alpha particles are fused inside a star, creating a new particle with six protons and six neutrons - the most common form of carbon in the universe - with a surplus of energy, a Hoyle state. That Hoyle state can split back into three…

That's right - I finally hit the ground with my creativity, and my jokes are starting to use old material for my post titles. Yet producing a pair of Higgs bosons in a proton-proton collision is seriously cool indeed. The Higgs boson in fact is one of the few particles that does a trick called "self-coupling": in a sort of ermaphroditic act it is capable of giving birth to a pair of objects identical to itself. Self coupling is possible to bosons, particles that carry interactions among matter fields, if they possess the charge of the field of which they are the messengers. Take the…

I was blissfully unaware until today of a slightly anomalous effect, which was found by the ATLAS Collaboration when performing a search for top pairs plus Higgs bosons in their Run 2 data. The anomaly I am talking about is an apparent excess of events which could be explained, as ATLAS did in this preprint article, by dialing up the cross section of some background processes producing a top pair and a W boson.  Since the ATLAS analysis is concerned with measuring the rate of the rare, and interesting, process of production of a Higgs boson in association with a top quark pair (see below…