The most powerful particle collider in the world, the Large Hadron Collider (LHC), was built in the 27 km tunnel originally excavated for the highest energy electron-positron collider ever built, LEP. As an extraordinarily sensitive machine, LEP was…

Using the golden decay channel to understand the production of the Higgs boson The standard model of particle physics is currently the best way to describe interactions of fundamental particles that make up our Universe. It has been tested over many…

What does the decay of a bottom quark look like? Fragmentation, also known as hadronization, is when particles that contain quarks or gluons create other particles via the strong interaction. The fragmentation process cannot be exactly…

A shot in the dark: Can jets recoil against Dark Matter? In their 2020 hit single ‘A Shot in the Dark’ the rock band AC/DC got it right in many ways: “A shot in the dark  Make you feel alright  A shot in the dark  All through the…

Using machine learning to improve the detection of new physics in the interactions of the top quark   Although our theory describing the interactions between fundamental particles is exceptionally successful, it has weaknesses. You may have…

Quarks are elementary particles in the Standard Model and the building blocks of the protons and neutrons in atoms. The dominant force between quarks is the strong interaction. Gluons are the force carriers of the strong interaction, and one thing…

In the LHC, groups of 100 billion protons collide 25 million times every second. But most of these protons miss, so each time we point the protons at each other doesn't give us 100 million proton-proton collisions.  In fact, collisions are much…

The CMS collaboration has submitted a paper with a new, precise analysis of the data enriched in the Higgs boson decays to four leptons. Simultaneous measurement of the Higgs boson production and decay was essential in this analysis.  The…

Experimental evidence from the last half-century has established the standard model as a foundational theory of particle physics. Still, it is clear that the standard model is not the final theory. There are many open questions: Is the mass of Higgs…

The Standard Model of the fundamental particles describes the W and Z bosons as the mediator particles of the weak force, one of the four known fundamental forces responsible for the phenomenon of radioactivity and an essential ingredient to our Sun…

Since the LHC first began colliding protons over ten years ago, CMS physicists have hoped to find evidence for one of the most popular and expansive theories of New Physics -- Supersymmetry.   The key idea of Supersymmetry (or “SUSY”) is…

The term 'flavor' was introduced by Murray Gell-Mann and his student Harald Fritzsch to describe the different types of quarks known at the time – up, down, and strange – the list of quark flavors grew to six. The term is adapted for the lepton…