CMS

The likelihood is dead, long live the likelihood

Among the sciences, particle physics has the luxury of having a well established theoretical basis. Often we focus on the elementary particles and model them mathematically with quantum field theories like the Standard Model. In order to compare…

CERN's new open data policy supports open science

The four main LHC collaborations (ALICE, ATLAS, CMS and LHCb) have unanimously endorsed a new open data policy for scientific experiments at the Large Hadron Collider (LHC), which was presented to the CERN Council today. The policy commits to…

Machine learning ushers in a new paradigm for particle searches at the LHC

Searching for physics beyond the Standard Model (BSM) is a major part of the research programme at the LHC experiments. Nearly all of these searches pick a signal model that addresses one or more of the experimental (e.g., dark matter) or…

CMS GEMs are changing gear

It can be called the achievement of the year for the CMS Muon GEM group, culminating on a decade-long effort and development of knowhow. The Gas Electron Multiplier (GEM) is a Micro Pattern Gaseous Detector (MPGD) widely used in particle physics.…

What is the likelihood function, and how is it used in particle physics?

In statistical data analysis, “likelihood” is a key concept that is closely related to, but crucially distinct from, the concept of “probability”, which is often a synonym in everyday English. In this article, I first lay some necessary…

CMS restarts and continues working under Covid-19 conditions

One of the major objectives of CMS for LS2 is an early phase-2 electronics upgrade of the Cathode Strip Chambers (CSC), located on all three endcap disks, and the installation of one layer of triple Gas Electron Multiplier Chambers (GEM) on the…

CERN experiments find first evidence for rare Higgs boson decay

The strength of the interaction between the Higgs field and a particle determines the mass it obtains from the Higgs and it is a mystery why the interaction strength is different for different particles. This puzzle is exacerbated as the leptons,…

How to search for new physics without knowing about it?

BSM searches at the LHC increasingly profit from ML techniques since this approach allows more general searches that minimise the probability of missing evidence of new physics. Very recently, the ATLAS collaboration has published a novel approach […

LHC experiments ramp-up activities

Around the world,research centres, laboratories and universities have closed as a response to the COVID-19 pandemic — forcing an increasing number of researchers to work from home. Researchers teleworking coordinated with colleagues who had to…

CMS weighs in for the top quark

The top quark has a special position in the zoo of elementary particles, being the heaviest as well as one of the rarest fundamental particles ever sighted. With a mass of about 173 GeV, it has 40 times the mass of its partner, the bottom quark and…

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