CMS

Higgs boson and the quest for new physics

The discovery of a new particle in 2012 by the ATLAS and CMS experiments at CERN was just the beginning in understanding the properties of this particle and its potential link to some of the most pressing fundamental questions in modern physics.…

Successful installation of the CMS Pixel Tracker

In early 2019 the CMS Phase-1 Pixel detector was extracted from the underground cavern after successful completion of the LHC Run 2 data taking campaign. Its sub-detectors, the Barrel Pixel (BPIX) and Forward Pixel (FPIX) detectors, were stored cool…

The installation of the beam pipe at the heart of the CMS experiment

After several years of complex design, manufacture and planning, the CMS collaboration, in tight cooperation with experts of the CERN Technology Department-Vacuum, Surfaces, and Coating group, have been installing the new heart of the detector, the…

LHC takes on the SMEFT challenge

The quest for new physics at the LHC is entering a new phase: the experiments are designing new strategies to target potential deviations from the Standard Model (SM) predictions in a systematic way, to complement the traditional “bump hunts” and,…

CMS experiment prepares for Run 3

The CMS experiment is one of the four large experiments at the LHC and a detailed description of the detector's inner and outer layers can be found here. The detector successfully operated with LHC collisions since 2010 leading to the Higgs boson…

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 foundations…

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