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The Large Hadron Collider and the Standard Model

Prelims and MainsCurrent affairs on this: Physics, chemistry and mathematics in news

The Large Hadron Collider at CERN near Geneva is a 27 km ring in which two beams of protons travel in opposite directions at close to the speed of light and are made to collide inside four detectors, ATLAS, CMS, ALICE and LHCb. Two things decide what a collider can find: energy, because a heavier particle needs more energy to appear, and luminosity, the number of collisions per second, because a rare particle appears in only a few collisions in a billion. The Standard Model is the theory of the particles and forces the collider tests: six quarks, six leptons, the force carriers, and the Higgs boson, whose field gives the other particles their mass. The LHC found the Higgs in 2012. India has been an associate member of CERN since 2017, built parts of the CMS and ALICE detectors, and supplied magnets from RRCAT, Indore.

The Large Hadron Collider

The Large Hadron Collider ring and its two dials A ring with two proton beams travelling in opposite directions, the four detectors ATLAS, CMS, ALICE and LHCb at four points on it, and two dials: energy, which finds heavier particles, and luminosity, which finds rarer particles. ATLAS CMS ALICE LHCb 27 km ring near Geneva Beam 1 Beam 2, opposite way Energy finds heavier particles Luminosity finds rarer particles
Energy and luminosity are separate dials; the 2026 upgrade turns only the second.Source: CERN
  • Energy sets which particles can appear; luminosity sets how often a rare one is seen. An upgrade can raise either.
  • The four detectors divide the work: ATLAS and CMS are general purpose, ALICE studies heavy ion collisions, LHCb studies the bottom quark.
  • The Higgs boson, found in 2012, completed the Standard Model; what the model still cannot explain is gravity, dark matter and why matter outweighs antimatter.
  • India: associate member since 2017; contributions from the Bhabha Atomic Research Centre (BARC), the Raja Ramanna Centre for Advanced Technology (RRCAT), the Tata Institute of Fundamental Research (TIFR) and universities.

UPSC has asked

  • Prelims 2013: the four known forces of nature and their properties
  • Prelims 2013: the importance of discovering the Higgs boson

See also: India at FAIR