General Public - Particle Physics and Gravitation

Particle Physics is the branch of Physics that studies the constituent particles of matter and radiation and their interactions. It is also called High Energy Physics, because most of the studied particles cannot be found spontaneously in nature, but must be created through very energetic collisions with other particles, normally in particle accelerators.

The ICC participates in several international projects related with particle accelerators. In particular, the Experimental Group of High Energy Physics collaborates in the construction of the LHCb detector of the LHC accelerator, in the BABAR experiment of the PEP-II accelerator, and in the design study of the future ILC.

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The theory that describes all particles known up to the now is the Standard Model. The basic constituents of the Standard Model are elementary particles, which are classified in two groups: matter particles and force carriers. The model also predicts the existence of a so far undiscovered particle, the Higgs boson, which would interact with the other particles and fields to give masses to them..

The ICC study the Standard Model and those extensions that could enlarge the theory and convert it in a Theory of Everything. This research is carried out by our High Energy PhysicsTheory Group.

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Particle Physics is necessary to understand the History of the Universe, since according to the present models, the Universe was born in the Big Bang and, in its first seconds of life, it was a soup of extremely energetic particles. The experiments made in large particle accelerators are supposed to recreate those first seconds of the Universe. Besides, cosmologists and astrophysics also need Particle Physics to determine which kind of matter form the present Universe. In fact, only a small fraction of the matter content of the Universe is known; most of the matter is of a nature unknown to us. It is known to particle physicists and astrophysicists as Dark Matter. Astrophysics, Cosmology and Particle Physics have thus common interests and must work together.

The ICC wants to promote common projects among these research areas. It gathers researchers from the departments of Astronomy and Meteorology, Structure and Constituents of Matter and Fundamental Physics, and also collaborators from other departments.

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At least four fundamental forces exist in nature, but the Standard Model of particle physics includes only three: electromagnetic, weak and strong interactions. The gravitational force is described by a theory of completely different nature: General Relativity, the Einstein's theory of gravity. The aim of string theory is to unify General Relativity to quantum field theories, the framework in which we understand the three other forces.

Researchers at ICC study General Relativity and superstring theory, which accomodates the four fundamental forces of nature in a single unified quantum theory.

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Learn about Particle Physics


  • EPPOG (European Particle Physics Outreach Group) - Its web page about its masterclasses and physics pages, such as:
    • Hands on CERN - A web page aimed at teachers and high school students studying natural sciences. The purpose of this project is to increase understanding of the most fundamental processes inside matter, and to explain modern research about particle collisions. After an introduction to the theoretical description of particle physics and the experimental techniques there is the chance to make several measurements with real events recorded by the DELPHI experiment in particle collisions at CERN.
    • Identifying Particles - The purpose of these web page is to allow you to identify for yourself some interesting particle physics interactions or "events". These events have been seen using an experiment called OPAL, at CERN, near to Geneva. The experiment ran from 1989 to 2000 at the Large Electron-Positron collider (LEP), which was installed in the largest particle accelerator tunnel of the world.
Other sites
  • The particle adventure - A web page about the fundamentals of matter and force. An interactive tour of quarks, neutrinos, antimatter, extra dimensions, dark matter, accelerators and particle detectors.