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Mass of the proton

Whence comes the mass of the proton?

 Automatic translation  Automatic translation Updated June 01, 2013

Press release " The mass of the proton finally explained " (20/11/2008).
In 95 % of the energy of quarks and gluons, answer the physicists of the Center of theoretical physical appearance of Marseille. Led from the standard model which describes the interactions between elementary particles, their calculations prove that the mass of the proton results mainly from the energy carried by these "elements" that are quarks and gluons, through the famous formula of Einstein E=mc2.
This exploit confirms the validity of a theory to depict the strong interactions between particles. Published in Science November 21st, 2008, these works were carried out thanks to supercomputers among the most powerful to the world.
They allow to envisage the arrival of a new theory in fundamental physics, beyond the current model, with possible discoveries in the field of the weak interactions of quarks. In the nuclei of atoms, we find protons and neutrons. These are constituted of quarks and of gluons, sorts of small fundamental sub-structures themselves. 
The mass of gluons is null. And, contrary to what we could think, mass it quarks which compose a proton represent only 5 % of the mass of this last one. Where from thus result the remaining 95 %? A team of French, German and Hungarian physicists has just proved that these 95 % result from the energy due to the movements of quarks and gluons, and to their interactions. A mass stemming from an energy, it is a little puzzling result, nevertheless translates by the famous formula of Einstein E=mc2 expressing the equivalence between mass and energy. Up to here hypothesis, this result is confirmed for the first time. The researchers, piloted in France by Laurent Lellouch, research director NATIONAL CENTRE FOR SCIENTIFIC RESEARCH in the center of theoretical physical appearance, leaned on more than twenty years of researches made by physicists of the whole world.
Leaving equations of the quantum chromo dynamic, that is the theory which describes the strong interactions, they succeeded in calculating the mass of protons, neutrons and other particles of the same type.


Result, the masses obtained by the calculation are in excellent agreement with those measured experimentally.
The researchers so confirm that the standard model is correct to describe the origin of the mass of these particles and thus that of more than 99 % of the visible universe, including the Sun, the Earth, ourselves and all the objects which surround us.
To reach their purposes, the researchers used an approach where the space-time is envisaged as a crystalline network in four dimensions, consisted of sites spaced out along rows and along columns. Their main challenge was to arrive at a solution which corresponds to our continuous space-time, while checking all the sources of uncertainties bound to the calculations on network. On the practical plan, this work marks the arrival to maturity of relevant numeric methods for the study of the strong interactions.
It should play a fundamental role in the new era of the physics, which opens with Large Hadron Collider (LHC). Indeed, to check the model of the strong interactions could allow to bring to light new effects bound to the weak interactions of quarks which are masked by the strong interactions.
This calculation turns out one of the most important numeral calculations made to this day. A real performance which required the resources of the supercomputers Blue Gene of the Institute of the development and the resources in scientific computing (IDRIS) of the NATIONAL CENTRE FOR SCIENTIFIC RESEARCH and the Forschungszentrum Jülich, but also the farms of calculation of the University of Wuppertal and the Center of theoretical physical appearance of Marseille.

Image: The nuclei of atoms are constituted of protons and neutrons. Around these nuclei, electrons revolve. These three components (protons, neutrons and electrons) are virtually all matter. While the electron is considered as a particle "no size", the proton, which is composed of quarks, is an object "stretched".

 proton et quark


Classification  Particle composite (baryon)
Composition  2 quarks u, 1 quark d
Family  Fermion
Group  Quark
Interactions Strong, electromagnetic, weak, gravitation
Symbol  p, p+
Antiparticle  Antiproton

NB: The value of the proton radius used by physicists was 0.877 femtometer (a femtometer = 10-15 meter).

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