Taking a closer look at LHC

Particle responds to a force due to the presence of another particle because both two have thesame kind of charge.

This charge is a quantity carried by particles that determines their participation in an interactions process. A particle with electric charge has electrical interactions; one withstrong charge (or color charge) has strong interactions, one with weak charge (isospin or hypercharge) has weak interaction and inertial charge (mass) determines gravitational interaction.

One consequence of Heisenberg's uncertainty principle is that the energy and duration of a particle are also characterized by complementary uncertainties. There is always, at every point in space and time, even in a perfect vacuum, an uncertainty in energy and an uncertainty in duration, and these two complementary uncertainties cannot be reduced to zero simultaneously.

ΔE·Δt ~ ℏ  ΔE~ ℏ/Δt  Δm·c2~ ℏ/Δt

Δm ~ ℏ/(Δt·c2  (1)

A particle with mass = Δm can exist if its duration is less than Δt .


The meaning of Heisenberg's uncertainty principle is that "something" can arise from "nothing" if the "something" returns to the "nothing" after a very short time—an interval too short in which to be observed. These micro-violations of energy conservation are not only allowed to happen,they do, and so "empty" space is seething with particle-antiparticle pairs that come into being and then annihilate each other again after a very short interval.
The figure shows an interaction beetwen two electrons "using" a virtual photon (Feynman diagram).
Although these particles -VIRTUAL PARTICLES- cannot be observed individually , their existence can be demonstrated.


According (1), the more energy  virtual particle ‘borrows’ from de vacuum (so the more mass they have) the shorter the time they can exist.

For each interaction there is a carrier particle (fundamental boson) associated with quantum excitations of the force field corresponding to that interaction. They are virtual particles that form out of vacuum field, as it was said above.

Because photon and graviton are massless the electromagnetic and gravitational interaction can reache infinite distance. However, the big masa of carrier particles for weak interaction implies very short duration and very short distance. The case of strong interaction is differentand it's related to the special characterisitics of the strong charge.

Gluons are carrier particles for strong interactions (color force fields), photons are carrier particles of electromagnetic interactions,  the W and Z bosons are carrier particles for weak interactions, and gravitons are proposed as carrier particle for gravitational interaction.

The next animation shows a muon decay through a virtual W


Xabier Cid Vidal, PhD in experimental Particle Physics for Santiago University (USC). Research Fellow in experimental Particle Physics at CERN from January 2013 to Decembre 2015. Currently, he is in USC Particle Physics Department ("Ramon y Cajal", Spanish Postdoctoral Senior Grants).

Ramon Cid Manzano, secondary school Physics Teacher at IES de SAR (Santiago - Spain), and part-time Lecturer (Profesor Asociado) in Faculty of Education at the University of Santiago (Spain), until his retirement in 2020. He has a Degree in Physics and in Chemistry, and is PhD for Santiago University (USC).



CERN Directory

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CERN and the Environment



Detector CMS

Detector ATLAS

Detector ALICE

Detector LHCb

Detector TOTEM

Detector LHCf

Detector MoEDAL



 For the bibliography used when writing this Section please go to the References Section

© Xabier Cid Vidal & Ramon Cid -  | SANTIAGO (SPAIN) |