International Physics Masterclasses

New Physics

By colliding protons at higher energies and higher collision rates the LHC continues the exciting voyage towards new physics, allowing physicists all over the world to explore a previously unexplored territory full of promise.

As part of the search for new physics phenomena at the LHC, we have introduced the Z' boson. This particle is a heavy partner of the Z boson and is predicted by some theories beyond the Standard Model (SM) that require the introduction of a new weak force.

Let us concentrate on two of the greatest enigmas in physics today: the nature of dark matter (DM) and the behaviour of Gravity at the microscopic quantum scale.

Astronomical observations based on gravitational effects tell us that 85 per cent of the matter in the universe is dark, and normal matter (atoms made of electrons, and up- and down-quarks) only contributes to 5% of the content of the universe. Popular DM particle candidates are so-called weakly interacting massive particles, WIMPs for short. WIMP candidates are expected in supersymmetry, the most popular extension of the SM.

In analogy with other forces of nature, the force of gravity is carried by the hypothetical graviton, which has not yet been observed. While no satisfactory quantum description of gravity exists, superstring theories elegantly propose to incorporate gravity into the theoretical framework. The notion of a particle is replaced by extended objects - strings - living in 10 or 11 space-time dimensions, thus requiring 6 or 7 extra space dimensions.

Are there more space dimensions than the usual known 3, which would allow gravity-related phenomena, such as microscopic black holes and gravitons, to be discovered in the LHC era?

If accessible, the new phenomena above could be observed and studied by the ATLAS and CMS experiments at the LHC.