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Can the Large Hadron Collider detect evidence for string theory?

In string theory the fundamental objects in the universe are tiny strings and branes. Although too small to see directly, the most powerful subatomic colliders might detect indications of them.
Can the Large Hadron Collider detect evidence for string theory?
The Large Hadron Collider (LHC) is the most powerful collider available. The STRINGPHENOATLHC (String phenomenology at the era of LHC) project considered several ways that the LHC might detect the existence of strings.

A detailed analysis was made of the scattering amplitude containing light stringy states. The amplitudes calculated establish experimental signatures for light stringy states that can be tested at the LHC. The studies were extended to include higher spin fields. Again, they establish experimental signatures that can be tested at the LHC and also give insight into couplings of higher spin fields to other string states.

The project investigated the presence of Abelian discrete symmetries in the context of semi-realistic globally consistent Gepner models.

Team members generalised their search by allowing the discrete symmetry to partially originate from the hidden sector. Allowing for this generalisation they found that discrete symmetries are quite typical in Gepner models. Moreover, they found that some specific constructions exhibit Baryon triality, thus giving a natural explanation for the absence of dimension 5 proton decay operators.

A follow-up effort extended the search to other Gepner constructions, looking for matter parity and proton triality. The aim was also to identify what features a Gepner construction has to satisfy in order to give a specific type of discrete symmetry. No simple mapping was found.

As part of a programme to explore D-brane model building and D-instantons, the project looked at phenomenological aspects of typical semi-realistic type II/ F-theory constructions. These involve the string theory prediction of supersymmetry (SUSY) partners for the well-known standard model particles like electrons and quarks. Specifically, they studied the general patterns of SUSY-breaking soft terms that arise in typical type II SUSY-breaking scenarios.

The plan was to determine some typical signatures that are potentially observable at the next run of the LHC.

In a study of moduli stabilisation and de Sitter vacuum, no stable minima leading to a positive cosmological constant was found. The team has proposed a mechanism to sequester the standard model vacuum contributions to the cosmological constant. It investigated the consequences of embedding this proposal into a fully local quantum field theory. The resulting Lagrangian is that of a spontaneously broken conformal field theory, indicating that the proposal has an underlying conformal field theory structure.

Related information

Keywords

Large Hadron Collider, string theory, branes, STRINGPHENOATLHC, Lagrangian
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