Fundamental or Composite? The Higgs Enigma

TL;DR

The paper discusses the significance of the Higgs boson discovery, exploring whether it is fundamental or composite, and emphasizes the importance of future colliders in resolving this question.

Contribution

It highlights the role of string phenomenology models in understanding the Higgs nature and proposes a future collider to investigate its fundamental or composite character.

Findings

Higgs properties can shed light on fundamental theories.

Composite Higgs would challenge existing string model work.

A 50-60 TeV collider could decisively determine Higgs nature.

Abstract

The discovery of the Higgs boson by the ATLAS and CMS experiments concluded a glorious century of experimental particle physics discoveries, from Rutherford's discovery of the nucleus in 1911, through the discoveries of quarks and leptons from the 1950s to the 1970s, to the discoveries of the weak vector bosons in the 1980s. It cemented the Standard Model of particle physics as providing the viable parameterisation of all sub-atomic observables up to the TeV scale and possibly up to the GUT and Planck scales. The experimental determination of the Higgs properties and parameters will shed light on these fundamental theories. A particularly pertaining question from the point of view of String Phenomenology is whether the Higgs boson is a fundamental or composite particle. The fermionic Z2xZ2 orbifolds provide bench mark models to explore how the parameters of the Standard Model can arise from a theory of quantum gravity, as well as for physics Beyond the Standard Model. Observation that the Higgs is composite will nullify much of the work that have gone into heterotic string model building over the past 40 years and will indicate the relevance of other classes of string vacua or possibly other approaches to quantum gravity. An ideal facility in the near future to investigate this question is a hadron collider at 50-60 TeV that utilises contemporary magnet technology and can be built in 10-15 years from decision.