The profile of the Higgs boson: status and prospects

Abstract

The Higgs boson, which was discovered at CERN in 2012, stands out as a remarkable elementary particle with distinct characteristics. Unlike any other observed particle, it possesses zero spin within the Standard Model (SM) of particle physics. Theoretical predictions had anticipated the existence of this scalar boson, postulating its interaction with the W and Z bosons as well as through Yukawa interactions with fermions. Furthermore, the Higgs boson can interact with itself, commonly referred to as the Higgs self-interaction. In this review, the current state of experimental and theoretical investigations of Higgs boson production at the Large Hadron Collider and the ongoing efforts to unravel its properties are described, and an up-to-date assessment of our understanding of the Higgs sector of the SM is provided. In addition, potential links between the Higgs boson and significant unresolved questions within the realm of particle physics are presented. This article is part of the theme issue ‘The particle-gravity frontier’.

The cosmological constant and scale hierarchies with emergent gauge symmetries

“…The Standard Model relations equations (2.1) and (2.2) have been tested to good precision about 10% for the W and Z gauge bosons, the heavy top and bottom quarks, and the τ and μ charged leptons. The measured coupling strengths scale as a function of the particle masses just as predicted by the Standard Model-see [4,9]. For RG evolution one also needs input on the Higgs self-coupling λ.…”

“…Taking v = 246 GeV and m h = 125 GeV gives λ = m 2 h /2v 2 ≈ 0.13 as input at LHC laboratory scales. Measurement of λ awaits future collider experiments with precision about 50% expected from the high luminosity upgrade of the LHC and 5% precision requiring a new 100 TeV higher energy collider [9].…”

“…Equation (3.5) is sometimes taken as phenomenological evidence to hint that usual Newtonian gravity might be modified, the so called MOND theories [121]. 9 It may also be the net result that should come out from simulating a microscopic theory of dark matter involving new dark matter particles within usual General Relativity and connected to galaxy formation. This issue is a step beyond the simple fit to data associated with equation (3.5).…”

“…The Standard Model is built on the local gauge symmetries of electroweak interactions and quantum chromodynamics, QCD, with the gauge groups U(1) Y , SU(2) L and SU(3) c . Beyond the spin (1/2) leptons and quarks plus spin-one gauge bosons, the Higgs boson with spin zero and mass 125 GeV discovered at CERN behaves in a very Standard Model-like way and completes the particle spectrum of the Standard Model [4,9]. General Relativity describes gravitation wherever it has been tested with recent highlights including the discovery of gravitational waves [10] and black hole imaging [11].…”

“…Today a vigorous programme of experiments and theory is probing the high energy and precision frontiers together with cosmology looking for cracks in our description of Nature provided by the Standard Model and General Relativity. Ideas for new physics are discussed in the parallel theoretical contributions to this volume [15][16][17] with experiments discussed in [9,[18][19][20][21][22].…”