Inflation in string theory
Within the context of the FUSS (Flavor, unification and symmetries from strings) project, scientists made judicious use of effective field theory as a bottom-up tool and controlled approximations in string theory. This line of research indicated phenomena of the early universe cosmology that can be well described by certain classes of solutions. String theory contains all the necessary ingredients for particle physics, like gauge symmetries and chiral fermions. At small enough energies, string theory is reduced to an effective field theory. This theory contains gauge fields coupled to fermionic matter and a number of scalar fields, in addition to general relativity extended by a series of high-order curvature corrections. Without the presence of symmetries remaining unbroken, the phenomenon with the need of a description beyond effective field theory coupled to general relativity is cosmological inflation. The FUSS scientists’ efforts to develop theoretical models of large-field inflation were supported by high-precision data from the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck mission. Scientists proposed that the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM) extension of the Standard Model drove inflation. This idea was conceptually attractive since Higgs physics and cosmological inflation are intimately connected. Moreover, the required large field excursions of chaotic inflation could be realised in string theory with inflation and the Higgs potential. FUSS research proved fruitful, and its findings were shared with the scientific community in a series of publications in high-impact peer-reviewed journals. The impact was so significant that the project team was invited to give plenary talks at international conferences, including the prestigious ‘Strings’ held at the Princeton University in the USA.
Keywords
String theory, large-field inflation, FUSS, effective field theory, early universe, Standard Model
