Higher Derivative Scalar Theory Research Articles

Cosmology of a higher derivative scalar theory with non-minimal Maxwell coupling

Higher derivative scalar field theory in curved space-time belongs to the GLPV theory coupled non-minimally to the Maxwell field is considered. We will show that the theory admits two independent exact de Sitter solutions in the FRW background, one driven by the cosmological constant and the other by the GLPV scalar field. The dynamical system analysis of the theory shows that these two exact solutions are stable fixed points. Also, cosmological perturbations over these solutions shows that the cosmological constant based solution is healthy at linear level but the GLPV based solution suffers from a gradient instability in the scalar sector. This proves that the cosmological constant is needed in the GLPV-Maxwell system in order to have a healthy de Sitter solution.

Reflection positivity in higher derivative scalar theories

Reflection positivity constitutes an integral prerequisite in the Osterwalder–Schrader reconstruction theorem which relates quantum field theories defined on Euclidean space to their Lorentzian signature counterparts. In this work, we rigorously prove the violation of reflection positivity in a large class of free scalar fields with a rational propagator. This covers, in particular, higher-derivative theories where the propagator admits a partial fraction decomposition as well as degenerate cases including, e.g., p4-type propagators.

Liouville conformal field theories in higher dimensions

We consider a generalization of the two-dimensional Liouville conformal field theory to any number of even dimensions. The theories consist of a log-correlated scalar field with a background mathcal{Q} -curvature charge and an exponential Liouville-type potential. The theories are non-unitary and conformally invariant. They localize semiclassically on solutions that describe manifolds with a constant negative mathcal{Q} -curvature. We show that CT is independent of the mathcal{Q} -curvature charge and is the same as that of a higher derivative scalar theory. We calculate the A-type Euler conformal anomaly of these theories. We study the correlation functions, derive an integral expression for them and calculate the three-point functions of light primary operators. The result is a higher-dimensional generalization of the two-dimensional DOZZ formula for the three-point function of such operators.

Renormalization of higher derivative scalar theory

We consider a lattice scalar field model with higher derivative terms in the action whose phase diagram contains a tricritical point which is also a triple point between the paramagnetic, ferromagnetic and antiferromagnetic phases. The continuum limit is defined by approching the tricritical point from the paramagnetic side. Contrary to the lattice tricritical g6ϕ6 model we can do a perturbative computation in dimension four. The non-perturbative aspect of the theory relies on the dispersion relation which has the particular feature of having several minima similar to the propagator of lattice fermions. It is shown that this new model is perturbatively renormalizable and provides a non trivial mass spectrum. The positive norm Hilbert space and the unitarity of the time evolution operator in Minkowski space is established by means of the reflection positivity property.