Related papers: VSFT revisited
We present the most general covariant ghost-free gravitational action in a Minkowski vacuum. Apart from the much studied f(R) models, this includes a large class of non-local actions with improved UV behavior, which nevertheless recover…
Conformal transformations play a widespread role in gravity theories in regard to their cosmological and other implications. In the pure metric theory of gravity, conformal transformations change the frame to a new one wherein one obtains a…
In this lecture notes we explain and discuss some ideas concerning noncommutative geometry in general, as well as noncommutative field theories and string field theories. We consider noncommutative quantum field theories emphasizing an…
We suggest that the solution to the cosmological vacuum energy puzzle is linked to the infrared sector of the effective theory of gravity interacting with standard model fields, with QCD fields specifically. We work in the framework of low…
We offer some thoughts regarding the space of string fields. We suggest that this space should be identified as the odd component of a star-algebra and focus among other issues on the role of the mid-point. We argue that theories with…
A new representation is found for the action of the recently suggested ghost-free nonlocal gravity models generating de Sitter or Anti-de Sitter background with an arbitrary value of the effective cosmological constant. This representation…
We study quantum corrections at the one loop level in open superstring tachyon condensation using the boundary string field theory (BSFT) method. We find that the tachyon field action has the same form as at the disc level, but with a…
We reformulate bosonic boundary string field theory in terms of boundary state. In our formulation, we can formally perform the integration of target space equations of motion for arbitrary field configurations without assuming decoupling…
The general BRST-BFV analysis of anomaly in the string theory coupled to background fields is carried out. An exact equation for c-valued symbol of anomaly operator is found and structure of its solutions is studied.
We study string theory in supersymmetric time-dependent backgrounds. In the framework of general relativity, supersymmetry for spacetimes without flux implies the existence of a covariantly constant null vector, and a relatively simple form…
It is well-known that the standard no-ghost theorem can be extended straightforwardly to the general c=26 CFT on R^{d-1,1} \times K, where 2 \leq d \leq 26 and K is a compact unitary CFT of appropriate central charge. We prove the no-ghost…
We present the Y-formalism for the non-minimal pure spinor quantization of superstrings. In the framework of this formalism we compute, at the quantum level, the explicit form of the compound operators involved in the construction of the…
5D superconformal theories involve vacuum valleys characterized in the simplest case by the vacuum expectation value of a real scalar field. If it is nonzero, conformal invariance is spontaneously broken and the theory is not…
We propose a new BRST operator for the B-twist of $N=2$ Landau-Ginzburg (LG) models. It solves the problem of the fractional ghost numbers of Vafa's old BRST operator and shows how the model is obtained by gauge fixing a zero action. An…
We elucidate some exact relations between light-cone and covariant string field theories on the basis of the homological perturbation lemma for $A_{\infty }$. The covariant string field splits into the light-cone string field and trivial…
We study static cosmic string solutions in the context of Bekenstein-type models. We show that there is a class of models of this type for which the classical Nielsen-Olesen vortex is still a valid solution. However, in general static…
We present a detailed analysis of the cosmic string spectrum. Explicit solutions are numerically found using Mathematica and presented here for the lowest-lying supported modes. Most of the emphasis is on the Nambu-Goldstone modes and the…
An exact conformal model representing a constant magnetic field background in heterotic string theory is explicitly solved in terms of free creation/annihilation operators. The spectrum of physical states is examined for different possible…
We present a novel way to constrain the ghost field with respect to other physical fields present in a given theory such that the theory becomes quantizable. This is achieved by imposing positivity of the total kinetic energy of the system…
In this work we develop a theoretical framework for Gauss-Bonnet modified gravity theories, in which ghost modes can be eliminated at the equations of motion level. Particularly, after we present how the ghosts can occur at the level of…