Graviton plus vector boson production to NLO in QCD at the LHC

We present the next-to-leading order QCD corrections to the associated production of the vector gauge boson (Z/W^±$Z/W^{\pm }$) and the graviton in the large extra dimension model at the LHC. We estimate the impact of the QCD corrections on the total cross sections as well as the differential distributions of the gauge bosons and find that they are significant. We also study the dependence of the cross sections on the arbitrary factorization scale and show the reduction in the scale uncertainties at NLO level. Further, we discuss the ultraviolet sensitivity of the theoretical predictions.     

Graviton dominance in quantum Kaluza-Klein theory

We compute, at the one-loop level, the effective potential for pure gravity in a Kaluza-Klein background geometry which is the direct product of four-dimensional Minkowski spacetime M⁴ with the N-sphere S^N, N odd. The computation is performed in the physical Lorentz-signature spacetime, avoiding the difficulties of “euclideanization”. We find that the contribution of each gravitational degree of freedom to the O(?) part of the effective potential is significantly greater than that of a scalar or spinor in the same background geometry. No stable minima of the effective potential exist for 3 ≤ N ≤ 13. Geometries which may be interpreted as “unstable solutions” are found for all N from 3 through 13. These results, obtained in Lorentz-signature spacetimes, differ from those obtained by “euclideanization”; our “euclideanized” results agree with those obtained by Chodos and Myers using a different regularization scheme.     

Graviton viscosity in the early universe

Second viscosity can have important effects in early stages of cosmological models. Here it is shown that nonlinear processes involving gravitons in the early universe might have given rise to such a viscosity.     

Nondiagonal seed universes and a network of double gravitational soliton universes

By using the double Ehlers transformations and transformations, new non-diagonal seed solutions are obtained. From these seed solutions we obtain a network of double gravitational soliton solutions. The double gravitational inverse scattering method is used to give some concrete examples of new solutions.     

Graviton and topology contributions to self-consistent cosmology

We study the graviton contribution and the topological effects of antipodal identification in constant curvature solutions of semiclassical Einstein equations. We analyze the curvature R as a function of the cosmological constant Γ, of the topology (labelled here by a discrete parameter σ), and of the trace anomaly λ, the mass m and the coupling ξ of quantum matter fields. For m=0, we find eight possible (some of them classically forbidden) configurations depending on the graviton-matter balance. Even if Γ>0, R can be negative and even if Γ≠0, R goes to zero when N (the number of matter fields) goes to infinity. For m≠0 we find five characteristic types of behaviours depending on the values of ξ and σ. The “back-reaction” effects of the topology appear more important for small ξ and increasing R.     

Geodesics in open universes

We present the geodesics on homogeneous and isotropic negatively curved spaces in a simple form suitable for application to cosmological problems. The pattern of geodesics translates into a pattern on the microwave background radiation. Generalizing, we discuss how the patterns in the microwave sky of anisotropic homogeneous universes can be predicted qualitatively by looking at the invariances that generate their three-geometries and their geodesics.     

Anisotropic universes and inflation

Some recent treatment of inflation in anisotropic universes is reviewed and we introduce results related toSO(3) Higgs fields and their influence on the violation of local isotropy.Presented at the International Conference Selected Topics in Quantum Field Theory and Mathematical Physics, Bechyn, Czechoslovakia, June 23–27, 1986.On leave of absence fromU.F.R.J., Inst. de Física, 21940, Rio de Janeiro, Brazil.Working for a Ph. D. degree.     

Graviton scattering amplitude in Bose string theory

The author derives a representation of the scattering amplitude of N gravitons in the form of an integral over surfaces in Bose string theory.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 17–20, December, 1988.     

Topological defects in contracting universes

We study the behavior and consequences of cosmic string networks in contracting universes. They approximately behave during the collapse phase as radiation fluids. Scaling solutions describing this are derived and tested against high-resolution numerical simulations. A string network in a contracting universe, together with the gravitational radiation it generates, can affect the dynamics of the universe both locally and globally and be an important source of radiation, entropy, and inhomogeneity. We discuss possible implications for bouncing and cyclic models.     

Boundary conditions in closed universes

We consider the problem of a particle in a square potential well in a one-dimensional closed universe. Imposition of periodic boundary conditions on the wave function changes the usual discrete energy levels to narrow but finite energy bands. Effects on the properties of atoms in a closed universe are estimated to be undetectable.     

Preferred frames and oscillating universes

A metric theory of gravitation is presented. It is based on the existence of a preferred ‘cosmic’ time. It agrees with all present experimental facts regarding gravitation and leads to singularity-free oscillating universes.     

On the energy-momentum in closed universes

Using the Moller, Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum definitions both in general relativity and teleparallel gravity, we find the energy-momentum of the closed universe based on the generalized Bianchi-I type metric.     

Shear Hell Holes and anisotropic universes

If the early universe was highly anisotropic, primordial black holes may have formed prolifically (despite previous claims to the contrary) even if the initial density fluctuations were small. However, the holes would initially be endowed with an immense amount of shear, so it is not obvious that they would evolve into the conventional type ofstationary black hole envisaged by the no hair theorem. If they do settle down to a stationary state, it may only be on a considerable time scale; and in principle there might exist soliton-type solutions which represent holes with shear which persists indefinitely. Such shear hell holes, as we term them, could have even more dramatic properties than the usual stationary holes: in particular, they might be prolific generators of gravitational radiation and they could be associated with interesting quantum effects.This essay received the fifth award from the Gravity Research Foundation for the year 1979-Ed.