The Krein-Gupta-Bleuler Quantization in de Sitter Space-time; Casimir Energy-Momentum Tensor for a Curved Brane

In this paper, vacuum expectation value (VEV) of the energy-momentum tensor for a conformally coupled scalar field in de Sitter space-time is investigated through the Krein-Gupta-Bleuler construction. This construction has already been successfully applied to the de Sitter minimally coupled massless scalar field and massless spin-2 field to obtain a causal and fully covariant quantum field on the de Sitter background. We also consider the effects of boundary conditions. In this respect, Casimir energy-momentum tensor induced by Dirichlet boundary condition on a curved brane is evaluated.Comment: 9 page

A Group Theoretical Approach to Graviton Two-Point Function

Respecting the group theoretical approach, it is debated that the theory of linear conformal gravity should be formulated through a tensor field of rank-3 and mixed symmetry \cite{binegar}. Pursuing this path, such a field equation was obtained in de Sitter space \cite{takook}. In present work, considering the de Sitter ambient space notation, a proper solution to the physical part of this field equation is obtained. We have also calculated the related two-point function, which is interestingly de Sitter invariant and free of infrared divergence.Comment: 10 page

A small non-vanishing cosmological constant from the Krein-Gupta-Bleuler vacuum

We point out a potential relevance between the Krein-Gupta-Bleuler (KGB) vacuum leading to a fully covariant quantum field theory for gravity in de Sitter (dS) spacetime and the observable smallness of the cosmological constant. This may provide a formulation of linear quantum gravity in a framework amenable to developing a more complete theory determining the value of the cosmological constant.Comment: 3 page

A fibrinolytic acid proteinase in human plasma

An attempt has been made to purify an acid proteinase from human plasma, which is capable of dissolving fibrin clot in 1% (w/v) monochloroacetic acid. On SDS gel electrophoresis the enzyme isolated from plasma contains two protein bands with molecular weights of approximately 90,000 and 54,000. Different substrates were used to evaluate the proteolytic activity of the plasma enzyme, including fibrin clot, azo-casein, acid denatured haemoglobin (Hb), haemoglobin polyacrylamide gel (insoluble Hb), haemoglobin electrophoresis (soluble Hb) and the synthetic substrate N-acetyl-L-phenylalanyl-L-diiodotyrosine. The plasma enzyme seems to belong to the group of aspartyl proteinases as its activity against the above substrates was maximal at low pH, and was inhibited by pepstatin which is a powerful inhibitor of aspartyl proteinases

Covariant Quantization of the Partially Massless Graviton Field in de Sitter Spacetime

We present a covariant quantization scheme for the so-called ``partially massless" graviton field in de Sitter spacetime. Our approach is founded on the principles of the de Sitter group representation theory (in the sense given by Wigner), the Wightman-G\"{a}rding axioms for gauge-invariant fields (Gupta-Bleuler scheme), and the essential analyticity prerequisites in the complexified pseudo-Riemannian manifold. To implement the quantization process effectively, we adopt coordinate-independent (global) de Sitter plane waves. These plane waves, defined in the appropriate tube domains of complex de Sitter spacetime, serve as the de Sitter counterparts to the standard Minkowskian plane waves. By employing these analytical plane waves, we enable a spectral analysis of the corresponding two-point function that closely resembles the Fourier analysis typically employed in the flat Minkowskian case. Within this framework, we present the Wightman two-point function for the partially massless graviton field, which satisfies the essential criteria of locality, covariance, and normal analyticity. Furthermore, we provide insights into the underlying Hilbert space structure and the corresponding unsmeared field operator. A direct consequence of this quantization construction confirms the widely accepted notion of light-cone propagation for the de Sitter partially massless graviton field.Comment: 22 pages, no figur