Brane Induced Gravity, its Ghost and the Cosmological Constant Problem

摘要: "Brane Induced Gravity" is regarded as a promising framework for addressing the cosmological constant problem, but it also suffers from ghost instability parameter values that make phenomenologically viable. We carry out detailed analysis of codimension > 2 models employing gauge invariant variables in flat background approximation. It argued using instead curved sourced by brane would not resolve issue, unless very specific condition satisfied (if satisfiable at all). As other properties model, an explicit 4-dimensional graviton propagator we extract mass, decay width and momentum dependent modification gravitational coupling spin mode. In space approximation, mass problematic 0 instrumental filtering constant. The replaces curvature have had same function. optical theorem used to demonstrate suppression leakage into uncompactified bulk. Then, derive effective action gravity show general covariance spontaneously broken bulk-brane setup. This provides natural realization Higgs mechanism. addition extrinsic terms has no bearing on linearized gravity.