Locally Localized Gravity Models in Higher Dimensions

We explore the possibility of generalizing the locally localized gravity model in five space-time dimensions to arbitrary higher dimensions. In a space-time with negative cosmological constant, there are essentially two kinds of higher-dimensional cousins which not only take an analytic form but also are free from the naked curvature singularity in a whole bulk space-time. One cousin is a trivial extension of five-dimensional model, while the other one is in essence in higher dimensions. One interesting observation is that in the latter model, only anti-de Sitter ($AdS_p$) brane is physically meaningful whereas de Sitter ($dS_p$) and Minkowski ($M_p$) branes are dismissed. Moreover, for $AdS_p$ brane in the latter model, we study the property of localization of various bulk fields on a single brane. In particular, it is shown that the presence of the brane cosmological constant enables bulk gauge field and massless fermions to confine to the brane only by a gravitational interaction. We find a novel relation between mass of brane gauge field and the brane cosmological constant.Comment: 20 pages, LaTex 2e, revised version (to appear in Phys. Rev. D

Nambu-Goto Strings from SU(N) Born-Infeld model

The spectrum of quenched Yang-Mills theory in the large-N limit displays strings and higher dimensional extended objects. The effective dynamics of string-like excitations is encoded into area preserving Schild action. In this letter, we bridge the gap between SU(N) gauge models and fully reparametrization invariant Nambu-Goto string models by introducing an extra matrix degree of freedom in the Yang-Mills action. In the large-N limit this matrix variable becomes the world-sheet auxiliary field allowing a smooth transition between the Schild and Nambu-Goto strings. The new improved matrix model we propose here can be extended to p-branes provided we enlarge the dimensionality of the target spacetime.Comment: 11pages, no figures, LateX2e; added discussio

Renormalizability of Massive Gravity in Three Dimensions

We discuss renormalizability of a recently established, massive gravity theory with particular higher derivative terms in three space-time dimensions. It is shown that this massive gravity is certainly renormalizable as well as unitary, so it gives us a physically interesting toy model of perturbative quantum gravity in three dimensions.Comment: 13 pages, no figure

Bosonic Fields in the String-like Defect Model

We study localization of bosonic bulk fields on a string-like defect with codimension 2 in a general space-time dimension in detail. We show that in cases of spin 0 scalar and spin 1 vector fields there are an infinite number of massless Kaluza-Klein (KK) states which are degenerate with respect to the radial quantum number, but only the massless zero mode state among them is coupled to fermion on the string-like defect. It is also commented on interesting extensions of the model at hand to various directions such as 'little' superstring theory, conformal field theory and a supersymmetric construction.Comment: 17 pages, LaTex 2e, revised version (to appear in Phys. Rev. D

Warped Compactification with an Abelian Gauge Theory

We investigate warped compactification with an abelian gauge theory in six dimensions. The vanishing cosmological constant in four dimensions can generically be realized with a regular metric even in a 3-brane background without fine tuning of couplings.Comment: 6 pages, late

Synthesis, structure and some reactions of a multi-bridged unsaturated cyclooctadecane derivative formally having two cycloheptatrienes

ArticleTETRAHEDRON LETTERS. 48(33): 5811-5815 (2007)journal articl

Massive Gravity in Curved Cosmological Backgrounds

We study the physical propagating modes in a massive gravity model in curved cosmological backgrounds, which we have found as classical solutions in our previous paper. We show that, generically, there exist such the cosmological background solutions consistent with the equations of motion where we assume the ghost condensation ansatzes. Using the (1+3)-parametrization of the metric fluctuations with 'unitary' gauge, we find that there is neither a scalar ghost nor a tachyon in the spectrum of the propagating modes, the tensor modes become massive owing to gravitational Higgs mechanism, and the model is free of the Boulware-Deser instability. The price we have to pay is that the scalar sector breaks the Lorentz-invariance, but there are no pathologies in the spectrum and lead to interesting phenomenology. Moreover, we present a proof of the absence of non-unitary modes for a specific ghost condensation model in a cosmological background.Comment: 20 page

Heavy Higgs at Tevatron and LHC in Universal Extra Dimension Models

Universal Extra Dimension (UED) models tend to favor a distinctively heavier Higgs mass than in the Standard Model (SM) and its supersymmetric extensions when the Kaluza-Klein (KK) scale is not much higher than the electroweak one, which we call the weak scale UED, in order to cancel the KK top contributions to the T-parameter. Such a heavy Higgs, whose production through the gluon fusion process is enhanced by the KK top loops, is fairly model independent prediction of the weak scale UED models regardless of the brane-localized mass structure at the ultraviolet cutoff scale. We study its cleanest possible signature, the Higgs decay into a Z boson pair and subsequently into four electrons and/or muons, in which all the four-momenta of the final states can be measured and both the Z boson masses can be checked. We show that the weak scale UED model may account for the 2sigma excess of this event at ATLAS at the ZZ pair invariant mass around 250GeV, at which scale SM background is sufficiently small and the SM Higgs predicts too few events. We have also studied the Higgs mass 500GeV (and also 700GeV with \sqrt{s}=14TeV) and have found that we can observe significant resonance with the integrated luminosity 10fb^{-1} for six dimensional UED models.Comment: (v1) 36 pages, 9 figures, 6 tables; (v2) Accepted for publication in Phys. Rev. D, factor 2 error in (93) corrected, comments and references added, figures redrawn; (v3) Minor changes including typo corrections in eq.(15), final version appearing in PR