126 GeV Higgs and ATLAS bound on the lightest graviton mass in Randall-Sundrum model

In the search for extra dimension through dilepton events in 7-TeV proton-proton collision, the ATLAS detector at LHC has set stringent lower bound on the mass of the Randall-Sundrum (RS) lightest graviton Kaluza-Klein (KK) mode. Considering that the Randall-Sundrum model undertakes to resolve the well-known gauge hierarchy/fine tuning problem to restrict the Higgs mass within the estimated $\sim 126$ GeV against large radiative correction upto the cut-off of the model, we explore the allowed parameter space within which the RS model can be trusted. We show that the consistency of the model with ATLAS results constrains the cut-off of the theory which is atleast two order lower than the Planck/Quantum gravity scale implying the possible existence of a new Physics at this lower scale.Comment: 6 pages, 2 figures, 3 table

Lightest Kaluza-Klein graviton mode in a backreacted Randall-Sundrum scenario

In search of extra dimensions in the ongoing LHC experiments, signatures of Randall-Sundrum (RS) lightest KK graviton have been one of the main focus in recent years. The recent data from the dilepton decay channel at the LHC has determined the experimental lower bound on the mass of the RS lightest Kaluza-Klein (KK) graviton for different choices of underlying parameters of the theory. In this work we explore the effects of the backreaction of the bulk scalar field, which is employed to stabilise the RS model, in modifying the couplings of the lightest KK graviton with the standard model (SM) matter fields located on the visible brane. In such a modified background geometry we show that the coupling of the lightest KK graviton with the SM matter fields gets a significant suppression due to the inclusion of the backreaction of the bulk stabilising scalar field. This implies that the backreaction parameter weakens the signals from RS scenario in collider experiments which in turn explains the non-visibility of KK graviton in colliders. Thus we show that the modulus stabilisation plays a crucial role in the search of warped extra dimensions in collider experiments.Comment: 12 pages, 1 figur

Antisymmetric tensor fields in a generalized Randall-Sundrum scenario

Bulk antisymmetric tensor fields of different ranks have been studied in the context of a generalized Randall-Sundrum model with a non-vanishing induced cosmological constant on the visible brane. It is shown that instead of the usual exponential suppression of the couplings of the zero modes of these bulk fields with the brane fermions in the original Randal-Sundrum model, here the couplings are proportional to the brane cosmological constant. Thus in an era of large cosmological constant these fields have significant role in physical phenomena because of their enhanced couplings with the visible brane fermions.Comment: 14 Pages, 1 figure, Revte

Bouncing cosmology from warped extra dimensional scenario

From the perspective of four dimensional effective theory on a two brane warped geometry model, we examine the possibility of "bouncing phenomena"on our visible brane. Our results reveal that the presence of warped extra dimension lead to a non-singular bounce on the brane scale factor and hence can remove the "big-bang singularity". We also examine the possible parametric regions for which this bouncing is possible.Comment: 7 pages, 3 figure

Radion stabilization in higher curvature warped spacetime

We consider a five dimensional AdS spacetime in presence of higher curvature term like $F(R) = R + \alpha R^2$ in the bulk. In this model, we examine the possibility of modulus stabilization from the scalar degrees of freedom of higher curvature gravity free of ghosts. Our result reveals that the model stabilizes itself and the mechanism of modulus stabilization can be argued from a geometric point of view. We determine the region of the parametric space for which the modulus (or radion) can to be stabilized. We also show how the mass and coupling parameters of radion field are modified due to higher curvature term leading to modifications of its phenomenological implications on the visible 3-brane.Comment: 11 pages, 1 figur

Graviton modes in multiply warped geometry

The negative results in the search for Kaluza-Klein graviton modes at the LHC, when confronted with the discovery of the Higgs, has been construed to have severely limited the efficacy of the Randall-Sundrum model as an explanation of the hierarchy problem. We show, though, that the presence of multiple warping offers a natural resolution of this conundrum through modifications in both the graviton spectrum and their couplings to the Standard Model fields.Comment: 16 pages, 6 figure