Τ Polarization and Randall-sundrum Scenario at E

We study polarized cross-sections and forward-backward asymmetry for the process e+e− → τ+τ− in the stabilized Randall-Sundrum scenario. It is shown that there is substantial deviation from the Standard Model predictions, both in terms of the actual numerical values and angular distributions. The hierarchy between the electroweak and the Planck scale remains to be a mystry till date. Many possible solutions have been proposed. The idea that the fundamental scale of gravity is not as large as the Planck scale, O(10−19 GeV), but could be as low as O(TeV) has invited considerable attention. The basic idea behind such a proposal [1] is the existence of n compact extra spatial dimensions. The Standard Model (SM) fields all lie on a 3-brane while gravity is free to propagate in the entire bulk. The four dimensional Planck scale, MP l, gets related to the fundamental scale of gravity, M∗, and the volume, Vn, of the n extra dimensions as M P l ∼ VnM ∗ (1) In this picture the bulk space-time is a direct product of the four-dimenisoal Minkowski space and the extra dimensions. To attain the relevant numbers, the volume Vn should be large and this in turn introduces a new hierarchy between the electroweak scale and the inverse of the size of these extra dimensions. An alternative scenario due to Randall and Sundrum [2] assumes the existence of two 3-branes which define the ends of the world in the context of a five dimensional bulk space-time. The bulk geometry in this case, in contrast to the previous one, is nonfactorizable and the hierarchy is generated by the warp factor which is an exponential function of the inter-brane distance. The same warp factor relates the induced metrics on the two branes. The question of stability of this inter-brane distance still remains an important issue of concern. It was shown by Goldberger and Wise [3] that the inclusion of a bulk scalar field minimally coupled to gravity does indeed admit a stable solution. ∗E–mail : [email protected], [email protected]