Searching for familynumber conserving neutral gauge bosons from extra dimensions.pdfVIP

Pis’ma v ZhETF Searching for family-number conserving neutral gauge bosons from extra dimensions + ∗ ∗1) ∗ J.M. Fr`ere , M.V. Libanov , E.Ya. Nugaev , S.V. Troitsky + Service de Physique Th´eorique, CP 225, Universit´e Libre de Bruxelles, B–1050, Brussels, Belgium; ∗ Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect 7a, Moscow 117312 Russia 4 Previous studies have shown how the three generations of the Standard Model fermions can arise from a 0 single generation in more than four dimensions, and how off-diagonal neutral couplings arise for gauge-boson 0 Kaluza-Klein recurrences. These couplings conserve family number in the leading approximation. While an 2 existing example, built on a spherical geometry, suggests a high compactification scale, we conjecture that the r overall structure is generic, and work out possible signatures at colliders, compatible with rare decays data. p A PACS: 12.60.-i, 13.85.-t 3 2 1. INTRODUCTION. 2. DISTINCTIVE FEATURES OF 2 ”SINGLE-GENERATION” v One reason to invoke more than four space-time di- EXTRA-DIMENSIONAL MODELS 9 mensions is to obtain elegant solutions for several long- 3 standing problems of particle physics [1] (see Ref. [2] 1 4 for a review). In particular, in the frameworks of “large If our four-dimensional world is nothing but a core of 0 extra dimensions”, models have been suggested [3, 4] a topological defect in (4 + D) dimensions, then spec