Constraining Large Extra Dimensions Using Dilepton Data from the Tevatron Collider.pdf

a r X i v : h e p - p h / 9 9 0 4 2 3 4 v 1 5 A p r 1 9 9 9 TIFR-HECR-99-02 hep-ph/9904234 Constraining Large Extra Dimensions Using Dilepton Data from the Tevatron Collider Ambreesh K. Gupta 1, Naba K. Mondal 2, Sreerup Raychaudhuri 3 ’ 4 Department of High Energy Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India. Abstract We use the invariant mass distribution of Drell-Yan dileptons as measured by the CDF and D? Collaborations at the Fermilab Tevatron and make a careful analysis to constrain Kaluza-Klein models with large extra dimensions. The combined data from both collaborations lead to a conservative lower bound on the string scale MS of about 1 TeV at 95% confidence level. April 1999 1E-mail: ambr@tifr.res.in 2E-mail: nkm@tifr.res.in 3E-mail: sreerup@iris.hecr.tifr.res.in 4 Address after May 1, 1999: Department of Physics, Indian Institute of Technology, Kanpur 208 016, India. Recently, the idea that gravity could become strong at scales of the order of a few TeV has attracted a great deal of attention[1]. This is made possible if we allow for large compactified dimensions at the TeV scale. While such ideas can be fitted in within the scheme of quantum field theories[2], a more natural construction[3, 4] involves string theories with all Standard Model (SM) fields living on a three-dimensional D-brane (or 3-brane) embedded in a space of (4+d) dimensions (bulk). Of course, the original suggestion that we live in a spacetime continuum with more than the three canonical spatial dimensions was made early in this century [5], but these Kaluza-Klein (KK) theories, as they are called, have not been able to satisfactorily reproduce the observed mass spectrum. Such ideas, however, have always formed a basic ingredient of string theories[6]. In fact, models having extra dimensions with compactification scales of the order of a few TeV have been proposed[7] from time to time in the literature with various motivations.