Stringy origin of Tevatron Wjj anomaly |
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Authors: | Luis A Anchordoqui Haim GoldbergXing Huang Dieter Lüst Tomasz R Taylor |
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Institution: | a Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA b Department of Physics, Northeastern University, Boston, MA 02115, USA c Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München, Germany d Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, 80333 München, Germany e Physics Division (TH), CERN 1211, Geneva 23, Switzerland |
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Abstract: | The invariant mass distribution of dijets produced in association with W bosons, recently observed by the CDF Collaboration at Tevatron, reveals an excess in the dijet mass range 120-160 GeV/c2, 3σ beyond Standard Model expectations. We show that such an excess is a generic feature of low mass string theory, due to the production and decay of a leptophobic Z′, a singlet partner of SU(3) gluons coupled primarily to the U(1) baryon number. In this framework, U(1) and SU(3) appear as subgroups of U(3) associated with open strings ending on a stack of 3 D-branes. In addition, a minimal model contains two other stacks to accommodate the electro-weak SU(2)⊂U(2) and the hypercharge U(1). Of the three U(1) gauge bosons, the two heavy Z′ and Z″ receive masses through the Green-Schwarz mechanism. For a given Z′ mass, the model is quite constrained. Fine tuning three of its free parameters is just sufficient to simultaneously ensure: a small Z-Z′ mixing in accord with the stringent LEP data on the Z mass; very small (less than 1%) branching ratio into leptons; and a large hierarchy between Z″ and Z′ masses. The heavier neutral gauge boson Z″ is within the reach of LHC. |
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Keywords: | TeV-scale string D-brane compactifications |
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