Bs0-B-bars0 mixing in leptophobic Z' model

Leptophobic Z' gauge boson appears naturally in many grand unified theories, such as flipped SU(5) or string-inspired E6 models. This elusive particle easily escapes the direct/indirect detections because it does not couple to charged leptons. However, it can generate flavor changing neutral current at tree level. In this Letter, we show that the recently measured mass difference, Δms, in the Bs0-B-bars0 system improves the previous bound of flavor changing effective coupling by about one order of magnitude, i.e. irrespective of its phase, vertical bar UsbZ' vertical bar=<0.036 for MZ'=700 GeV, and vertical bar UsbZ'vertical bar=<0.051 for MZ'=1 TeV