Neutrino Counting, NuTeV Measurements, Higgs Mass and V_{us} as Probes of Vectorlike Families in ESSM/SO(10)

Abstract

The Extended Supersymmetric Standard Model (ESSM), motivated on several grounds, introduces two vector-like families [16+ 16-bar of SO(10)] with masses of order one TeV. In an earlier work, a successful pattern for fermion masses and mixings (to be called pattern I) has been proposed within a unified SO(10)-framework, based on MSSM, which makes seven predictions, in good accord with observations, including V_{cb} ~ 0.04, and \sin^22\theta_{\nu_\mu\nu_\tau} \~ 1. To exibit new phenomenological possibilities which may arise within ESSM, we present here a variant pattern (to be called pattern II) for fermion masses and mixings, within the SO(10)/ESSM framework, which possesses the same degree of success as pattern I as regards the masses and mixings of all fermions including neutrinos. The main point of this paper is to first note that either one of these two patterns, embedded in ESSM, would lead to a reduction in the LEP neutrino-counting from N_\nu = 3 (in good agreement with the data) and also provide a simple explanation of the (g-2)_\mu-anomaly, as pointed out in the accompanying paper. They can, however, be distinguished from each other by (a) a sharpening of our understanding of the true magnitude of the anomaly in \nu_\mu-nucleon scattering, recently reported by the NuTeV group, (b) improved measurements of m_t, m_H and m_W, (c) improved tests of e-\mu lepton-universality in charged current processes, and (d) improvements in the measurements of V_{ud} and V_{us}. Pattern II (extended to ESSM) would predict departures from the standard model in the right direction with regard to (a) and (b), though not as regards (c) and (d) while Pattern I practically would coincide with the standard model as regards its predictions for all four features: (a)-(d).