PROBING VECTORLIKE FAMILIES IN ESSM/SO(10) THROUGH NEUTRINO COUNTING, HIGGS MASS AND ν–N SCATTERING

Abstract

The Extended Supersymmetric Standard Model (ESSM), motivated on several grounds, introduces two vectorlike families [[Formula: see text] of SO (10)] with masses of order 1 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 Vcb ≈ 0.04, and sin 2 2θνμντ ≈ 1. Extension of this framework to ESSM, preserving the successes of pattern I, has recently been proposed, where it was noted that ESSM can provide a simple explanation of a possible anomaly in (g-2)μ. To exhibit 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. We first note that either one of these two patterns, embedded in ESSM, would lead to a reduction in the LEP neutrino-counting from Nν = 3 (in good agreement with the data) and also provide a simple explanation of a possible (g-2)μ-anomaly. They can, however, be distinguished from each other by (a) a sharpening of our understanding of the true magnitude of the anomaly in νμ-nucleon scattering recently reported by the NuTeV group, (b) improved measurements of mt, mH and mW, (c) improved tests of e–μ lepton-universality in charged current processes, and (d) improvements in the measurements of Vud and Vus. Both patterns would predict some departure from the SM as regards tau lifetime. The probes listed above, and, of course, direct searches for the vectorlike families at the LHC and a future NLC can clearly test ESSM, and even distinguish between certain variants.