NuTeV anomaly, neutrino mixing, and a heavy Higgs boson

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American Physical Society

Recent results from the NuTeV experiment at Fermilab and the deviation of the Z invisible width, measured at CERN LEP and the SLAC Linear Collider, from its standard model (SM) prediction suggest the suppression of neutrino-Z couplings. Such suppressions occur naturally in models which mix the neutrinos with heavy gauge singlet states. We postulate a universal suppression of the Znunu couplings by a factor of (1-epsilon) and perform a fit to the Z-pole and NuTeV observables with epsilon and the oblique correction parameters S and T. Compared to a fit with S and T only, the inclusion of epsilon leads to a dramatic improvement in the quality of the fit. The values of S and T preferred by the fit can be obtained within the SM by a simple increase in the Higgs boson mass. However, if the W mass is also included in the fit, a non-zero U parameter becomes necessary which cannot be supplied within the SM. The preferred value of epsilon suggests that the seesaw mechanism may not be the reason why neutrinos are so light.

fermion pair production, supersymmetric standard model, extra, dimensions, sin(2) theta(w), qed corrections, mass, annihilation, oscillation, parameters, calculate, Astronomy & Astrophysics, Physics
Loinaz, W ; Okamura, N ; Takeuchi, T ; et al., APR 2003. “NuTeV anomaly, neutrino mixing, and a heavy Higgs boson,” PHYSICAL REVIEW D 67(7): 073012. DOI: 10.1103/PhysRevD.67.073012