Neutrino Masses, Leptogenesis, and Unification in the Absence of Low Energy Supersymmetry

We explore generating the dimension five operator leading to neutrino masses by integrating out heavy SU(2)_L triplet fermions. We exhibit a model that has a neutrino mass matrix consistent with observations. In addition, the model is capable of producing the observed baryon asymmetry, and unification can be achieved without dangerous proton decay. Supersymmetry can be broken at the fundamental scale with no supersymmetric signal at low energies.Comment: 26 pages, 3 figures, typos corrected and references added, published in JHE

Flux Tube Spectra from Approximate Integrability at Low Energies

We provide a detailed introduction to a method we recently proposed for calculating the spectrum of excitations of effective strings such as QCD flux tubes. The method relies on the approximate integrability of the low energy effective theory describing the flux tube excitations and is is based on the Thermodynamic Bethe Ansatz (TBA). The approximate integrability is a consequence of the Lorentz symmetry of QCD. For excited states the convergence of the TBA technique is significantly better than that of the traditional perturbative approach. We apply the new technique to the lattice spectra for fundamental flux tubes in gluodynamics in D=3+1 and D=2+1, and to k-strings in gluodynamics in D=2+1. We identify a massive pseudoscalar resonance on the world sheet of the confining strings in SU(3) gluodynamics in D=3+1, and massive scalar resonances on the world sheet of k=2,3 strings in SU(6) gluodynamics in D=2+1.Comment: 44 pages, 19 figures, v2: references added, to appear in special issue of JETP dedicated to Valery Rubakov's 60th birthda