New bound on right-handed charged gauge boson mass.
Using our previous bounds on [Delta][rho] and the [ital Z]-[ital Z][prime] mixing angle [xi][sub [ital N]] in the SU(2)[sub [ital L]][direct product]SU(2)[sub [ital R]][direct product]U(1)[sub ([ital B][minus][ital L])] model from the [ital Z] line shape and energy-dependent forward-backward asymmetries of the 1990 data from CERN LEP, we obtain a strong lower bound [congruent]439 GeV at 90% C.L. on the right-handed charged gauge boson mass for [ital m][sub [ital t]]=200 GeV using commonly chosen Higgs triplets, which becomes stronger for doublet Higgs fields. It is independent of the neutrino mass or of assumptions about the right-handed quark mixing matrix. Consequences of more exotic Higgs multiplets are also discussed.

title: Superunified model with naturally ultralight dirac neutrinos
abstract: The recently proposed mechanism to naturally generate one ultralight Dirac neutrino per fermion family is implemented by construction of a globally supersymmetric SO(10) GUT superpotential featuring geometric hierarchy. A step forward is thus taken towards providing a firm theoretical basis for the relation m ν = O (m 3 2 )M SUSY /M GUT .

title: Neutrino dark energy in grand unified theories
abstract: We studied a left-right symmetric model that can accommodate the neutrino dark energy (νDE) proposal. The type-III seesaw mechanism is implemented to give masses to the neutrinos. After explaining the model, we study the consistency of the model by minimizing the scalar potential and obtaining the conditions for the required vacuum expectation values of the different scalar fields. This model is then embedded in an SO(10) grand unified theory and the allowed symmetry breaking scales are determined by the condition of the gauge coupling unification. Although SU(2) R breaking is required to be high, its Abelian subgroup U(1) R is broken in the TeV range, which can then give the required neutrino masses and predicts new gauge bosons that could be detected at LHC. The neutrino masses are studied in detail in this model, which shows that at least 3 singlet fermions are required.

title: Degenerate Dirac neutrinos
abstract: A simple extension of the standard model is proposed in which all the three generations of neutrinos are Dirac particles and are naturally light. We then assume that the neutrino mass matrix is diagonal and degenerate, with a few eV mass to solve the dark matter problem. The self-energy radiative corrections, however, remove this degeneracy and allow mixing of these neutrinos. The electroweak radiative corrections then predict a lower bound on the ν μ -ν e mass difference which solves the solar neutrino problem through the MSW mechanism and also predict a lower bound on the ν τ -ν μ mass difference which is just enough to explain the atmospheric neutrino problem as reported by Super-Kamiokande.

title: ANOMALY FOR MODEL BUILDING
abstract: A simple algorithm to calculate the group theory factor entering in anomalies at four and six dimensions for SU(N) and SO(N) groups in terms of the Casimir invariants of their subgroups is presented. Explicit examples of some of the lower dimensional representations of SU(n), n ≤ 5 and SO(10) groups are presented, which could be used for model building in four and six dimensions.

title: Magnetic moments and the structure function of the proton
abstract: The EMC collaboration have reported a measurement of the proton structure function which has been interpreted to mean that the spin of the proton is not predominantly that of the quarks (ΔΣ=Δμ+Δd+Δs=0.13±0.19). We show that the magnetic moments of the baryons are independent of this measurement and are given (within 10-20%) for a range of ΔΣ including the valence model value ΔΣ=1. The magnetic moments of the quarks can only be fixed if the quantity ΔΣ is determined very accurately.

title: Soft photons from relativistic heavy ion collisions.
abstract: Production of soft photons in relativistic heavy ion collisions due to bremsstrahlung processes in quark matter and hadronic matter is studied. The contribution of pion-driven processes is found to dominate the yield.